Diagnostic efficacy of contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging in idiopathic cerebrospinal fluid rhinorrhea.

We report a case of a 50-year-old woman in which contrast-enhanced fluid-attenuated inversion recovery (FLAIR) was used for the diagnosis of idiopathic cerebrospinal fluid rhinorrhea. The pre- and postcontrast FLAIR subtraction images showed a contrasted protrusion of the right olfactory cleft canal, highlighting the potential practicality and effectiveness of using pre- and postcontrast FLAIR subtraction images in diagnosing idiopathic cerebrospinal fluid rhinorrhea, in conjunction with conventional high-resolution computed tomography and magnetic resonance cisternography. The successful diagnosis of cerebrospinal fluid rhinorrhea allowed for treatment through endoscopic nasal surgery to close the fistula with a positive clinical outcome.

Multidrug-resistant mutations to antiviral and antibody therapy in an immunocompromised patient infected with SARS-CoV-2.

BACKGROUND: Antiviral and antibody therapies for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are being recommended for high-risk patients, but the potential for the development of multidrug-resistant mutations in immunocompromised patients is unclear. METHODS: To investigate the treatment course in cases of prolonged viral shedding in an immunocompromised patient with SARS-CoV-2 infection, we conducted longitudinal measurements of laboratory tests, chest computed tomography (CT) image evaluations, antibody titers, and antigen levels in nasopharyngeal swabs. Furthermore, we performed whole-genome sequencing and digital PCR analysis to examine the mechanisms of drug resistance. FINDINGS: We present a case of a 65-year-old man with a history of malignant lymphoma who was treated with multiple antiviral and antibody therapies, including sotrovimab, remdesivir, paxlovid (nirmatrelvir/ritonavir), and molnupiravir. Initially, viral antigen levels decreased after treatments. However, after the virus rebounded, the patient showed no virologic response. The viral genome analysis revealed a single Omicron subvariant (BA.1.1), which evolved within the host during the disease progression. The viruses had acquired multiple resistance mutations to nirmatrelvir (3 chymotrypsin-like protease [3CLpro] E166 A/V), sotrovimab (spike P337L and E340K), and remdesivir (RNA-dependent RNA polymerase [RdRp] V166L). CONCLUSIONS: Our results indicate that viruses with multidrug-resistant mutations and survival fitness persist in the infected subpopulation after drug selection pressure. FUNDING: This study was supported by the JSPS KAKENHI Early-Career Scientists 18K16292 (Y.H.), Grant-in-Aid for Scientific Research (B) 20H03668 and 23H02955 (Y.H.), the YASUDA Medical Foundation (Y.H.), the Uehara Memorial Foundation (Y.H.), the Takeda Science Foundation (Y.H.), and Kato Memorial Bioscience Foundation (Y.H.).

Lung tropism in hospitalized patients following infection with SARS-CoV-2 variants from D614G to Omicron BA.2.

BACKGROUND: The genetic and pathogenic characteristics of SARS-CoV-2 have evolved from the original isolated strains; however, the changes in viral virulence have not been fully defined. In this study, we analyzed the association between the severity of the pathogenesis of pneumonia in humans and SARS-CoV-2 variants that have been prevalent to date. METHODS: We examined changes in the variants and tropism of SARS-CoV-2. A total of 514 patients admitted between February 2020 and August 2022 were included and evaluated for pneumonia by computed tomography (CT) as a surrogate of viral tropism. RESULTS: The prevalence of pneumonia for each variant was as follows: D614G (57%, 65/114), Alpha (67%, 41/61), Delta (49%, 41/84), Omicron BA.1.1 (26%, 43/163), and Omicron BA.2 (11%, 10/92). The pneumonia prevalence in unvaccinated patients progressively declined from 70% to 11% as the variants changed: D614G (56%, 61/108), Alpha (70%, 26/37), Delta (60%, 38/63), BA.1.1 (52%, 15/29), and BA.2 (11%, 2/19). The presence of pneumonia in vaccinated patients was as follows: Delta (16%, 3/19), BA.1.1 (21%, 27/129), and BA.2 (11%, 8/73). Compared with D614G, the areas of lung involvement were also significantly reduced in BA.1.1 and BA.2 variants. CONCLUSIONS: Compared with previous variants, there was a marked decrease in pneumonia prevalence and lung involvement in patients infected with Omicron owing to decreased tropism in the lungs that hindered viral proliferation in the alveolar epithelial tissue. Nevertheless, older, high-risk patients with comorbidities who are infected with an Omicron variant can still develop pneumonia and require early treatment.

