A Systemic Approach to Chest Radiographic Assessment in Mycobacterium tuberculosis-Infected Cynomolgus Macaques (Macaca fascicularis)
This study aimed to establish a comprehensive and accurate numerical chest X-ray radiograph (CXR) scoring system in cynomolgus macaques by using image intensity values from healthy, tuberculosis (TB)-free animals as references. The CXRs were obtained in both dorsoventral and lateral postures from 90 macaques and viewed by the RadiAnt DICOM Viewer software version 2023.1. The mean and maximum intensity values were analyzed and showed significant differences between sex (male and female) and age class (juvenile and subadult/adult), varying based on body sizes. The cutoff values were, therefore, set separately and were tested for accuracy in detecting TB status in 18 naturally Mycobacterium tuberculosis-infected macaques, which were assessed for active tuberculosis infection (ATBI) using Xpert MTB/RIF Ultra at least once during a 12-month follow-up. Only the cutoff values of maximum lateral image intensity (MLIs) correctly identified TB infection in 100% of cases. Thus, the MLIs were selected to follow up on the development of TB lesions in those 18 Mycobacterium tuberculosis-infected macaques. The lateral digital radiograph was divided further into 9 areas, and the MLIs can predict the progression of TB lesions, which were most likely located in the dorsal part of the cranial lung lobe between thoracic vertebrae 1 (T1) to T4. Finally, the CXR results of another group of 8 Mycobacterium tuberculosis-exposed macaques, whose TB status was either uninfected, latent, or ATBI, were compared between a blind test by an expert radiologist and our established CXR scoring system. The blind test results showed 62.5% (5/8) agreement with our scoring system. This suggests that the CXR-MLI scoring system can be used as a supplementary tool for TB diagnosis in cynomolgus macaques.
Introduction
Tuberculosis (TB) remains the world’s leading cause of death from an infectious agent. The primary agent of TB is Mycobacterium tuberculosis, which infects over 10 million people annually, with more than 6.9 million cases of pulmonary TB reported in 2023. The mortality rate for untreated TB can reach approximately 50%, underscoring its persistent status as a global health crisis.1 Since the M. tuberculosis discovery by Robert Koch on March 24, 1882, research into diagnosis, treatment, and prevention has continued to evolve.2
Cynomolgus macaques (Macaca fascicularis), an Old-World monkey species, are increasingly used as a laboratory model for TB research due to their physiologic and immunologic similarities to humans. They provide critical insights into disease mechanisms, particularly concerning upper airway infections, disease transmission, progression, and lower airway lung disease. Their immune response to M. tuberculosis is closely aligned with that of humans, making them ideal for preclinical testing of drugs and vaccines.3,4
TB is an airborne, chronic infectious disease with zoonotic potential that affects both humans and nonhuman primates (NHPs). Effective and early detection of TB is vital for minimizing health risks associated with exposure in both animals and their caretakers.5,6 Diagnosing TB in cynomolgus macaques employs various methods similar to those used in humans, including the intradermal tuberculin skin test (TST), interferon-γ release assays (IGRA), sputum culture, molecular testing (conventional PCR, quantitative PCR, and GeneXpert MTB/RIF [hereafter “Xpert”]), and chest X-rays (CXRs). Each diagnostic method has its advantages and limitations, necessitating a synergistic approach for optimal detection.
CXR is a routine, noninvasive technique widely used in NHP facilities for colony management and research. While baseline CXR parameters have been developed for several NHP species, a systematic scoring system for assessing the severity of respiratory diseases or lesions has not been established.7–10 In humans, CXR is the standard imaging method for TB diagnosis, employing a scoring system that estimates disease severity by dividing the radiograph into 6 zones. However, this method is subjective and unsuitable for interpreting NHP radiographs, due to anatomic differences: specifically, that monkeys are quadrupedal, which affects where granulomas may appear.11,12
CXR interpretation can be hindered by common errors and limitations, such as difficulties in assessing soft tissue contrast and missed lung cancer diagnoses.13 In addition, the shortage of skilled thoracic radiologists can further complicate accurate interpretations.14 In NHPs, pulmonary TB is particularly challenging to detect via CXR, as nodular calcifications are infrequently visible, tubercles may undergo significant caseation necrosis, and extrapulmonary infective sites might not show on radiographs.15 Thus, this study aims to create a comprehensive CXR scoring system for cynomolgus macaques, using image intensity values from healthy, uninfected animals as reference values and testing the effectiveness of the scoring system for detecting TB exposure in naturally M. tuberculosis-infected macaques.
Materials and Methods
Ethical statement for laboratory animal care and use.
The experiment protocol in healthy, TB-free cynomolgus macaques was approved by the IACUC of the National Primate Research Center of Thailand-Chulalongkorn University (NPRCT-CU). The experiment in naturally M. tuberculosis-infected cynomolgus macaques kept at Krabok-Koo Wildlife Breeding Center (KBK), Chachoengsao Province, Eastern Thailand, which is under the authority of the Department of National Parks, Wildlife and Plant Conservation of Thailand (DNP), was approved by the DNP. The experimental procedures in captive macaques at the KBK were approved by the IACUC of Mahidol University and the National Science and Technology Development Agency. The experiments strictly adhered to the principles stated in the Guide for the Care and Use of Laboratory Animals.
Experimental animals, housing, and husbandry.
Healthy and TB-free macaque subjects.
Ninety healthy, TB-free cynomolgus macaques housed at NPRCT-CU, which is an AAALAC-accredited program, were subjected to this study. They were divided into 3 age classes (15 males and 15 females in each age class): juvenile (less than 3 years), subadult (3 to 6 years), and adult (greater than 6 years). The CXRs were obtained during the semiannual health check in January 2023. Their body weight ranges from 1.3 to 1.8 kg (see Table 1). The animals were housed in an indoor, semi-open, social, stainless steel gang cage (approximately 4.0 × 4.0 × 3.0 to 3.5 m, W × L × H) with a polyurethane-coated floor at a temperature of 21 to 29 °C, with relative humidity of 50% to 70%. The light cycle followed the outside environment with the artificial fluorescence light on at 6 am and off at 6 pm. The cage was cleaned and washed twice a day. The animals were fed a standard monkey diet (Perfect Companion Group, Bangkok, Thailand) in the morning (9:00 to 10:00 am), with supplementation of fresh fruits in the afternoon (2:30 to 3:30 pm). The animals were given hyperchlorinated water at pH 7.3 to 7.7, available ad libitum.
