The aurora sign: an ultrasonographic sign suggesting parenchymal lung disease.

The objective of this study was to clarify the cause and clinical significance of a large number of ring-down artefact (RA) observed on the dorsal side of the right hepatic lobe on abdominal ultrasound (US). 2000 abdominal US examinations were evaluated to investigate the frequency and number of RA behind the right lobe of the liver. In this study, RA observed by subcostal or intercostal US were described as the "aurora sign" when they were numerous. US findings were correlated with high resolution CT or three-dimensional CT of the right lung base. Experimental study was also performed to investigate the mechanism of the aurora sign. The results were as follows. (1). Aurora sign was noted in 43 patients. In 37 of these 43 patients (86.0%), chest CT or plain radiography revealed diffuse interstitial changes in the right lower lung field. Three-dimensional CT of the lung and the experimental model revealed that the aurora sign derived from the irregularity of air spaces immediately below the pleura associated with interstitial pulmonary disorders. (2). One or more bands of RA were observed in 907 of the 2000 patients (45.4%). Of 177 patients with fatty liver, RA was observed in 14 (7.9%), while of the 1823 patients with no fatty liver, RA was observed in 893 (49.0%). The frequency of RA was significantly different (p<0.001) between the patients with and without fatty liver. In conclusion, parenchymal lung disease should be suspected when the aurora sign is noted on the dorsal side of the right hepatic lobe. However, RAs are rare in patients with fatty liver.

Case report: ciliated foregut cyst of the pancreas mimicking teratomatous tumour.

A ciliated cyst of foregut origin is often found in relation to the tracheobronchial tree and the upper gastrointestinal tract, when it is called bronchogenic cyst and enterogenous cyst, respectively. Cysts of this type rarely occur in the pancreas. We report a case of ciliated foregut cyst involving the pancreas, and mimicking teratomatous tumour on radiology.

Case report: the "aurora sign"--a new sonographic sign of pneumatosis cystoides intestinalis.

Pneumatosis cystoides intestinalis (PCI) is a rare condition characterized by multiple gas-filled cysts of varying size within the intestinal wall. Although the characteristic findings on plain abdominal radiograph, computed tomography (CT), and barium enema have been well described, the sonographic findings have not. We recently encountered a case of PCI in which abdominal sonography disclosed a unique finding. We were able to reproduce the finding experimentally and have coined it the "aurora sign".

Systemic idiopathic fibrosis with inflammatory pulmonary lesions.

Systemic idiopathic fibrosis is characterized by non-suppurative inflammatory diseases of connective tissue, mainly adipose tissue. Although, in this condition, fibrosis may develop in several organs, there have been few reports of fibrosis involving the lung or pleura. We present a case of systemic idiopathic fibrosis associated with inflammatory pulmonary lesions, mimicking lung cancer with multiple pulmonary metastases. Chest CT and MRI showed a spiculated mass around the aortic arch with localized aortic wall thickening and nodules in the lungs. Abdominal CT showed a homogeneous mass around the abdominal aorta, consistent with retroperitoneal fibrosis. Transbronchial lung biopsy of the lesion in the right mid-lung field showed only a few scattered histiocytes accompanying inflammatory and fibrotic change. There was no evidence of malignancy, necrosis, angitis or mycobacterial infection. The lesions almost completely disappeared following prednisone treatment.

Magnetic resonance imaging of rounded atelectasis.

This study describes the magnetic resonance imaging (MRI) findings of rounded atelectasis (RA) and compares them with computed tomography (CT) findings. The study sample comprised 15 cases of RA in which both MRI and CT were performed. The signal intensity of RA was higher than that of muscle and lower than that of fat on T1-weighted images, and similar to or lower than that of fat on T2-weighted images. The atelectatic mass homogeneously enhanced after gadopentetate dimeglumine administration. Structures within and surrounding the RA were clearly depicted on MRI. The pulmonary vessels and bronchi converging toward the area of atelectasis (comet tail sign) were better demonstrated by sagittal or oblique sagittal MRI in six cases. RA and thickened pleurae were more clearly separated on T2-weighted images compared with CT. An infolded visceral pleura was demonstrated as a low-signal-intensity line in seven cases, and a small amount of entrapped pleural effusion was noted in one case. Although MRI should not be performed in all cases of suspected RA, it is useful, especially in delineating the internal structure of RA, such as the infolded visceral pleura.

Pulmonary sclerosing hemangioma: report of a case with emphasis on dynamic MR imaging findings.