The SARS-CoV-2 virus changes over time with the differing viruses described as variants. The different variants of SARS-CoV-2 have an impact on how easily they infect people and the effects they have on infected individuals. Here, we examined images of the lungs of patients hospitalized with COVID-19 to investigate whether they had pneumonia, a type of swelling in the lung. Compared with the variant found early in the pandemic, the more recent Omicron variant led to a decreased rate of pneumonia in infected individuals. Our findings emphasize the need for early treatment, as pneumonia may progress in older patients or those with other illnesses.

Giant pulmonary bulla causing respiratory compromise in a very low-birthweight infant.

Acquired cystic lung disease in premature infants is a serious respiratory complication, and pulmonary interstitial emphysema (PIE) has been widely reported. We report a rare case of giant pulmonary bulla in an infant treated with bullectomy where chest computed tomography was useful in directing treatment.

Pretreatment 18F-fluorodeoxyglucose Uptake in the Lung Parenchyma Predicts Poor Survival After Stereotactic Body Radiation Therapy in Patients With Stage I Non-Small Cell Lung Cancer.

PURPOSE: In this study, we aimed to evaluate the prognostic value of fluorodeoxyglucose uptake in the lung parenchyma and the presence of subclinical interstitial lung disease on computed tomography as predictive factors for survival following stereotactic body radiation therapy in patients with stage I non-small cell lung cancer. METHODS: We retrospectively evaluated 125 patients with stage I non-small cell lung cancer who underwent stereotactic body radiation therapy at our institute between December 2005 and March 2013 for various demographic and clinical parameters. The fluorodeoxyglucose uptake in the lung parenchyma corrected with computed tomography value (tissue fraction-corrected standardized uptake value) was quantified using fluorodeoxyglucose-positron emission tomography/computed tomography before the therapy. Additionally, the radiological findings of interstitial lung disease on computed tomography were evaluated. The prognostic analyses were performed using the Kaplan-Meier analysis and Cox proportional hazards regression model for univariate and multivariate analyses. RESULTS: The median follow-up period was 39 months. The 3-year overall survival rate was 67.9%, and the 3-year progression-free survival rate was 52.0%. The multivariate analysis indicated that the tissue fraction-corrected standardized uptake value was correlated with the patients' overall survival ( P = .027, hazard ratio: 2.694, 95% confidence interval: 1.109-8.057). The presence of subclinical interstitial lung disease showed no correlation with the overall survival ( P = .535, hazard ratio: 1.256, 95% confidence interval: 0.592-2.473). CONCLUSION: The results indicated that fluorodeoxyglucose uptake in the lung parenchyma, expressed as the tissue fraction-corrected standardized uptake value, was an independent prognostic factor in patients with stage I non-small cell lung cancer who have received stereotactic body radiation therapy.

Prognostic Value of Semiautomatic CT Volumetry in Patients With Stage I Non-Small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy.

OBJECTIVE: The aim of this study was to examine the prognostic value of semiautomated 3-dimensional image analysis-based parameters from pretreatment computed tomography (CT) in patients with non-small cell lung cancer treated with stereotactic body radiation therapy. METHODS: We evaluated 91 patients. We defined 2 parameters: (1) VOL, extracted tumor volume with a threshold ≥ -400 HU; and (2) ATN, the mean CT attenuation value. The maximum standardized uptake value (SUVmax) was recorded as F-fluorodeoxyglucose positron emission tomography/CT parameter. The prognostic values were assessed using the Kaplan-Meier and a Cox proportional hazards analysis. RESULTS: Overall survival and progression-free survival were significantly worse in patients with larger VOL, higher ATN, and higher SUVmax. VOL was an independent indicator of overall survival, whereas ATN was an indicator of progression-free survival, lymph node recurrence, and distant metastasis. However, SUVmax was not an independent prognostic factor for either outcome. CONCLUSIONS: VOL and ATN from 3-dimensional image analysis of CT scans have prognostic values for non-small cell lung cancer patients treated with stereotactic body radiation therapy.