| Age class | Body weight range (kg) | Dorsoventral thoracic intensity values | Lateral thoracic intensity values | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Mean | Maximum | Mean | Maximum | |||||||
| Male | Female | Male | Female | Male | Female | Male | Female | Male | Female | |
| Juvenile | 1.3–3.3 | 1.3–2.8 | 42.3 ± 3.7 a | 39.4 ± 2.8 a , * | 164.4 ± 23.7 a | 166.2 ± 15.2 a | 31.2 ± 6.6 a | 32.3 ± 6.5 a , * | 146.9 ± 19.7 a | 133.5 ± 12.8 a |
| Subadult | 2.8–8.4 | 2.4–5.2 | 36.4 ± 4.4 | 36.0 ± 4.8* | 149.1 ± 13.1 | 156.1 ± 13.7 | 29.0 ± 7.0 | 24.9 ± 6.8* | 124.1 ± 8.5 | 119.1 ± 13.4 |
| Adult | 4.8–10.8 | 3.1–10.5 | 38.6 ± 8.7 | 33.6 ± 4.5* | 147.0 ± 21.7 | 155.4 ± 7.7 | 28.7 ± 6.9 | 20.9 ± 5.4* | 117.1 ± 13.6 | 116.3 ± 14.3 |
Mean and maximum values statistically differ between juveniles and other age classes.
Mean values differ between males and females.
Animals were anesthetized by an intramuscular injection of 3 to 5 mg/kg body weight of Zoletil 100 (Virbac, Fort Worth, TX) mixed with 0.03 to 0.05 mg/kg body weight of dexmedetomidine hydrochloride (Zoetis, Parsippany, NJ). After being anesthetized, monkeys were physically examined, and evaluation for detection of TB was performed following the protocol of the NPRCT-CU, including CXR, TST, mIGRA, and IS6110-nested PCR. TST was performed on the eyelid. Animals were intradermally injected with 0.1 mL of Mammalian Old Tuberculin solution (Tuberculin; Zoetis) into one eyelid near the margin. TST reactions were assessed at 24, 48, and 72 h postinjection, and swelling and reddening were scored at 0 to 5 following the established protocols.16 The results were interpreted as negative (for scoring levels 0 to 2) and positive (for scoring levels 3 to 5). The blood sample was collected for mIGRA17, and the pharyngeal wash was collected for IS6110-nested PCR.18 After all procedures were completed, animals were intramuscularly injected with atipamezole hydrochloride (Zoetis) at the same dose as dexmedetomidine hydrochloride and returned to their home cages. Animals were observed until they were fully recovered.
M. tuberculosis-infected macaque subjects.
Eighteen subadult/adult cynomolgus macaques (13 males and 5 females), which were exposed to M. tuberculosis by being housed at KBK in the same gang cage (4 × 10 × 4 m, W × L × H) or in the vicinity of the M. tuberculosis-infected macaques reported previously,17 were recruited for this study. They were followed for 12 months (from December 2021 to November 2022) and confirmed, at least once during the 12-month period, to have active M. tuberculosis infection (ATBI) by Xpert.19 Their body weights ranged from 2.5 to 9.0 kg. The housing environment was an outdoor colony exposed to natural environmental conditions. The monkeys were fed cooked rice in the morning (9:00 to 10:00 am) and fresh fruits and vegetables such as melon, banana, guava, dragon fruit, and cucumber in the afternoon (2:00 to 3:00 pm), with drinking water provided ad libitum. The monkeys were anesthetized, and the physical examination and CXR were done as for the healthy NPRCT-CU monkeys mentioned above. Pharyngeal wash was collected for Xpert. The CXR radiograph intensities were analyzed using our established scoring systems mentioned below, and the results were compared with those of Xpert. Animals were followed up for one year at 0, 3, 6, and 12 months. Some animals naturally died during the 12-month follow-up, resulting in a reduction in numbers to 18, 16, 14, and 13, respectively, at each interval.
M. tuberculosis-exposed macaque subjects.
Eight adult cynomolgus macaques (7 males and 1 female), body weights 3.8 to 11.2 kg, that were housed at KBK and exposed to M. tuberculosis-infected macaques reported previously,17 but whose TB status was either active, latent, or uninfected, were recruited for this study. They were anesthetized, and biologic specimens for mIGRA and IS6110-nested PCR were collected, and TST and CXR were performed. The CXR radiographs were reviewed by a radiologist certified by the American College of Veterinary Radiology (Dr. Rachel E. Pollard) to evaluate the lung condition (blind test). The scoring level was 0 to 3, and the results were interpreted as abnormal at scoring levels 1 to 3. The CXR interpretations were then compared with the radiograph intensities analyzed using our established CXR scoring system.
Chest radiographs and chest radiographic measurements.
After being anesthetized, the monkeys were positioned on a wireless flat panel detector beneath the portable X-ray system. Images were captured during the inspiratory phase of respiration by 2 assistants wearing appropriate shielding to prevent radiation exposure. Dorsoventral and right lateral thoracic radiographs were obtained from all monkeys.
The radiography device used was a portable X-ray system for veterinary use (Model PXP-20HF plus; POSKOM) with a wireless flat panel detector for digital radiography (Model VIVIX-S 1417W; Vieworks, Anyang, Republic of Korea). The digital detector was exposed to X-rays at 70 to 90 KVp with an approximate detector-to-tube distance of 70 cm. Exposure times were no greater than 0.1 to 0.2 s, resulting in 1.0 to 2.0 mAs of exposure.
The digital radiograph images from 90 healthy, uninfected NPRCT-CU cynomolgus macaques and 18 M. tuberculosis-infected KBK cynomolgus macaques were exported to DICOM image files for interpretation and measurement by a licensed veterinarian. Since monkeys and dogs share similarities in quadrupedal movement, the segmentation system used for CXR images of aspiration pneumonia in dogs was modified and applied to thoracic radiographs in monkeys, in which the radiograph was divided into 9 areas for radiographic measurement.20 The radiographic measurement process was divided into 2 steps: image preparation and image measurement.
Image preparation.
The RadiAnt DICOM Viewer software version 2023.1 (Medixant, Poznan, Poland) was used, which allowed us to view the digital radiographs on the computer and use built-in tools for measurements. The image preparation began by adjusting the brightness (window-level value) of the dorsoventral and lateral thoracic radiographs to 9500 and the contrast (window-width value) to 5500. The image was then saved with these settings to measure the intensity. The measurement was performed only in the entire lung for the dorsoventral radiograph (Figure 1), while it was done either in the entire lung (Figure 2A) or after the lung was divided into 9 areas for the lateral radiograph (Figure 2B).
