MR Image Fusion-Based Parotid Gland Tumor Detection.

The differentiation of benign and malignant parotid gland tumors is of major significance as it directly affects the treatment process. In addition, it is also a vital task in terms of early and accurate diagnosis of parotid gland tumors and the determination of treatment planning accordingly. As in other diseases, the differentiation of tumor types involves several challenging, time-consuming, and laborious processes. In the study, Magnetic Resonance (MR) images of 114 patients with parotid gland tumors are used for training and testing purposes by Image Fusion (IF). After the Apparent Diffusion Coefficient (ADC), Contrast-enhanced T1-w (T1C-w), and T2-w sequences are cropped, IF (ADC, T1C-w), IF (ADC, T2-w), IF (T1C-w, T2-w), and IF (ADC, T1C-w, T2-w) datasets are obtained for different combinations of these sequences using a two-dimensional Discrete Wavelet Transform (DWT)-based fusion technique. For each of these four datasets, ResNet18, GoogLeNet, and DenseNet-201 architectures are trained separately, and thus, 12 models are obtained in the study. A Graphical User Interface (GUI) application that contains the most successful of these trained architectures for each data is also designed to support the users. The designed GUI application not only allows the fusing of different sequence images but also predicts whether the label of the fused image is benign or malignant. The results show that the DenseNet-201 models for IF (ADC, T1C-w), IF (ADC, T2-w), and IF (ADC, T1C-w, T2-w) are better than the others, with accuracies of 95.45%, 95.96%, and 92.93%, respectively. It is also noted in the study that the most successful model for IF (T1C-w, T2-w) is ResNet18, and its accuracy is equal to 94.95%.

The impact of deep learning on diagnostic performance in the differentiation of benign and malignant thyroid nodules.

AIMS: This study aims to use deep learning (DL) to classify thyroid nodules as benign and malignant with ultrasonography (US). In addition, this study investigates the impact of DL on the diagnostic success of radiologists with different experiences. Material and methods: This study included 576 US images of thyroid nodules. The dataset was divided into 80% training and 20% test sets. Four radiologists with different levels of experience classified the images in the test set as benign-malignant. A DL model was then trained with the train set and predicted benign-malignant for the test set. Then, the output of the DL model for each nodule in the test set was presented to 4 radiologists, who were asked to make a benign-malignant classification again considering these DL results. RESULTS: The accuracy of the DL model was 0.9391. The accuracy for junior resident (JR) 1, JR 2, senior resident (SR), and senior radiologist (Srad) before DL-assisting were 0.7043, 0.7826, 0.8435, and 0.8522 respectively. The accuracy in DL-assisted classifications was 0.9130, 0.8696, 0.9304, and 0.9043 for JR 1, JR2, SR, and Srad, respectively. DL assistance changed the decisions of less experienced radiologists more than more experienced radiologists. Conclusion: The DL model has superior accuracy in classifying thyroid nodules as benign-malignant with US images than radiologists with different levels of experience. Additionally, all radiologists, and most notably less experienced radiology residents, increased their accuracy in DL-assisted predictions.

Deep Network-Based Comprehensive Parotid Gland Tumor Detection.

RATIONALE AND OBJECTIVES: Salivary gland tumors constitute 2%-6% of all head and neck tumors and are most common in the parotid gland. Magnetic resonance (MR) imaging is the most sensitive imaging modality for diagnosis. Tumor type, localization, and relationship with surrounding structures are important factors for treatment. Therefore, parotid gland tumor segmentation is important. Specialists widely use manual segmentation in diagnosis and treatment. However, considering the development of artificial intelligence-based models today, it is seen that artificial intelligence-based automatic segmentation models can be used instead of manual segmentation, which is a time-consuming technique. Therefore, we segmented parotid gland tumor (PGT) using deep learning-based architectures in the paper. MATERIALS AND METHODS: The dataset used in the study includes 102 T1-w, 102 contrast-enhanced T1-w (T1C-w), and 102 T2-w MR images. After cropping the raw and manually segmented images by experts, we obtained the masks of these images. After standardizing the image sizes, we split these images into approximately 80% training set and 20% test set. Hereabouts, we trained six models for these images using ResNet18 and Xception-based DeepLab v3+. We prepared a user-friendly Graphical User Interface application that includes each of these models. RESULTS: From the results, the accuracy and weighted Intersection over Union values of the ResNet18-based DeepLab v3+ architecture trained for T1C-w, which is the most successful model in the study, are equal to 0.96153 and 0.92601, respectively. Regarding the results and the literature, it can be seen that the proposed system is competitive in terms of both using MR images and training the models independently for T1-w, T1C-w, and T2-w. Expressing that PGT is usually segmented manually in the literature, we predict that our study can contribute significantly to the literature. CONCLUSION: In this study, we prepared and presented a software application that can be easily used by users for automatic PGT segmentation. In addition to predicting the reduction of costs and workload through the study, we developed models with meaningful performance metrics according to the literature.