Tracheoesophageal fistula closed by chemoradiotherapy in lung cancer.

A 45-year-old man complaining of cough, dyspnea, and difficulty in swallowing was referred to our hospital. Chest CT scan showed a mediastinal mass compressing the trachea. He was diagnosed with poorly differentiated lung carcinoma by percutaneous needle biopsy. Bronchoscopy and upper gastrointestinal endoscopy revealed a tracheoesophageal fistula (TEF). Long-lasting febrile neutropenia made it impossible to continue chemotherapy, but a course of radiotherapy (total 61 Gy) was completed. The next endoscopy revealed closure of the TEF. Chemoradiotherapy (CRT) has been reported to close TEF in esophageal cancer, but the risk of a CRT-induced worsening of the fistula has dissuaded physicians from using CRT to treat TEF in lung cancer patients. CRT may serve as a palliative treatment for TEF in lung cancer as well as esophageal cancer.

Determination of a standard deviation that could minimize radiation exposure in an automatic exposure control for pulmonary thin-section computed tomography.

PURPOSE: The aim of this study was to determine a standard deviation (SD) that most reduces the radiation dose without sacrificing the diagnostic accuracy of thin-section computed tomography (CT) for clinical use. MATERIALS AND METHODS: A total of 120 patients were examined by multidetector CT. They were assigned to one of four SD groups: 8, 9, 11, and 12. Each SD group consisted of 30 patients. The CT images of the same patients with SD10 that had formerly been examined were used for comparison. Two radiologists independently evaluated the degrees of image noise and diagnostic acceptability of the pulmonary diseases using a point score grading system. We compared the scores between each SD and the SD10 group. RESULTS: Generally, image noise was significantly more prominent in the higher-SD groups. The mean score of diagnostic acceptability was significantly lower in the SD12 group (4.2 ± 1.6) than in the SD10 group (4.6 ± 1.1) group (P < 0.001), whereas no difference was present between the SD8 (4.9 ± 0.7), SD9 (4.8 ± 1.0), and SD11 (4.4 ± 1.5) groups and the SD10 group (4.7 ± 1.1, 4.6 ± 1.4, 4.6 ± 1.1, respectively). CONCLUSION: Thin-section CT with SD12 is not acceptable. SD11 seems to be the setting with the lowest radiation dose while providing acceptable imaging quality for pulmonary thin-section CT.

Localized mucinous bronchioloalveolar carcinoma of the lung: thin-section computed tomography and fluorodeoxyglucose positron emission tomography findings.

PURPOSE: The aim of this study was to evaluate thinsection computed tomography (CT) and fluorodeoxyglucose positron emission tomography (FDG-PET) findings of localized pulmonary mucinous bronchioloalveolar carcinomas (BACs). METHODS AND MATERIALS: From February 2000 to February 2009, there were seven patients with pulmonary localized mucinous BACs that were pathologically confirmed in the surgical specimens. Their CT findings were assessed regarding location, extent (percent) of groundglass opacity (GGO), margin characteristics, and the presence of air-containing spaces and contractive changes. We evaluated the presence of the "angiogram sign" in the patients who underwent enhanced CT. The maximum standardized uptake value (SUVmax) on FDG-PET was measured in four cases. RESULTS: All tumors were located in the lower lobes. The percentages of GGOs ranged from 0% to 70% (average 20%). The tumor margins were well defined in five cases and ill-defined in two cases. Air-containing spaces were seen in all cases. Evidence of contractive change was seen in two of the seven cases. The angiogram sign was identified in one of five patients who underwent enhanced CT. The SUVmax on FDG-PET ranged from 0.93 to 1.97 (mean 1.53). CONCLUSION: The imaging features of localized mucinous BACs include solid or partly solid attenuation, the presence of air-containing spaces, lack of contractive changes, and lower lobe predominance. Additionally, the SUVmax is markedly low on FDG-PET.

Computed tomography appearances of local recurrence after stereotactic body radiation therapy for stage I non-small-cell lung carcinoma.