Citation: Journal of the American Association for Laboratory Animal Science 2025; 10.30802/AALAS-JAALAS-25-056
Citation: Journal of the American Association for Laboratory Animal Science 2025; 10.30802/AALAS-JAALAS-25-056
The lateral thoracic radiograph was divided into 9 areas by 2 horizontal (H1 and H2) and 2 vertical (V1 and V2) lines (Figure 2B). The first horizontal line (H1) extended from the center of the manubrium sterni to the costodiaphragmatic recess. The second horizontal line (H2) ran from the caudal edge of the second corpus sterni to the upper intersection between the caudal vena cava and the diaphragm. The first vertical line (V1) extended from the caudal edge of the fourth corpus sterni to the caudal edge of the fourth thoracic vertebrae. The second vertical line (V2) extended from the end of the xiphoid process to the caudal edge of the eighth thoracic vertebrae. Following this setting, the image intensity of the 9 areas was measured.
Image measurement.
For the dorsoventral radiograph, the intensity of the entire lung was analyzed using ImageJ software version 1.54d. The process began by dividing the lung area into 2 (left and right) sides using the spinal bone as a reference (Figure 1). A line was drawn in ImageJ from the point between the first and second thoracic vertebrae straight down, parallel to the spinal bone, until it reached the diaphragmatic surface. Next, a line was traced along the diaphragmatic surface to the end of the costodiaphragmatic recess, followed by a final line along the inner border of the chest wall, connecting back to the starting point.
For the lateral thoracic radiograph, the image intensity of the entire lung (Figure 2A) and the lung divided into 9 areas (with 4 H and V lines) (Figure 2B) was also done using ImageJ software version 1.54d. For the total area image intensity measurement, the process began by drawing a line in ImageJ from the center of the manubrium sterni to the cranio-ventral edge of the first thoracic vertebra. A line was then drawn from the bottom edge of the vertebra down to the costodiaphragmatic recess. Next, a line was drawn along the diaphragmatic surface to the end of the xiphoid process, followed by an inner border of the sternum, connecting back to the starting point (Figure 2C).
For the 9-area image intensity measurement of the lateral thoracic radiograph, the outer line was defined by the line drawing used for the total area image intensity and the 2 horizontal (H1 and H2) and 2 vertical (V1 and V2) lines, which were placed above the outer line. The image intensity of each of the 9 areas was measured by drawing a line covering each area. When the line reached the border of an H or V line, it followed the H or V line without overlapping until it returned to the starting point. This process was repeated until all 9 areas were fully measured (Figure 2D). The maximum, mean, and minimum image intensities of the dorsoventral and lateral radiographs were acquired and analyzed.
Statistical methods.
All intensity data for the total area and 9 specific areas from 90 healthy NPRCT-CU cynomolgus macaques were presented as mean ± SD. Data processing, management, and statistical analysis were conducted using GraphPad Prism version 10.4.1 software (GraphPad, Boston, MA). Initially, an unpaired t test was used to examine the effect of sex, followed by a one-way ANOVA to assess the effects of age and age × sex interactions. The Tukey multiple comparisons test was then used to identify differences between 3 age classes and between sexes. The cutoff values of healthy NPRCT-CU macaques were calculated. Later, the intensity data of radiographic images for the total areas and 9 specific areas from 18 M. tuberculosis-infected KBK macaques were analyzed and compared with the cutoff values of the NPRCT-CU macaques. For the 8 M. tuberculosis-exposed monkeys, the correlation of the CXR results between those provided by the expert radiologist and those identified using our established CXR scoring system was analyzed using Pearson correlation analysis and χ2 test. The significant differences for all analyses were set at P < .05.
Results
Thoracic radiograph image intensity values of healthy cynomolgus macaques.
All 90 healthy, uninfected NPRCT-CU cynomolgus macaques showed normal clinical signs based on the veterinary physical examination and negative results for all TB diagnostic tests, including TST, mIGRA, and IS6110-nested PCR (data not shown). The dorsoventral and lateral thoracic radiograph image intensities from 90 healthy cynomolgus macaques are presented in Table 1. Note that the minimum intensity values for both dorsoventral and lateral thoracic radiograph images are zero for all individuals and are not included in Table 1.
Dorsoventral radiograph.
Mean and maximum values in juvenile monkeys, for both males and females, were significantly higher than those for the subadult and adult monkeys, though there was no significant difference between subadults and adults. Statistically significant differences between sexes were detected for mean values in each age class (P < .05) but not for maximum values. Thus, the nonsignificantly different results were combined between age classes (between subadults and adults, for mean and maximum values) and between sexes (for maximum values). The cutoff values for the dorsoventral radiographs were calculated as mean + 1SD, as shown in Table 2. For example, the total area maximum intensity value for juvenile monkeys is 165.2 ± 19.9; the cutoff value becomes 185.1. The values higher than the cutoff value were evaluated as positive CXR findings.
| Age class | Dorsoventral thoracic intensity values | Lateral thoracic intensity values | ||||
|---|---|---|---|---|---|---|
| Mean | Maximum | Mean | Maximum | |||
| Male | Female | Male-Female | Male | Female | Male-Female | |
| Juvenile | 46.0 | 42.2 | 185.1 | 37.8 | 38.8 | 157.9 |
| Subadult/adult | 44.3 | 39.6 | 167.0 | 35.7 | 29.3 | 131.9 |
The values were modified from Table 1 by combining the nonsignificant values between age classes and between sexes, and the cutoff values were calculated as mean + 1SD.
Lateral radiograph.
Mean and maximum values of the entire lung, for both males and females, in juvenile monkeys were significantly higher than those in subadult and adult monkeys, while there was no difference between subadults and adults. Mean and maximum intensity values for males in each age class tended to be higher than those for females. However, the statistically significant differences between sexes were detected only in mean values (P < .05), not in maximum values. Thus, the nonsignificantly different results were combined between age classes (between subadults and adults, for mean and maximum values) and between sexes (for maximum values). The cutoff values for the lateral radiographs were calculated as mean + 1SD, as shown in Table 2. For example, the total area maximum intensity value for juvenile monkeys is 140.2 ± 17.7; the cutoff value becomes 157.9. The values higher than the cutoff value were evaluated as positive CXR findings.
