Radiographic and CT appearances of the major fissures.

The major fissure is an important anatomic landmark in the interpretation of chest radiographs and computed tomographic (CT) scans. At radiography, the major fissures normally appear as hairlines of soft-tissue density; at conventional CT, they typically appear as lucent, hypovascular bands; and at high-resolution CT, they most often appear as sharp lines. The superolateral major fissure usually manifests as a curving edge at the upper lateral lung field with lateral opacity and medial lucency. The vertical fissure line appears as a fine, linear shadow, commencing in or near the costophrenic angle and coursing upward. The superomedial major fissure manifests as a short, obliquely oriented straight line. Progressive widening of the major fissure inferiorly manifests as a triangular area of increased opacity and represents intrafissural fat. Various inflammatory, granulomatous, neoplastic, and abnormal hemodynamic conditions involving the major fissure can affect its imaging appearance. Oblique orientation of the major fissure may complicate radiographic interpretation. The fissure may be incomplete or absent, complicating identification of various diseases. An incomplete major fissure may lead to disease spread, collateral air drift, or the "incomplete fissure sign," a sign that may, however, also be present in cases of complete fissure. Knowledge of the anatomy and normal variants of the major fissures is essential for recognizing their variable imaging appearances as well as related abnormalities.

Unenhanced CT findings of vascular compromise in association with intussusceptions in adults.

OBJECTIVE: The purpose of this study was to evaluate unenhanced CT findings for predicting the degree of vascular compromise in intussusception observed at surgery. MATERIALS AND METHODS: The imaging studies, clinical records, and surgical and pathologic findings in 25 patients with intussusception were reviewed retrospectively. We evaluated six CT findings based on the abnormalities of each component of intussusception. Presence or absence of these findings was compared with the degree of vascular compromise as observed on pathologic examination, such as edema, ischemia, or necrosis. RESULTS: The hypodense layer was observed in 16 of 18 intussusceptions with various degrees of vascular compromise. A fluid collection surrounded by the returning wall, which was revealed to correspond to trapped peritoneal fluid, was observed in eight of nine intussusceptions with ischemia or necrosis. A gas collection surrounded by the returning wall was observed in two of four intussusceptions with necrosis. Free peritoneal fluid coexisted with a fluid collection surrounded by the returning wall in all the intussusceptions except one. Bowel obstruction was observed in six of nine intussusceptions with ischemia or necrosis. The maximum wall thickness was not related to the degree of vascular compromise. CONCLUSION: The CT findings of a hypodense layer in the returning wall, fluid collection in the space surrounded by the returning wall, and gas collection in the space surrounded by the returning wall can be useful in predicting the degree of vascular compromise in intussusception.

[CT-guided needle biopsy of the lung: factors affecting risk of complications].

PURPOSE: To analyze factors influencing the risk of complications associated with CT-guided percutaneous needle biopsy for lung lesions. MATERIALS AND METHODS: Sixty patients, aged 24-85 years (37 men and 23 women), underwent CT-guided needle biopsy. A definite diagnosis was made in 49 of 60 cases (81.7%), including 38 of 43 malignant lesions (88.4%) and 11 of 17 benign lesions (64.7%). Complications associated with biopsy were observed in 35 patients (58.3%). Major complications included pneumothorax (n = 26) and pulmonary hemorrhage (n = 20). Chest tube placement was needed in 5 (19.2%) of 26 pneumothorax cases (8.3% of all biopsies). RESULTS: The high frequency of pneumothorax (43.3%) in this series had several contributing factors, including the presence of pulmonary emphysema, lesion size, and traversal of aerated lung. Chest tube replacement was necessary more frequently in patients with pulmonary emphysema. The number of pleural passes, location of lesions, and size of needles were not correlated with the incidence of pneumothorax. CONCLUSION: The presence of pulmonary emphysema, lesion size, and traversal of aerated lung are the predominant risk factors for pneumothorax in patients with CT-guided lung biopsy.

[CT findings of non-traumatic colorectal perforation].

We retrospectively analyzed CT scans from 23 patients with non-traumatic colorectal perforation. We compared the sensitivity of CT and plain film radiography in the detection of free gas. Free gas was observed in 7 of the 23 cases (30.4%) on plain film radiography and 16 of the 23 cases (69.6%) on CT. Retroperitoneal abscess was demonstrated in 6 of the 7 patients without free gas on CT. Extraluminal air and abscess covered by the omentum and mesenterium were demonstrated in the remaining one patient. The site of perforation was identified in 19 of the 23 patients (82.6%) on CT. CT was useful for demonstrating retroperitoneal free gas, changes in mesenteric fat, extraluminal feces, and tumors. We conclude that CT is indicated in cases of suspected colorectal perforation.

CT of neural plexus invasion in common bile duct carcinoma.