PURPOSE: The aim of this study was to characterize computed tomography (CT) manifestations of local recurrence after stereotactic body radiation therapy (SBRT) for stage I non-small-cell lung cancer (NSCLC). MATERIALS AND METHODS: A total of 27 stage I NSCLC patients who were treated with SBRT, including 5 patients with local recurrence, were retrospectively analyzed for serial CT examinations. RESULTS: A bulging margin appeared in 4 of the 5 cases (80%) with local recurrence and 1 of 22 cases (5%) without local recurrence. Air bronchograms were seen in 3 of 5 cases with local recurrence and 21 of 22 cases without local recurrence, but they subsequently disappeared in all 3 cases (100%) with local recurrence and in 4 of the 21 cases (19%) without local recurrence. Ipsilateral pleural effusion was observed in all 5 cases (100%) with local recurrence and in 5 of 22 cases (22%) without local recurrence. The opacity increased in size even after 12 months from the completion of SBRT in cases with local recurrence, whereas it decreased or did not change in size in cases without recurrence. CONCLUSION: Local recurrence should be suspected on CT when there was (1) a bulging margin, (2) disappearance of air bronchograms, (3) appearance of pleural effusion, or (4) increase in the abnormal opacity after 12 months.

Thin-section CT of the mediastinum in preoperative N-staging of non-small cell lung cancer: comparison with FDG PET.

PURPOSE: To compare diagnostic capability of preoperative N-staging of lung cancer between thin-section CT of the mediastinum and FDG PET, and 5mm slice thickness CT. MATERIALS AND METHODS: The subjects were 34 patients with lung carcinoma who were examined by both CT and PET, and subsequently underwent surgery between May 2005 and January 2007. CT was carried out with a 16 detector row helical CT scanner. The raw data were reconstructed into 5 mm slice thickness and 1mm slice thickness (thin-section CT). A total of 251 lymph node stations were retrospectively assessed for the presence of lymph node metastasis with thin-section CT, 5 mm CT and PET. In the interpretations of thin-section CT and 5 mm CT, we employed multi-criteria as follows: nodular calcification and intranodal fat as benign criteria, and short-axis diameter more than 10 mm (size criterion), focal low density other than fat, surrounding fat infiltration and convex margin in hilar lymph nodes, as malignant criteria. On PET, maximum standardized uptake value (SUVmax) of 2.5 or more was used as the criterion of malignancy. Sensitivity and specificity were compared between these examinations using McNemar test. RESULTS: Sensitivities and specificities of thin-section CT, 5 mm CT and PET were 25%, 25%, 25%, and 97%, 94%, 98%, respectively. The statistical analysis revealed that the specificity of 5 mm CT was significantly lower than those of thin-section CT (p=0.039) and PET (p=0.006), while no difference was present between thin-section CT and PET. CONCLUSION: Thin-section CT of the mediastinum using multiple criteria was comparable to PET in preoperative N-staging of lung cancer.

Relationship between maximum standardized uptake value (SUVmax) of lung cancer and lymph node metastasis on FDG-PET.

PURPOSE: To evaluate the relationship between SUVmax of primary lung cancers on FDG-PET and lymph node metastasis. METHOD AND MATERIALS: The subjects were a total of consecutive 66 patients with lung cancer who were examined by FDG-PET and subsequently underwent surgery between October 2004 and January 2008. There were 41 males and 25 females, ranging in age from 45 to 83 years with an average of 68 years. The pathological subtypes of the lung cancers consisted of 49 adenocarcinomas, 11 squamous cell carcinomas, 2 adenosquamous carcinoma, 1 large cell carcinoma, 1 small cell carcinoma, 1 pleomorphic carcinoma and 1 mucoepidermoid carcinoma. We statistically compared (1) the mean SUVmax of lung cancer between the groups with and without lymph node metastasis (2) the frequency of lymph node metastasis between higher and lower SUVmax of lung cancer groups that were classified by using the median SUVmax of lung cancer, and (3) evaluated the relationship between the SUVmax of lung cancer and frequency of lymph node metastases, and (4) correlations between the SUVmax of lung cancer and number of the metastatic lymph nodes and pathological n stages. RESULTS: The difference in the average of the SUVmax of lung cancer between the cases with and without lymph node metastases was statistically significant (p = 0.00513). Lymph node metastasis was more frequently seen in the higher SUVmax of lung cancer group (17/33, 52%) than in the lower SUVmax of lung cancer group (7/33, 21%) with a statistically significant difference. There was no lymph node metastasis in lung cancers with an SUVmax of lung cancer less than 2.5, and lung cancers with an SUVmax of lung cancer more than 12 had a 70% frequency of lymph node metastasis. There were moderate correlations between SUVmax of lung cancer, and the number of the metastatic lymph nodes (gamma = 0.404, p = 0.001) and pathological n stage (gamma = 0.411, p = 0.001). CONCLUSIONS: The likelihood of lymph node metastasis increases with an increase of the SUV of a primary lung cancer.