Important aspect of hypoglossal nerve injury following gunshot wound; Can the clivus has a role? A case report.

Cranial nerve palsies after gunshot injury are not uncommon. We report the mechanism of isolated hypoglossal nerve paralysis caused by a gunshot. We report a 74 years old patient in whom a bullet entered through the right nostril and then ended up right occipital condyle. The only neurologic deficit was tongue deviation which resolved in one week. The bullet was not removed. The effect of clival slope may have an importance in this type of injury.

The role of optic nerve sheath diameter measurement on CT in differentiating transient ischemic attack and acute ischemic stroke.

OBJECTIVE: This study aimed to determine if optic nerve sheath diameter (ONSD) measurement on computed tomography could differentiate transient ischemic attack (TIA) from acute ischemic stroke (AIS). Both TIA and AIS are the rings of the same disease chain. To exclude hemorrhagic stroke and stroke mimics in these patients, brain computed tomography (CT) remains the first step imaging modality. PATIENTS AND METHODS: In this retrospective study, ONSDs of patients with TIA and AIS within three hours from symptom onset to initial CT was measured. The right, left, mean, and delta ONSD measurements were compared between AIS and TIA groups. Then diagnostic accuracy metrics were calculated. RESULTS: A total of 196 patients (128 in the AIS group and 68 in the TIA group) were included. Both mean and delta ONSD of AIS patients were higher than those of the TIA group. The area under the receiver operating curve of mean and delta ONSD for predicting AIS were 0.746 with a sensitivity of 82.8% and a specificity of 42.7% (cut-off: 5.00 mm), and 0.826 with a sensitivity of 67.2% and a specificity of 86.8% (cut-off: 0.50 mm), respectively. CONCLUSION: Increased mean or delta ONSD measured on initial CT could alert emergency physicians for an impending stroke.

Comparison of linear versus macrocyclic gadolinium chelates in rat skeletal muscle.

OBJECTIVE: We investigated the effects on skeletal muscle of gadolinium based linear and macrocyclic radiocontrast agents applied at experimental intervals using histopathological methods. METHODS: Thirty-two male Sprague-Dawley rats were included in the study for histopathological analysis. No procedure was performed on the healthy control group. The sham group received 0.1 ml/kg intravenous (IV) saline solution through the tail vein 4 times weekly for 5 weeks. The gadodiamide group received total 2 mmol/kg IV gadodiamide through the tail vein 4 times weekly for 5 weeks. The gadoteric-acid group received 2 mmol/kg IV gadoteric acid through the tail vein 4 times weekly for 5 weeks. RESULTS: We determined no marked apoptotic myofibrils associated withcaspase-3 expression in these two groups. Furthermore, no calcineurin expression was observed in myofibrils in the two groups. However, quantitative analyses revealed a decrease in muscle-fiber area in the gadodiamide and gadoteric-acid groups compared to the control group (Respectively; p=0.001 and p=0.017). CONCLUSION: In our experimental study, linear and macrocyclic GBCAs applied at repeated doses played no role in myofibril damage induced by caspase-3 and calcineurin - nuclear factor of activated T-cells in skeletal muscle tissue.

Comparison of Thalamus Volume on Magnetic Resonance and Cadaveric Section Images.