The thoracic radiograph image intensities of 9 areas were then calculated (Table 3). The mean and maximum values for juveniles were significantly higher than those of subadults and adults, except for area 9 for mean values and areas 4, 6, and 9 for maximum values. No significant differences in the mean and maximum values were detected between subadults and adults, except for areas 4 and 8 for maximum values. The statistically significant differences between sexes in mean values were detected in all areas, except areas 6, 8, and 9, and maximum values were detected in area 3 only. The lowest maximum intensity value was 29.5 ± 16.7 in area 9 of subadult female monkeys, and the highest was 119.9 ± 15.2 in area 1 of juvenile female monkeys. The lowest and highest mean intensity values were also in the same areas as the maximum intensity values. The lowest mean intensity value was 2.5 ± 2.7 in adult female monkeys, and the highest was 56.6 ± 8.2 in juvenile male monkeys.
| Area 1 | Area 2 | Area 3 | ||||
|---|---|---|---|---|---|---|
| Age/sex | Mean | Maximum | Mean | Maximum | Mean | Maximum |
| Juvenile | ||||||
| Male | 56.6 ± 8.2a, * | 119.0 ± 18.5a | 36.7 ± 9.2a, * | 91.1 ± 13.0a | 17.3 ± 5.1a, * | 72.5 ± 12.2a, * |
| Female | 53.9 ± 8.3a | 119.9 ± 15.2a | 33.2 ± 6.0a | 94.3 ± 12.9a | 13.9 ± 4.0a | 58.9 ± 14.1a |
| Subadult | ||||||
| Male | 54.0 ± 9.5 * | 111.6 ± 12.4 | 29.9 ± 6.9 * | 81.1 ± 8.6 | 11.7 ± 5.9 * | 57.3 ± 12.3 * |
| Female | 46.2 ± 8.0 | 111.7 ± 13.2 | 25.0 ± 8.4 | 78.6 ± 9.5 | 10.0 ± 5.0 | 54.0 ± 13.1 |
| Adult | ||||||
| Male | 55.0 ± 10.5 * | 109.3 ± 16.0 | 29.8 ± 12.0 * | 80.5 ± 8.8 | 12.8 ± 9.0 * | 54.1 ± 12.0 * |
| Female | 42.6 ± 8.0 | 107.9 ± 11.3 | 24.1 ± 8.5 | 74.3 ± 9.4 | 8.5 ± 5.2 | 51.3 ± 16.2 |
| Area 4 | Area 5 | Area 6 | ||||
| Age/sex | Mean | Maximum | Mean | Maximum | Mean | Maximum |
| Juvenile | ||||||
| Male | 43.3 ± 7.4a, * | 91.5 ± 12.5 | 45.5 ± 7.2a, * | 97.3 ± 15.5a | 10.7 ± 3.4a | 70.8 ± 12.5 |
| Female | 46.2 ± 9.5a | 90.7 ± 8.9 | 46.2 ± 6.9a | 97.0 ± 6.9a | 9.0 ± 2.8a | 62.9 ± 13.2 |
| Subadult | ||||||
| Male | 37.5 ± 7.0 * | 86.3 ± 8.5b | 39.7 ± 6.7 * | 81.3 ± 6.3 | 6.6 ± 2.7 | 61.0 ± 8.1 |
| Female | 29.1 ± 8.6 | 81.8 ± 9.5b | 34.5 ± 7.1 | 84.8 ± 7.8 | 5.6 ± 2.6 | 62.5 ± 12.1 |
| Adult | ||||||
| Male | 42.0 ± 10.8 * | 103.2 ± 13.6 | 39.3 ± 8.4 * | 91.6 ± 22.3 | 6.6 ± 3.9 | 59.7 ± 10.3 |
| Female | 23.8 ± 7.1 | 91.7 ± 18.5 | 30.5 ± 7.9 | 81.8 ± 9.6 | 5.3 ± 2.7 | 64.9 ± 17.0 |
| Area 7 | Area 8 | Area 9 | ||||
| Age/sex | Mean | Maximum | Mean | Maximum | Mean | Maximum |
| Juvenile | ||||||
| Male | 41.6 ± 13.9a, * | 74.7 ± 18.6a | 36.8 ± 7.2a | 92.2 ± 13.4 | 5.7 ± 7.2 | 33.2 ± 14.7 |
| Female | 49.1 ± 14.9a | 82.3 ± 15.4a | 43.8 ± 10.0a | 90.1 ± 12.0 | 5.4 ± 4.9 | 35.8 ± 17.2 |
| Subadult | ||||||
| Male | 31.0 ± 13.4 * | 67.5 ± 15.8 | 29.1 ± 6.4 | 79.0 ± 10.4b | 4.9 ± 6.3 | 32.6 ± 17.9 |
| Female | 23.2 ± 12.4 | 67.4 ± 13.3 | 26.2 ± 7.2 | 83.5 ± 17.6b | 3.1 ± 3.9 | 29.5 ± 16.7 |
| Adult | ||||||
| Male | 33.6 ± 15.6 * | 73.3 ± 17.2 | 34.5 ± 10.5 | 89.7 ± 15.6 | 4.1 ± 3.4 | 35.3 ± 23.3 |
| Female | 9.8 ± 6.6 | 54.9 ± 21.3 | 25.8 ± 6.9 | 90.8 ± 16.8 | 2.5 ± 2.7 | 34.7 ± 15.0 |
Gray shadings indicate the lowest and the highest values. Bold indicates significant values.
a,bMean and maximum values significantly differ between juvenile and subadult/adult, and between subadult and adult in each area.
Mean and maximum values significantly differ between males and females in each area.
To test if the mean values were correlated with the maximum values for dorsoventral and lateral radiographs, a Pearson correlation analysis between these 2 values was calculated in total areas (dorsoventral: P = .012, r = 0.264; lateral: P < .001, r = 0.81) and in 9 areas (lateral only: P < .001, r = 0.383 [area 4] to 0.713 [area 7]). This indicated that the maximum values were correlated with the mean values; thus, only the cutoff values of the maximum intensity were used in the next steps of the 9 areas analysis (Table 4).
| Age/sex | Cutoff maximum image intensity values of 9 areas | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Area 1 | Area 2 | Area 3 | Area 4 | Area 5 | Area 6 | Area 7 | Area 8 | Area 9 | |
| Juvenile | |||||||||
| Male | 137.5 | 104.1 | 84.7 | 104.0 | 112.8 | 83.3 | 93.2 | 105.6 | 47.9 |
| Female | 135.2 | 107.1 | 72.9 | 99.6 | 103.9 | 76.2 | 97.7 | 102.2 | 53.0 |
| Subadult-Adult | |||||||||
| Male | 124.5 | 89.4 | 67.7 | 108.8 | 103.4 | 69.4 | 86.9 | 98.5 | 54.4 |
| Female | 122.0 | 86.0 | 67.2 | 102.1 | 92.0 | 78.2 | 79.7 | 104.4 | 47.9 |
Thoracic radiograph image intensity measurements in M. tuberculosis-infected macaques.