Appearances of pulmonary focal lesions at 0.5-mm slice thickness computed tomography: comparison with 1-mm slice thickness computed tomography.

AIM: This study aimed to evaluate the validity of 0.5-mm thin-section computed tomography (CT) for the assessment of pulmonary nodular lesion in comparison with 1-mm CT. MATERIALS AND METHODS: A total of 38 focal lesions from 30 patients, which were scanned with 0.5- and 1.0-mm collimation, were evaluated regarding the extent of ground-glass opacity (GGO) and well-defined margin, and the presence of pleural indentation, spicula, and internal air density. The frequency of each finding was statistically compared between 0.5- and 1-mm CT using the McNemar test. RESULTS: No statistically significant difference was observed between 0.5- and 1-mm CT for each finding. CONCLUSION: The use of 0.5-mm CT is not justified if the original collimation of multi-detector row CT is near 1 mm.

Appearances of mediastinal and pulmonary hilar lymph nodes on thin-section CT: comparison with 5 mm slice thickness CT.

AIM: This study aimed to evaluate the efficacy of thin-section CT of the mediastinum in the assessment of thoracic lymph nodes in comparison with conventional CT. MATERIALS AND METHODS: A total of 193 CT examinations from 193 patients with suspected pulmonary disease were reconstructed into thin-section CT and conventional CT. The appearances of the lymph nodes were assessed and compared between thin-section CT and conventional CT. RESULTS: Intranodal fat was more often detected on thin-section CT than on conventional CT (P<.001). There were no statistically significant differences in the frequencies of inhomogeneous enhancement and bulging margin of the hilar lymph node. CONCLUSION: Thin-section CT can improve clinical N-staging of lung cancer due to classification of enlarged mediastinal lymph nodes as benign based on identification of intranodal fat.

Chlamydia pneumoniae: comparison with findings of Mycoplasma pneumoniae and Streptococcus pneumoniae at thin-section CT.

PURPOSE: To retrospectively compare thin-section computed tomographic (CT) findings of Chlamydia pneumoniae pneumonia with those of Streptococcus pneumoniae pneumonia and Mycoplasma pneumoniae pneumonia. MATERIALS AND METHODS: Institutional review board and patient informed consent were not required. Twenty-four patients with C pneumoniae pneumonia (17 men, seven women; age range, 19-89 years) underwent thin-section CT; 41 patients with S pneumoniae pneumonia (28 men, 13 women; age range, 19-91 years) and 30 patients with M pneumoniae pneumonia (20 men, 10 women; age range, 16-67 years) were also enrolled. Thin-section CT scans of each patient were retrospectively and independently assessed by two chest radiologists for consolidation, ground-glass opacity (GGO), bronchovascular bundle thickening, nodules, pleural effusion, lymphadenopathy, reticular or linear opacity, airway dilatation, pulmonary emphysema, and bilateral lung involvement. Consensus was reached for disagreements. The frequency of each finding was compared among the three types of pneumonia by using the chi2 test. RESULTS: For C pneumoniae pneumonia, CT demonstrated consolidation in 20 patients, GGO in 13, bronchovascular bundle thickening in 17, nodules in 18, pleural effusion in six, lymphadenopathy in eight, reticular or linear opacity in 15, airway dilatation in nine, pulmonary emphysema in 11, and bilateral lung involvement in 12. Bronchovascular bundle thickening (P = .022) and airway dilatation (P = .034) were significantly more frequent in patients with C pneumoniae pneumonia than in those with S pneumoniae pneumonia. Reticular or linear opacity (P = .017), airway dilatation (P = .016), and associated pulmonary emphysema (P = .003) were significantly more frequent in patients with C pneumoniae pneumonia than in those with M pneumoniae pneumonia. CONCLUSION: C pneumoniae pneumonia demonstrates a wide spectrum of thin-section CT findings that are similar to those of S pneumoniae pneumonia and M pneumoniae pneumonia; airway dilatation and bronchovascular thickening were significantly more frequent in patients with C pneumoniae pneumonia.