AIM: To measure and to compare the volume of thalamus using magnetic resonance imaging (MRI) and the anatomical sections. MATERIAL AND METHODS: In this study, 13 brain specimens were used. First, the images were taken in 3 mm sections on MRI, the thickness of the thalamus was measured. Subsequently, 4 mm coronal sections were prepared using a microtome. The thalamic volumes calculated from cadaveric specimens were compared with the measurements obtained using MRI. RESULTS: On MRI, the mean thalamic volumes on the right and left hemispheres were found to be 5843.4 ± 361.6 mm3 and 5377.0 ± 666.2 mm3 respectively. The mean volumes of the cadaveric sections were 5610.8 ± 401.3 mm3 on the right side and 5618.5 ± 604.1 mm3 on the left hemisphere. No statistically significant difference was found between the volume calculated from MRI and that obtained from the cadaveric section (p < 0.05). CONCLUSION: This study shows a correlation between measurement of thalamus volume based on MRI and those calculated from anatomical sections. Our findings support the reliability of DBS procedures using MRI and stereotactic method.

What Are We Missing From Asymmetric Relationship Between the Retinal Nerve Fiber Layer Thickness Profiles and Sphenoid Sinus Volume?

PURPOSE/AIM OF THE STUDY: Detailed analysis of retinal structure such as the retinal nerve fiber layer can be performed by spectral-domain optical coherence tomography (OCT). There are no published studies concerning a relationship between retinal nerve fiber layer and human sphenoid sinus volumes. We investigated this relationship. MATERIAL AND METHODS: Spectral-domain OCT. The peripapillary retinal nerve fiber layer (RNFL) thickness and sphenoid sinus volume estimation of both sides of sex-matched patients were retrospectively analyzed. RESULTS: The mean RNFL thicknesses at the left side (91.8 µm) were significantly smaller than the right side (94.5 µm) (P = 0.040). However, the mean left sinus volume (44.5 cm) is larger than the right side, (34.5 mm) (P < 0.005). Left and right differences of both parameters are statistically significant (P < 0.05). CONCLUSION: There is a negative correlation between mean RNFL thicknesses and mean sinus volumes. To our knowledge, this article is the first report demonstrating the asymmetry relationship between RNFL and sphenoid sinus volumes.

The relation between retrobulbar blood flow and posterior ocular changes measured using spectral-domain optical coherence tomography in patients with obstructive sleep apnea syndrome.

PURPOSE: To investigate the effect of posterior ocular hemodynamics on the retinal nerve fiber layer (RNFL), choroid thickness (CT) and central macular thickness (CMT) in patients with obstructive sleep apnea syndrome (OSAS) and to reveal the association with glaucomatous optic neuropathy. METHODS: The research was planned as a prospective, randomized study. The ophthalmic, retinal and posterior ciliary artery pulsatile index (PI) and resistive index (RI) were measured by colored Doppler sonography. RNFL thickness, CMT and CT were then measured by spectral-domain optical coherence tomography. RESULTS: Sixty subjects were divided into four groups-mild, moderate and severe OSAS and a control group. There were 16 subjects in the control group, 14 in the mild OSAS group, 15 in the moderate OSAS group and 15 in the severe OSAS group. Ophthalmic artery and central retinal artery PI and RI values of the OSAS patients did not show statistically significant difference than those of the control group, but posterior ciliary artery (PCA) PI and RI values were significantly higher. In addition, mean, superior and inferior RNFL thickness values were significantly lower than those in the control group. Moreover, the glaucoma prevalence of the OSAS patients in this study was 6.8% and all of these patients were in the severe OSAS group. CONCLUSION: PI and RI values of the PCA, which supplies the optic nerve, show a linear increase as the apnea hypoxia index values in OSAS. As the grade of OSAS improves, this situation leads to a more serious ischemic optic neuropathy. Furthermore, the prevalence of glaucoma in this study is found to be higher in the severe OSAS group.

Effects of Gadodiamide and Gadoteric Acid on Rat Kidneys: A Comparative Study.