Eighteen monkeys kept at KBK tested positive for M. tuberculosis by Xpert at least once during a 12- month follow-up, resulting in a total of 21 positive results. However, one Xpert positive was detected in the KBK055 monkey (at month 3), while the CXR was not performed. Thus, only 20 Xpert-positive results were used to compare with the CXR results. Based on the cutoff mean and maximum values identified in healthy animals (see Tables 2 and 3), the positive and negative CXR results of 18 M. tuberculosis-infected monkeys can be described as follows.
Dorsoventral radiograph.
The mean and maximum intensity values of the total areas ranged from 17.3 (KBK055, month 0) to 109 (KBK049, month 12) and from 141.5 (KBK120, month 0) to 254 (KBK103, month 3), respectively (Table 5). Using the cutoff mean and maximum dorsoventral image intensity values defined in Table 2, the CXR-positive results identified by the dorsoventral image mean and maximum intensity cutoff values were 40% (8/20) and 40% (8/20) agreement with those of the Xpert-positive results (Table 5).
| No. | Monkey ID | Sex | Age class | Month 0 | Month 3 | Month 6 | Month 12 | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean | Maximum | Mean | Maximum | Mean | Maximum | Mean | Maximum | ||||
| 1 | KBK046 | M | Adult | 19.6 | 152.5 | 32.9 | 180.0 | — | — | — | — |
| 2 | KBK049 | M | Adult | 45.4 | 144.0 | 59.5 | 167.5 | 94.1 | 188.5 | 109.0 | 215.5 |
| 3 | KBK055 | M | Adult | 17.3 | 151.0 | ND | ND | 40.6 | 211.0 | 24.3 | 187.0 |
| 4 | KBK091 | F | Adult | 46.6 | 150.0 | — | — | — | — | — | — |
| 5 | KBK096 | M | Adult | 39.2 | 161.0 | 59.0 | 186.0 | ND | ND | 44.7 | 179.0 |
| 6 | KBK099 | F | Subadult | 22.9 | 145.5 | 46.1 | 229.5 | 49.0 | 165.5 | — | — |
| 7 | KBK100 | M | Adult | 36.3 | 152.0 | 70.1 | 238.0 | 88.7 | 199.0 | 75.2 | 186.0 |
| 8 | KBK102 | F | Adult | 26.8 | 164.0 | 57.1 | 248.5 | 55.4 | 200.0 | 53.3 | 200.5 |
| 9 | KBK103 | M | Adult | 29.6 | 158.0 | 71.4 | 254.0 | — | — | — | — |
| 10 | KBK105 | M | Adult | 26.1 | 146.0 | 68.8 | 217.0 | 50.7 | 183.0 | 52.7 | 212.5 |
| 11 | KBK120 | M | Adult | 19.7 | 141.5 | 83.3 | 240.0 | 62.6 | 188.5 | 59.7 | 195.5 |
| 12 | KBK195 | M | Adult | 27.7 | 159.5 | 40.9 | 230.0 | 62.8 | 184.0 | 45.4 | 187.5 |
| 13 | KBK199 | M | Adult | 29.4 | 154.5 | 97.9 | 249.0 | 75.3 | 186.5 | 52.0 | 202.0 |
| 14 | KBK264 | M | Adult | 35.9 | 158.0 | 41.0 | 245.0 | 43.6 | 194.0 | 52.3 | 211.5 |
| 15 | KBK266 | M | Adult | 44.2 | 175.0 | 51.1 | 237.5 | 56.7 | 187.0 | 29.8 | 211.5 |
| 16 | KBK292 | F | Subadult | 27.8 | 159.0 | 41.6 | 198.0 | 26.4 | 170.5 | 48.6 | 184.5 |
| 17 | KBK293 | F | Subadult | 21.5 | 144.5 | 45.8 | 178.5 | 35.9 | 184.5 | — | — |
| 18 | KBK298 | M | Adult | 48.4 | 161.0 | 66.3 | 238.5 | 57.2 | 188.0 | 40.4 | 193.0 |
Abbreviation: ND, no CXR data.
Positive and negative CXR results were evaluated based on the cutoff values of mean (44.3 for males [M] and 39.6 for females [F]) and maximum (167.0 for both sexes) image intensity defined in Table 2. Twenty-one positive results provided by Xpert MTB/RIF Ultra testing are highlighted in light gray, and dark gray indicates the positive results determined by Xpert and CXR. Bold indicates positive CXR values. — indicates the time when the animal died.
Lateral radiograph.
As shown in Table 6, the mean and maximum intensity values of total areas ranged from 4.2 (KBK055, month 0) to 67.5 (KBK049, month 3) and from 119 (KBK049, month 0) to 238 (KBK100, month 12), respectively. Noted, the highest mean value in the KBK049 monkey and the highest maximum value in the KBK100 monkeys synchronized with the Xpert-positive results.
| Image intensity value | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Monkey ID | Sex | Age class | Month 0 | Month 3 | Month 6 | Month 12 | ||||
| Mean | Maximum | Mean | Maximum | Mean | Maximum | Mean | Maximum | |||
| KBK046 | M | Adult | 6.9 | 153 | 28.8 | 204 | — | — | — | — |
| KBK049 | M | Adult | 4.9 | 119 | 67.5 | 187 | 59.3 | 204 | 39.2 | 221 |
| KBK055 | M | Adult | 4.2 | 153 | ND | ND | 6.1 | 119 | 5.2 | 136 |
| KBK091 | F | Adult | 37.7 | 136 | — | — | — | — | — | — |
| KBK096 | M | Adult | 27.2 | 170 | 31.0 | 170 | ND | ND | 21.3 | 173 |
| KBK099 | F | Subadult | 12.8 | 170 | 26.4 | 156 | 24.9 | 153 | — | — |
| KBK100 | M | Adult | 19.9 | 170 | 37.6 | 213 | 31.5 | 221 | 64.2 | 238 |
| KBK102 | F | Adult | 15.0 | 136 | 50.2 | 189 | 29.5 | 173 | 41.2 | 214 |
| KBK103 | M | Adult | 18.4 | 153 | 56.2 | 206 | — | — | — | — |
| KBK105 | M | Adult | 12.5 | 153 | 27.4 | 173 | 37.0 | 187 | 25.4 | 187 |
| KBK120 | M | Adult | 8.2 | 169 | 29.7 | 172 | 27.0 | 173 | 23.5 | 156 |
| KBK195 | M | Adult | 10.7 | 153 | 35.2 | 156 | 44.3 | 204 | 20.8 | 187 |
| KBK199 | M | Adult | 17.0 | 187 | 64.6 | 222 | 33.9 | 170 | 36.4 | 222 |
| KBK264 | M | Adult | 11.9 | 170 | 24.4 | 222 | 24.3 | 181 | 23.0 | 187 |
| KBK266 | M | Adult | 12.7 | 187 | 18.8 | 206 | 47.0 | 206 | 25.3 | 158 |
| KBK292 | F | Subadult | 5.6 | 119 | 18.5 | 187 | 8.8 | 153 | 27.5 | 170 |
| KBK293 | F | Subadult | 7.4 | 153 | 20.9 | 170 | 11.3 | 136 | — | — |
| KBK298 | M | Adult | 22.1 | 170 | 45.9 | 222 | 36.5 | 187 | 28.4 | 187 |
Positive and negative CXR results were evaluated based on the cutoff of mean (35.7 for males and 29.3 for females) and maximum (131.9 for both sexes) image intensity values defined in Table 2. Twenty-one positive results provided by Xpert MTB/RIF Ultra testing are highlighted in light gray, and dark gray indicates the positive results determined by Xpert and CXR. Bold indicates positive CXR values. — indicates the time when the animal died.