[Detectability of lesions in multiplanar reformation (MPR) of the lung].

PURPOSE: To evaluate the diagnostic ability of multiplanar reformation (MPR) images of the lung in comparison with thin-section source CT images. MATERIALS AND METHODS: MPR images were reconstructed for 79 patients with suspected pulmonary disease. Slice thicknesses of source images were 2 mm in 24, 1 mm in 30, and 0.5 mm in 25 cases. The presence of centrilobular nodules, emphysema, bronchiectasis, ground-glass opacity (GGO), consolidation, interstitial thickening, and pulmonary nodule was evaluated on thin-section source images by an experienced chest radiologist to establish gold standards and then subsequently assessed on the MPR images independently by two radiologists. The sensitivity, specificity, and accuracy of each finding were calculated regarding the results of thin-section source images as the gold standards. Accuracy for the detection of findings was also statistically compared among the three groups of different source slice thicknesses using Fisher's exact test. RESULTS: Accuracy for the detection of findings was significantly less (p < 0.05) in 2 mm slice MPR for centrilobular nodule, GGO, and interstitial thickening than in 1 mm or 0.5 mm slice MPR. No statistically significant difference was observed for any of the findings between 0.5 mm and 1 mm slice MPR. Rates of sensitivity, specificity, and accuracy of the MPR images for detection of the findings were 89-100%, 73-95%, and 84-95%, respectively. CONCLUSION: In comparison with thin-section source images, MPR images are comparably sensitive but not as specific for the detection of findings. When producing MPR images, the slice thickness of source images should be less than 2 mm.

[Ability of radiological technologists in charge of CT in a general hospital to detect pulmonary nodules with low-dose CT].

PURPOSE: To examine the ability of radiological technologists (RT) to detect pulmonary nodules with low-dose CT (LCT). MATERIALS AND METHODS: LCT (20 mAs) and normal-dose CT (NCT; 160 mAs) were performed in 60 patients. We used an RT to detect pulmonary nodules with LCT. The results were compared with those of a radiologist who detected nodules with NCT. The diameter and density of the nodules in NCT were compared between the group of nodules detected (DN) by the RT and the group of nodules not detected (NN). RESULTS: 60 nodules were detected with LCT out of 74 nodules detected with NCT (81.1%). Eleven patients had NN as well as DN. The mean diameter of NN was smaller than that of DN, and the density of NN was lower than that of DN. CONCLUSION: The detection of pulmonary nodules with LCT by radiological technologists was acceptable.

[Mucus plugs in the ventral bronchi travel less distance than those in the dorsal bronchi: HRCT observation in third-order or smaller bronchi].

PURPOSE: To examine on HRCT whether there is a difference in the respiratory moving distance of bronchial mucus plugs between ventral and dorsal bronchi. MATERIALS AND METHODS: We examined 36 ventral and dorsal bronchi of the same order in 18 patients with mucoid impaction depicted on HRCT. CT data were obtained by multidetector-row CT. HRCT images of 0.5 mm thickness and 0.3 mm interval were reconstructed. We selected one slice including a mucus plug take-off from each bronchus. When they were not included in a slice, we reconstructed a 1-3 mm slab-thickness MIP image. In these images we measured the distance between the take-off of each bronchus and the hilar margin of the mucus in same-order ventral and dorsal bronchi. We also measured CT attenuation in the ROI of the subpleural region excluding vessels in the same slice. When the differences in distances (delta D) and CT attenuations (delta C) between inspiration and expiration were obtained, we analyzed the correlation between delta D and delta C in ventral and dorsal bronchi, respectively. We also compared delta D between ventral and dorsal bronchi. RESULTS: Mean delta C was 36.26 +/- 2.78 HU. Ventral delta D was 6.46 +/- 3.75 mm, and dorsal delta D was 2.57 +/- 1.59 mm. The correlation between delta C and dorsal delta D was significant (r = -0.78, p < 0.005), whereas that between delta C and ventral delta D was not (r = 0.23, p = 0.64). The ventral delta D was significantly smaller than the dorsal (p < 0.05). CONCLUSION: Between inspiration and expiration in the supine position, mucus plugs in the ventral bronchi travel less distance than those in the dorsal bronchi.