BACKGROUND: Gadolinium-based contrast agents are complex chelates to provide contrast in NRI. However, recent studies have highlighted the deposition of free Gd+3 ion in various tissues. PURPOSE: To evaluate the histopathological and immunohistochemical changes on rat kidney tissue following both macrocyclic (gadoteric acid) and linear (gadodiamide) agents under the hypothesis that gadolinium-based contrast agents (GBCA) lead to toxic, free Gd+3 accumulation in tissues. STUDY TYPE: The local Animal Care Committee approved the prospective animal study. ANIMAL MODEL: Thirty-two healthy Sprague-Dawley male rats were administered 2 mmol/kg gadodiamide and gadoteric acid for the first 4 days for 5 weeks. Group 1 received no drug (control, n = 8) and Group 2 (n = 8) was administered 0.1 ml/kg saline. Group 3 was administered 0.1 mmol/kg gadodiamide and Group 4 (n = 8) was administered 2 mmol/kg gadoteric acid. ASSESSMENT: Biochemical, histopathological, and immunohistochemical changes in testis kidney tissue were evaluated at the end of 10 weeks. STATISTICAL TESTS: Differences between groups were analyzed using the nonparametric Kruskal-Wallis test followed by one-way analysis of variance and the Tamhane test, also followed by Turkey's HSD test. RESULTS: Gadolinium increased serum urea, Ca+2 , and Caspase-3 positive tubular cell number. Larger Bowman capsules shrank proximal and distal tubules were revealed in the gadodiamide and gadoteric acid groups compared to the control group (P < 0.05). Histopathologic examination showed significantly more interstitial fibrosis, amyloid deposits, and vasocongestion in the gadodiamide group than the gadoteric acid and control groups, while the gadoteric acid group demonstrated significantly more leukocytic infiltration with atrophied proximal and distal tubules than the gadodiamide and control groups (P < 0.05). DATA CONCLUSION: GBCA administration causes significant histopathologic changes in kidney tissue. This study advocates additional investigation to assess the in vivo safety of GBCAs. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:382-389.

Can Wideband Tympanometry Be Used as a Screening Test for Superior Semicircular Canal Dehiscence?

OBJECTIVES: We explored whether wideband tympanometry (WBT) could be used as a screening test for superior semicircular canal dehiscence (SSCD), and obtained new WBT data (given that the test is not yet in common clinical use) on patients with SSCD. METHODS: We compared the WBT data of patients clinically and radiologically diagnosed with SSCD in our hospital between 2013 and 2018 to those of healthy volunteers. We compared the resonance frequency (RF), maximum absorbance frequency (MAF), and maximum absorbance ratio (MAR). The t-test was used for statistical analysis with the significance level set to P<0.05. In addition, we used receiver operating characteristic analysis to derive cutoff values for SSCD diagnosis in terms of sensitivity and specificity. RESULTS: Seventeen patients (four with bilateral and 13 with unilateral disease; 17 ears) diagnosed with SSCD and 27 healthy volunteers (47 ears) were included. The mean RFs of the SSCD patients and healthy subjects were 548.7 Hz (range, 243 to 853 Hz) and 935.1 Hz (range, 239 to 1,875 Hz), respectively (P<0.001). The mean MARs of the SSCD patients and healthy subjects were 89.4% (range, 62% to 100%) and 82.4% (range, 63% to 99%), respectively (P=0.005). The mean MAFs of the SSCD patients and healthy subjects were 1,706.3 Hz (range, 613 to 3,816 Hz) and 2,668 Hz (range, 876 to 4,387 Hz), respectively (P<0.001). In terms of SSCD diagnosis, a MAR above 86% afforded 81% sensitivity and 77% specificity; an RF below 728 Hz, 86% sensitivity and 81% specificity; and an MAF below 1,835 Hz, 79% sensitivity and 67% specificity. CONCLUSION: WBT may be a useful clinical screening test for SSCD. The RF and MAF were lower, and the MAR higher, in SSCD patients than in normal controls.

Effects of gadolinium-based MRI contrast agents on liver tissue.