Using cutoff mean and maximum intensity values defined in Table 2, the CXR-positive results identified by the lateral image mean cutoff value were only 20% (4/20) aligned with those of the Xpert-positive results, while the use of the maximum cutoff value showed 100% (20/20) agreement.
Because of the 100% agreement between the Xpert-positive results and the lateral radiograph-positive results identified by maximum intensity cutoff value, only the maximum intensity cutoff value of the lateral radiograph was selected for the next step of the study.
Use of maximum lateral radiograph intensity value to follow up the development of TB lesions in M. tuberculosis-infected monkeys.
To follow up on the development of the TB lesions in 18 M. tuberculosis-infected KBK monkeys, the maximum lateral radiograph intensity value (MLI), at the time that the Xpert first presented the positive result, in each monkey, was designated as month 0, and values before and after this point were placed in the negative and positive direction in the x-axis of the graph (see Figure 3). Only 6 monkeys had the CXR data oriented in the negative direction. Four (KBK049, KBK055, KBK099, and KBK293), one (KBK292), and one (KBK100) monkeys were detected to be M. tuberculosis Xpert positive for the first time in months 3, 6, and 12, respectively; and their MLIs in 3 or 6 months ahead (or at months 0, 3 and 6) were higher than the maximum cutoff value (131.9), except KBK049 that the MLI at month 0 was 119. Considering the MLIs 3 months after the Xpert showed positive results, it was found that the MLIs of 15 out of 16 monkeys (94%) were higher than the cutoff value; only KBK055 at month 6 had an MLI of 119. Notably, the MLIs of KBK100 remained higher than the cutoff value throughout the 12- month follow-up, even though the M. tuberculosis Xpert positive was presented on month 12. This suggests that MLI values can be used for early detection of positive CXR findings (at least 3 months ahead) and for monitoring of the development of TB lesions in cynomolgus monkeys.
Citation: Journal of the American Association for Laboratory Animal Science 2025; 10.30802/AALAS-JAALAS-25-056
Use of each of the 9 areas of MLI to predict the most likely location of TB lesion.
We further analyzed whether the MLI of each of the 9 areas can predict the most likely location of TB lesion. As there were only 2 out of 9 areas that showed differences in MLIs between subadults and adults, the subadult and adult MLIs from Table 3 were combined, and cutoff values were established for 9 areas (Table 4). We then compared the MLIs across these 9 areas in 17 M. tuberculosis-infected KBK macaques, only when they first tested positive for M. tuberculosis using Xpert, excluding KBK055 because his CXR result was not available at month 3. The highest agreement levels between the MLIs and the Xpert-positive results were observed in areas 1, 4, and 5 with 88.2% (15/17), 41.2% (7/17), and 41.2% (7/17), respectively (Table 7). In contrast, areas 3 and 9 had the lowest agreement levels with 17.7% (3/17). Areas 2, 6, and 8 showed relatively low agreement levels of 29.4% (5/17). These findings suggest that the most likely location of the TB lesion in cynomolgus macaques is area 1.
| Monkey ID | Cutoff value | Area | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | ||
| Male | 124.5 | 89.4 | 67.7 | 108.8 | 103.4 | 69.4 | 86.9 | 98.5 | 54.4 | |
| Female | 122.0 | 86.0 | 67.2 | 102.1 | 92.0 | 78.2 | 79.7 | 104.4 | 47.9 | |
| KBK046 | M | 142 | 40 | 36 | 89 | 63 | 34 | 53 | 73 | 40 |
| KBK049 | M | 180 | 129 | 81 | 156 | 135 | 146 | 127 | 137 | 55 |
| KBK091 | F | 107 | 87 | 44 | 91 | 103 | 79 | 92 | 103 | 69 |
| KBK096 | M | 168 | 78 | 48 | 156 | 92 | 53 | 79 | 94 | 33 |
| KBK099 | F | 189 | 113 | 77 | 150 | 122 | 99 | 142 | 110 | 44 |
| KBK100 | M | 188 | 113 | 101 | 187 | 148 | 125 | 121 | 129 | 59 |
| KBK102 | F | 140 | 47 | 34 | 65 | 100 | 46 | 72 | 120 | 18 |
| KBK103 | M | 125 | 54 | 51 | 91 | 90 | 49 | 15 | 84 | 34 |
| KBK105 | M | 126 | 69 | 19 | 54 | 69 | 39 | 26 | 62 | 16 |
| KBK120 | M | 131 | 36 | 28 | 98 | 48 | 16 | 28 | 71 | 14 |
| KBK195 | M | 162 | 88 | 51 | 99 | 99 | 79 | 43 | 79 | 16 |
| KBK199 | M | 141 | 71 | 16 | 103 | 91 | 46 | 68 | 76 | 3 |
| KBK264 | M | 124 | 75 | 27 | 100 | 72 | 54 | 16 | 67 | 15 |
| KBK266 | M | 125 | 73 | 25 | 110 | 94 | 46 | 73 | 87 | 32 |
| KBK292 | F | 129 | 64 | 10 | 76 | 98 | 33 | 39 | 69 | 12 |
| KBK293 | F | 173 | 96 | 22 | 143 | 119 | 42 | 71 | 79 | 29 |
| KBK298 | M | 142 | 69 | 21 | 134 | 93 | 44 | 46 | 104 | 10 |
| No. of positive | 15 | 5 | 3 | 7 | 7 | 5 | 4 | 5 | 3 | |
| Percent of positive | 88.2 | 29.4 | 17.7 | 41.2 | 41.2 | 29.4 | 23.5 | 29.4 | 17.7 | |
Only the MLIs, when the M. tuberculosis-Xpert MTB/RIF Ultra test was first detected positive, are shown. The MLIs that are higher than the cutoff values are indicated in gray shading.