PURPOSE: Our purpose was to analyze the CT findings of neural plexus invasion in common bile duct carcinoma. METHOD: We studied 16 patients with common bile duct carcinoma who underwent surgery. Of these, neural invasion was seen in 10 patients. CT findings were retrospectively reviewed and correlated with the surgical and pathological findings. RESULTS: Irregular masses adjacent to the medial aspect of the uncinate process were observed in 4 of 14 patients with distal common bile duct carcinoma. These lesions extended medially and showed contiguity with the superior mesenteric artery and/or celiac axis, corresponding to neural plexus invasion with desmoplastic change. Increased attenuation of the fat between the common bile duct and the proper hepatic artery was seen in two of two patients with proximal common bile duct carcinoma, associated with neural plexus invasion in the hepatoduodenal ligament. CONCLUSION: The location and spread of neural plexus invasion in common bile duct carcinoma are characteristic and can be diagnosed by CT.

Complications associated with transcatheter arterial embolization for hepatic tumors.

Transcatheter arterial embolization (TAE) is widely used in the treatment of hepatic tumors. A total of 2,300 TAE procedures were performed with a 2-15-mL injection of a mixture or suspension of anticancer drugs and iodized oil, followed by administration of gelatin sponge particles. One or two chemotherapeutic drugs, including doxorubicin hydrochloride (10-30 mg), epirubicin hydrochloride (10-30 mg), mitomycin C (10-20 mg), and cisplatin (25-100 mg), were used for each procedure. Complications were encountered in 4.4% of cases (n = 102) and were related to the use of chemoembolic agents or the manipulation of a catheter or guide wire. These complications included acute hepatic failure (n = 6), liver infarction (n = 4) or abscess (n = 5), intrahepatic biloma (n = 20), multiple intrahepatic aneurysms (n = 6), cholecystitis (n = 7), splenic infarction (n = 2), gastrointestinal mucosal lesions (n = 5), pulmonary embolism or infarction (n = 4), tumor rupture (n = 1), variceal bleeding (n = 3), and iatrogenic dissection (n = 35) or perforation (n = 4) of the celiac artery and its branches. Knowledge of these complications is important for correct diagnosis and appropriate management.

[Usefulness of chest CT in diagnosing pneumonia].

The usefulness of chest CT in diagnosing pneumonia was evaluated by a retrospective review of 110 pneumonia cases in which both plain chest radiograph and CT were obtained. Detection of abnormal opacities on chest radiograph was difficult or impossible in 9 cases (8.2%), requiring CT to detect them. The opacities which appeared consolidative, nodular, small nodular or cavitary on chest radiograph were shown as opacities of similar character on CT. On the other hand, many opacities of patchy, ground-glass or linear/reticular character on chest radiograph were shown as opacities of different character on CT. One case out of 3 of mycoplasma pneumonia, one case each of influenza viral pneumonia and pneumocystis carinii pneumonia and showed rather typical appearance on CT. Detection of pleural effusion on chest radiograph was difficult in 17 (58.6%) of 29 cases in which it was easily detected on CT. In conclusion, CT is useful in diagnosing pneumonia in limited cases, as follows: (1) indistinct abnormal opacity on chest radiograph despite positive clinical signs of pneumonia, (2) patchy, ground-glass or linear/reticular opacities on chest radiograph, (3) confirmation of pleural effusion, (4) close observation of sequential changes of opacity after starting treatment of pneumonia. In contrast, CT is not generally useful in evaluating consolidative opacities on chest radiograph.

Supratentorial arachnoid cyst and associated subdural hematoma: neuroradiologic studies.

CT and MR images of 8 patients with supratentorial arachnoid cyst complicated by subdural hematoma were studied and compared with those of 8 patients who developed nontraumatic subdural hematoma without arachnoid cyst. Of the 8 patients with supratentorial arachnoid cyst, CT and MR disclosed temporal bulging and/or thinning of the temporal squama in all 6 patients with middle fossa arachnoid cysts, and the thinning of the calvaria was evident in another patient with a convexity cyst. Calvarial thinning at the site corresponding to interhemispheric arachnoid cyst was clearly depicted on coronal MR images. In contrast, none of the 8 young patients with nontraumatic subdural hematoma without arachnoid cyst had abnormal calvaria. Temporal bulging and thinning of the overlying calvaria were identified as diagnostic CT and MR features of arachnoid cyst with complicating intracystic and subdural hemorrhage. Radiologists should be aware of this association and should evaluate the bony structure carefully.

[Radiologic diagnosis of pleural mesothelioma].

Five cases of pleural mesothelioma (3 benign and 2 malignant) were evaluated with chest radiograph and CT. A case of benign localized mesothelioma growing within the major fissure, and a case of diffuse malignant mesothelioma encircling the descending thoracic aorta are included among the five cases. Pleural mesotheliomas present a variety of roentgenographic manifestations depending upon the histologic type, the site of origin, and the direction of the extension, and can easily be misdiagnosed as lung tumor, aortic aneurysm, or mediastinal tumor. It is emphasized that pleural mesothelioma should be considered as a differential diagnosis when a mass lesion is found in the mediastinum, hilar region, interlobar fissure, or near the chest wall.