BACKGROUND: MRI with contrast is often used clinically. However, recent studies have reported a high accumulation of gadolinium-based contrast agents (GBCAs) in kidney, liver, and spleen tissues in several mouse models. PURPOSE: To compare the effects on liver tissue of gadolinium-based MRI contrast agents in the light of biochemical and histopathological evaluation. STUDY TYPE: Institutional Review Board (IRB)-approved controlled longitudinal study. ANIMAL MODEL: In all, 32 male Sprague-Dawley rats were divided into a healthy control group subjected to no procedure (Group 1), a sham group (Group 2), a gadodiamide group (Group 3), and a gadoteric acid group (Group 4). FIELD STRENGTH/SEQUENCE: Not applicable. ASSESSMENT: Liver tissues removed at the end of the fifth week and evaluated pathologically (scored Knodell's histological activity index [HAI] method by two histopathologists) immunohistochemical (caspase-3 and biochemical tests (AST, ALT, TAS, TOS, and OSI method by Erel et al) were obtained. STATISTICAL TESTS: Differences between groups were analyzed using the nonparametric Kruskal-Wallis test followed by the Tamhane test, and one-way analysis of variance (ANOVA) followed by Turkey's HSD test. RESULTS: An increase was observed in histological activity scores in sections from rats administered gadodiamide and gadoteric acid, and in caspase-3, AST and ALT values (P < 0.05). In contrast, we determined no change in TOS (P = 0.568 and P = 0.094, respectively), TAS (P = 0.151 and P = 0.055, respectively), or OSI (P = 0.949 and P = 0.494, respectively) values. DATA CONCLUSION: These data suggest that gadodiamide and gadoteric acid trigger hepatocellular necrosis and apoptosis by causing damage in hepatocytes, although no change occurs in total antioxidant and antioxidant capacity. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018;47:1367-1374.

Effects of gadolinium-based contrast agents on submandibular gland tissue in rats.

AIM: The aim of this prospective animal study is to investigate the influence of multiple administrations of macrocyclic ionic (gadoteric acid) and linear nonionic (gadodiamide) gadolinium-based contrast agents (GBCA) on submandibular gland tissue (SGT) of the rats. MATERIAL AND METHOD: Twenty-four Sprague Dawley female rats were included the study. Group 1 was determined as a control group (n = 6). Group 2 was determined as saline group (n = 6). Group 3 was determined as Omniscan group (n = 6) and received only intraperitoneal (IP) 0.1 mmol (0.2 mL/kg)/kg gadodiamide for 8 days. Group 4 was determined as Dotarem group (n = 6) and received only IP 0.1 mmol (0.2 mL/kg)/mg/kg gadoteric acid daily for 8 days. On the 9th day of the administration, the rats were sedated with ketamine and xylazine through IP injection. The right SGT was removed after sedation. Histopathological and immunohistochemical changes in SGT were evaluated. RESULTS: The SGT of the Omniscan and Dotarem groups decreased SGT acini surface area, and serous acinar cells number were observed. On the other hand, no pathology was observed. Mucous acinar cells' caspase-3 positivity for the same markers in Omniscan and Dotarem sections was similar to the control group. However, Omniscan and Dotarem groups serous acinar cells were caspase-3 (+) staining. The intensity of serous acinar cells' caspase-3 (+) for the same markers in Dotarem sections was similar to the Omniscan group. The results also revealed in the analysis of the mean area of the acinus area of the SGT; there were significantly decreased Dotarem group rats when compared to control rats (p < 0.05). CONCLUSION: We consider that numerical increased apoptosis results arise from repeated doses of GBCAs. Being aware of this effect of the contrast agent may have significance for the chronic sialo-adenitis patients group when used for recurrent contrasted MRI for diagnosis of diseases like MS which requires in follow-up. We should be aware about the frequently contrasted MRI in routine investigations.

First report of perforation of ligamentum flavum by sequestrated lumbar intervertebral disc.

Disc fragments are well known to migrate to superior, inferior, or lateral sites in the anterior epidural space, posterior epidural migrated lumbar disc fragments is an extremely rare disorder, 61 cases have been reported to date. However, there were no cases with perforated ligamentum flavum (LF). We report a different case with perforation of ligamentum ligamentum by disc fragment. To the best of our knowledge, this is the first report of perforation LF by a posterior epidural migrated sequester disc.

The effects of choanal atresia on development of the paranasal sinuses and turbinates.

PURPOSE: The objective of this study was to evaluate the volume of paranasal sinuses (PNS) and turbinate in patients with unilateral choanal atresia (CA). MATERIALS AND METHOD: Computed tomography images of PNS in 11 individuals with unilateral CA were evaluated retrospectively. Mucosal thickness and volume of the maxillary, frontal and sphenoidal sinuses were determined, in addition to the volume of the middle and inferior turbinate. The unaffected nasal side of patients was used as a control group for the measurements. The results comprised the measurements of the atresic side compared to those of the healthy side. RESULTS: There was no significant difference between the atresic and healthy side of the nose in patients with CA with respect to mucosal thickness and volume of the PNS (the maxillary, frontal and sphenoidal sinuses) and the middle and inferior turbinate (p > 0.050). CONCLUSION: The complete absence of nasal unilateral airflow had no effect on the development of the PNS and the middle and inferior turbinate. Moreover, mucosal thickness in the sinuses was similar to that in the control group.