Comparison of CXR measurements between the established scoring system and the expert radiologist’s interpretation in M. tuberculosis-exposed cynomolgus macaques.
Evaluation of the CXR for 8 M. tuberculosis-exposed cynomolgus macaques (Figure 4) showed that 25% (2/8) monkeys received a score of 3, 25% (2/8) received a score of 1, and 50% (4/8) received a score of 0 (Table 8). As a result, 50% (4/8) of the macaques were classified as having normal CXR, and the remaining 50% (4/8) were classified as abnormal. MLIs measured in all 8 macaques, except for the KBK031 monkey, exceeded the cutoff value of 131.9 (Table 8), resulting in 87.5% (7/8) positive results. TST results were negative for all macaques (100%, 8/8). The mIGRA results showed 37.5% (3/8) of the animals to be positive, 25% (2/8) indeterminate, and 37.5% (3/8) having negative results. IS6110-nested PCR detected positive cases in 25% (2/8) of the macaques, corresponding to the indeterminate mIGRA results. The TB status of animals was classified as uninfected (if results were negative results for all 3 tests), latent (if results were positive results on either TST or mIGRA but negative for IS6110-nested PCR), or active (if results were positive for IS6110-nested PCR), respectively. Notably, 2 monkeys (KBK060 and KBK097) that showed negative results for these 3 methods had positive results based on MLI values. A comparison between the radiologist’s scores and the MLIs for each macaque showed that 62.5% (5/8) of the results, except KBK089, KBK097, and KBK268, were consistent. Pearson correlation analysis revealed a significant positive correlation (P = .01, r = 0.82), and the χ2 test indicated no significant difference between these 2 sets of results (P = .1).
Citation: Journal of the American Association for Laboratory Animal Science 2025; 10.30802/AALAS-JAALAS-25-056
| Monkey ID | Sex | Age class | CXR evaluation* | MLIs | TST | mIGRA | IS6110-nested PCR | TB status** | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Score* | Result | Values | Result | |||||||
| KBK008 | M | Adult | 1 | Abnormal | 171 | Positive | Negative | Positive | Negative | Latent |
| KBK031 | M | Adult | 0 | Normal | 129 | Negative | Negative | Negative | Negative | Uninfected |
| KBK060 | M | Adult | 1 | Abnormal | 157 | Positive | Negative | Negative | Negative | Uninfected |
| KBK089 | F | Adult | 0 | Normal | 158 | Positive | Negative | Positive | Negative | Latent |
| KBK095 | M | Adult | 3 | Abnormal | 255 | Positive | Negative | Indeterminate | Positive | Active |
| KBK097 | M | Adult | 0 | Normal | 149 | Positive | Negative | Negative | Negative | Uninfected |
| KBK268 | M | Adult | 0 | Normal | 174 | Positive | Negative | Positive | Negative | Latent |
| KBK294 | M | Adult | 3 | Abnormal | 193 | Positive | Negative | Indeterminate | Positive | Active |
Positive (bold) and negative MLIs were evaluated based on the cutoff value (131.9) defined in Table 2.
0 = normal lung, 1 = interstitial or bronchial lung pattern, 2 = alveolar pattern, and 3 = nodule or granuloma formation.
TB status was classified based on TST, mIGRA, and IS6110-nested PCR results.
Discussion
M. tuberculosis infection in cynomolgus macaques closely resembles that seen in humans.21,22 After initial M. tuberculosis infection, the outcomes in both humans and NHPs can be divided into several categories. First is the immediate clearance of pathogens from the host’s body by his/her innate immune system. Second, the infected individual develops latent TB infection (LTBI), characterized by a persistent immune response to M. tuberculosis, resulting in an asymptomatic and nontransmissible state. The last category is ATBI, which can occur either as a primary TB infection or as a reactivation of LTBI. About 5% of M. tuberculosis infections in humans lead to primary TB, mainly among infants or immunocompromised individuals whose immune systems are unable to defend against M. tuberculosis. Reactivation of LTBI occurs when a previously contained M. tuberculosis infection becomes active, and this is the most common form of ATBI, accounting for 90% of human cases.23–29 Recently, the terms incipient and subclinical TB have been defined. The incipient TB is the most difficult to describe, while the subclinical TB is the stage between LTBI and ATBI where the patients are sporadically infectious and have no or mild clinical TB symptoms, but the abnormalities can be detected using radiologic or microbiologic assays.25,30
TB infection, particularly ATBI, in cynomolgus macaque, results in granulomatous lesions, primarily in the tracheobronchial lymph nodes, lungs, and other organs such as the spleen, liver, and kidneys, along with all stages of granuloma formation.21,22 Consequently, this species can better tolerate the disease, exhibiting a higher incidence of LTBI and reflecting the full spectrum of TB, including primary TB, LTBI, and reactivation of LTBI as seen in humans. Cynomolgus macaques exhibit a complete range of granuloma types, with classic caseous granulomas predominantly observed in the lungs. In addition, the lungs of NHPs exhibit variability across infection sites, with active necrotic lesions and healing lesions coexisting in different granulomas within the same host.21,22,31–33 During this stage, in humans, the M. tuberculosis bacteria can leak from the granuloma and spread through the respiratory tract, including the oral and nasal cavities, which allows M. tuberculosis to be transmitted to others when the patients speak, sneeze, or cough. In some cases, culture-positive ATBI patients may be asymptomatic, and they can be categorized as subclinical TB.23–29 To control the TB disease in both humans and cynomolgus macaques, it is important to identify the LTBI and predict progression of LTBI to ATBI.
Various diagnostic approaches have been recommended and developed for detection of M. tuberculosis infection in NHPs, including evaluations of cellular and humoral immune responses, antigen detection, and clinical assessments. However, these approaches have some drawbacks. The in vivo TST and the in vitro IGRA are vital for evaluating the host’s cellular immune response, and the World Health Organization recommends using either IGRA or TST to test for LTBI in humans.1 The TST, which involves injecting Mammalian Old Tuberculin intradermally into the eyelid or abdominal skin, is routinely used as the standard TB screening tool in NHPs. However, it has several limitations, including issues with specificity, sensitivity, time efficiency, and reliability, as well as challenges in Mammalian Old Tuberculin production and quality control. The IGRA involves collection of peripheral blood and stimulation of immune cells using 2 specific mycobacterial peptides, the 6-kDa early secretory antigenic target (ESAT6) and the 10-kDa culture filtrate protein (CFP-10), and the release of IFN-γ is measured. Although IGRA for NHPs has been reported,17,34,35 the validity of the method is still an issue. Testing for the humoral immune response, such as ELISA or multiplex immunoassays, sometimes has negative results, because the antibody response typically appears later than the cellular immune response.6 For antigen detection, M. tuberculosis culture is considered the gold standard. However, drawbacks include that it is impractical for routine screening of large populations of captive monkeys, and that it is time consuming and requires technical proficiency. In contrast, PCR-based methods, such as IS6110-nested PCR and Xpert provide more rapid diagnostic results but are limited in their ability to evaluate whether the M. tuberculosis infection is active (viable) or inactive (nonviable).25,30 Alternatively, observation of clinical signs, including fever, fatigue, lack of appetite, weight loss, and, in those animals with pulmonary disease, a persistent cough, hemoptysis, and dyspnea, is a simple and noninvasive approach for evalution. However, these typical clinical signs, especially weight loss, are not diagnostically conclusive for male NHPs, since they may be influenced by the social rank of an animal and, consequently, access to food.36 In contrast, CXR offers a noninvasive diagnostic tool to monitor TB progression that can be readily employed in NHP colony management and for experimental protocols using NHPs.3,37,38 However, the interpretation of CXR still relies on human subjectivity and has no standardized dividing and scoring systems available that can provide numerical data estimates for application of CXR in NHPs.
The study described here not only established typical ranges and cutoff values for total and 9 specific areas of thoracic radiograph image intensity values but also demonstrated the interpretation process by using these values to confirm abnormal (positive) CXR findings in naturally M. tuberculosis-infected cynomolgus macaques that were confirmed positive by Xpert. This numerical scoring system, especially the MLIs, can help in the interpretation of CXR results and will exclude subjective bias. Moreover, our scoring system enabled the prediction of abnormal CXR lesion locations based on MLIs from 9 designated areas. It identified the most likely site of TB lesions as the dorsal part of the cranial lung lobe, between thoracic vertebrae T1 and T4 (Area 1). In addition, it can be used to detect early TB infection lesions and serve as a monitoring method. However, this CXR analysis for M. tuberculosis infection cannot be a stand-alone method because it cannot identify the specific cause of the CXR abnormal findings. Further, the diagnosis of M. tuberculosis-exposed monkeys, that had either active, latent or uninfected TB status, made by the expert radiologist compared to our scoring system, showed that consistency was only 62.5% of cases, though it revealed a significant positive correlation (Pearson correlation analysis, P = .01, r = 0.82) and no significant difference between these 2 sets of the results (the χ2 test, P = .1). Thus, the accuracy of this measurement should be approached with caution, and it should be used as a supplementary tool to other TB diagnostic methods for identification of M. tuberculosis infection. In contrast to humans, pulmonary TB in NHPs rarely showed any nodular calcification, and most commonly the tubercles undergo extensive caseation necrosis, thus detection of granulomas in the lung of NHPs is more challenging than those in humans.15
Generally, routine thoracic study should include erect lateral and dorsoventral views. The relatively greater depth of the costodiaphragmatic recesses in macaques, as compared with those in human beings and dogs, increases the importance of the lateral projection. The caudal extent of the costodiaphragmatic recesses cannot be fully evaluated on the frontal projections due to the superimposition of the cranial abdominal organs.15 The lower accuracy (or low correlation between the Xpert and the CXR) of the dorsoventral radiograph than that of the lateral radiograph in this study was because the CXR image taken at the dorsoventral posture included the microchip implanted under the skin, which was not detected in the lateral posture, and caused the false positive results. In addition, the positioning of the monkeys in the dorsoventral posture to be perpendicular to a wireless flat panel detector is more difficult than the lateral posture. Although the lateral CXR seems to be suitable for TB detection in cynomolgus macaques, some difficulties can be encountered, especially in aged monkeys that have spondylosis, as their spinal bone may become more irregular in shape. The spinal bone development can vary among individuals, thus, drawing a line under the ImageJ program might be terminated at thoracic vertebrae 7 or 8, not thoracic vertebrae 10, in some monkeys, leading to errors in the measurement of radiograph intensity values.
The difference in mean and maximum intensity values of images between juveniles and subadult/adult monkeys might be due to their anatomic and body mass. Previously, one study20 attempted to compare CXR findings in dogs with aspiration pneumonia by dividing lateral CXRs into 9 areas at 3 intercostal spaces (fourth, sixth, and eighth) in the dorsal, middle, and ventral thirds of the thorax. The CXR dividing system used in the dogs also varied based on their body size and breed. Thus, it should be kept in mind that different NHP taxa may have different anatomic features which have implications for radiograph images. Nevertheless, this study successfully created a numerical standardized scoring system in cynomolgus macaques, which should be adjusted and/or modified if it is applied to other macaques or NHP species.
The dorsoventral thoracic radiographic images of a healthy, uninfected cynomolgus macaque housed at NPRCT-CU. The window-level value was adjusted to 9500, and the window-width value was adjusted to 5500. The line drawing (yellow) for the total area image intensity measurement. Lt, left; Rt, right.
The lateral thoracic radiographic images of a healthy, uninfected cynomolgus macaque housed at NPRCT-CU. (A) The window-level value was adjusted to 9500, and the window-width value was adjusted to 5500. (B) A radiograph image was divided into 9 areas by 2 horizontal (H1 and H2) and 2 vertical (V1 and V2) lines. (C) Line drawing (yellow) for the total area image intensity measurement. (D) Line drawing (yellow) for the nine-area image intensity measurement.
Maximum intensity values for 18 M. tuberculosis-infected monkeys at 0, 3, 6, and 12 months. The positive result from Xpert M tuberculosis/RIF Ultra testing is designated as month 0, with other maximum intensity values arranged into months −12, −6, −3, +3, +6, and +12. The cutoff value for subadult/adult maximum intensity was set at 131.9.
Chest X-ray radiographs of 8 M. tuberculosis-exposed cynomolgus macaques. Their TB status was either active, latent, or uninfected, based on eyelid-TST, mIGRA, and IS6110-nested PCR detections.
Contributor Notes