Restoration of Anterior Vertebral Height by Short-Segment Pedicle Screw Fixation with Screwing of Fractured Vertebra for the Treatment of Unstable Thoracolumbar Fractures.

BACKGROUND: The treatment of unstable thoracolumbar fractures remains controversial. Long-segment pedicle screw constructs may be stiffer and impart greater forces on adjacent segments compared with short-segment constructs. Short-segment pedicle screw fixation alone may be associated with instrumentation failure. Reinforcement fractured vertebra by the placement of an additional 2 screws at fracture level may be useful in thoracolumbar fractures for restoration of anterior vertebral height. MATERIAL AND METHODS: We retrospectively analyzed 35 patients (21 males, 14 females) with unstable thoracolumbar fractures. The patients were divided into 2 groups. In group I, patients were operated with posterior approach via the use of pedicle screws fixed long (2 levels above and 1 or 2 levels below of the fractured vertebra). In group II patients, short-segment stabilization with additional screwing at fracture level was made. Immediate postoperative radiologic evaluations were done by measuring the correction and maintenance of kyphotic angle at the fracture level, Cobb angle, and height of fractured vertebra. RESULTS: Average local kyphosis angle, anterior kyphotic angle at the fracture level, and Cobb angle were not statistically significantly different in the postoperative period (P > 0.05); however, postoperative anterior height of fractured vertebra was statistically significantly different between the 2 groups (P < 0.05). CONCLUSIONS: We compared a standard long-segment construct with a short-segment construct using instrumentation of the fractured segment. Short-segment pedicle screw fixation with screwing of fractured vertebra in unstable thoracolumbar fracture levels is an effective method to restoring anterior vertebral height for the treatment of unstable thoracolumbar fractures. It also provides anterior column support.

The efficiency of apparent diffusion coefficient quantification in diagnosis of acute cholecystitis and in differentiation of cholecystitis from extrinsic benign gallbladder wall thickening.

PURPOSE: The aim of the current study was to assess the efficiency of the apparent diffusion coefficient (ADC) measurement in diagnosis of acute cholecystitis and in differentiation of cholecystitis from extrinsic benign gallbladder wall thickening. METHODS: Forty patients who were diagnosed to have acute cholecystitis by ultrasonographic examination were included in this study. The control group consisted of 18 patients without symptoms of gallstones and cholecystitis whose gallbladder walls were thickened due to cirrhotic ascites. Both groups were examined using diffusion weighted imaging, and the mean ADC values were compared using Student's t-test. RESULTS: The diagnoses of the 40 patients were proven by histopathological examination. The mean ADC values of patients diagnosed with cholecystitis (1.68 ± 0.36 × 10(-3) mm(2)/s) were significantly lower than the mean ADC values of the control group (2.35 ± 0.24 × 10(-3) mm(2)/s) (p < 0.05). Receiver operating characteristics curve analysis based on ADC revealed a cut-off value of 2.04 × 10(-3) mm(2)/s for the diagnosis of cholecystitis, with a sensitivity of 94% and a specificity of 89.7%. CONCLUSION: ADC value quantification may be an efficient method for making a diagnosis of cholecystitis and in differential diagnosis of cholecystitis from the extrinsic benign gallbladder wall thickening that can be seen during the course of cirrhotic ascites.

The role of HRCT versus CXR in children with recurrent pulmonary infections.

The purpose of this study is to evaluate the role of high-resolution computed tomography (HRCT) versus chest radiography (CXR) in children with recurrent respiratory infections. Fifty-one cases, aged 2 months-13 years, who had a history of recurrent respiratory infections, were examined with CXR and HRCT. HRCT showed that 16/51 of the cases had bronchiectasis. CXR revealed findings of bronchiectasis only in 5 of the 16 cases. HRCT showed peribronchial thickening in 18 cases, whereas CXR showed the same finding in 5 patients. Overall, HRCT showed the underlying pathology and sequel of pulmonary lesions in 22 out of 51 cases, and linear densities in 12. Compared with the CXR, HRCT gives much more information.