We report a case of pulmonary sclerosing hemangioma, a rare benign neoplasm. Marked homogeneous enhancement was noted on postcontrast CT. On the dynamic magnetic resonance (MR) imaging study, peak enhancement occurred 2 minutes after the administration of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA).

Primary ileal volvulus in neonates: radiologic findings in two cases.

Two cases of primary small bowel volvulus in neonates are presented. On abdominal plain radiographs pseudotumor sign was seen in both cases. CT showed intensely distended fluid-filled small bowel loops on the right side of the abdomen and diffuse distention of the proximal small bowel loops with air-fluid levels. US also showed distended fluid-filled loops containing echogenic foci without peristalsis. We consider that CT and US can play important roles in the diagnosis of small bowel volvulus in neonates.

Tuberculous tenosynovitis of the wrist: MRI findings in three patients.

We report recent MRI findings in patients with tuberculous tenosynovitis of the wrist. Marked synovial thickening around the flexor tendons and fluid in the tendon sheath were clearly shown on MRI. Post-contrast study was useful in distinguishing the thick tenosynovium from the surrounding structures and fluid in the tendon sheath. The well-enhanced tenosynovium was also seen in the carpal tunnel in all cases. On the basis of these findings, we could easily distinguish tenosynovitis from other soft-tissue-mass lesions, such as tumors or infected ganglia. Tuberculous tenosynovitis is often not diagnosed early, and its differentiation from soft tissue tumors may be clinically difficult. MRI, particularly post-contrast study, is useful for early diagnosis of, and planning treatment for, tuberculous tenosynovitis.

Spontaneous perforated pyometra presenting as pneumoperitoneum.

BACKGROUND: Spontaneous perforated pyometra presenting as pneumoperitoneum is extremely rare. CASE REPORT: An 80-year-old Japanese female with spontaneous perforating pyometra presenting as pneumoperitoneum is reported. The patient came to our institute with severe abdominal pain. Routine abdominal examination showed muscular defense, and plain chest roentgenograms revealed infradiaphragmatic free gas. Subsequent computed tomography also demonstrated pneumoperitoneum. Laparotomy was performed on the basis of a tentative diagnosis of perforation of the gastrointestinal tract but revealed a perforated pyometra. A simple hysterectomy was performed. The histological diagnosis of the surgical specimen was acute endometritis without neoplasm. The present report is the third case of spontaneous perforated pyometra with pneumoperitoneum to date. CONCLUSION: Although uterine disease presenting as pneumoperitoneum is rare in elderly patients with an acute abdomen, the possibility of a perforated pyometra should be considered in the differential diagnosis.

Spontaneous rectus sheath hematomas: clinical and radiological features.

We reviewed the clinical and radiological features in eight patients with spontaneous rectus sheath hematoma (RSH). The diagnosis was confirmed at surgery in four patients, and spontaneous resolution occurred in the other four. All patients were elderly adults. Acute abdominal pain and a palpable mass after muscular strain, such as coughing or twisting, were features highly suggestive of RSH. Sonographically, these hematomas may be confused with abdominal wall tumors. On CT scans, a hyperdense mass posterior to the rectus abdominis muscle with ipsilateral anterolateral muscular enlargement is considered characteristic of acute RSH, although chronic RSH may be isodense or hypodense relative to the surrounding muscle. MRI is very useful in the diagnosis of RSH, which is demonstrated as a high signal intensity area on both T1- and T2-weighted images, especially when the CT findings are not specific for RSH.

Insulinoma: correlation of short-TI inversion-recovery (STIR) imaging and histopathologic findings.

We studied the value of short-TI inversion-recovery (STIR) imaging for the localization of pancreatic insulinoma. Four patients (three women and one man aged 35-65 years) with surgically proven insulinoma were included in this study. All patients were examined by MR imaging with spin echo (SE) and STIR sequences. The STIR images were compared with the histopathologic findings in each case. In two patients, the tumors were markedly hyperintense on STIR images, and a 5-mm insulinoma was depicted only by this imaging method in one of the two. In the other two patients, 10-mm insulinomas were only slightly hyperintense on STIR images. The latter tumors had a higher content of collagen fibers than the former, indicating that the amount of collagen influences the signal intensity of insulinoma. Despite some limitations, STIR imaging is a useful noninvasive method for the localization of pancreatic insulinoma.

[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 findings of invaginated mesentery in adult intussusception].

The CT findings of invaginated mesentery in adult intussusception were analyzed in 12 patients (three patients with four small bowel intussusceptions and nine patients with nine large bowel intussusceptions). In all small bowel intussusceptions, the neck was located near the superior mesenteric artery and vein (SMA & SMV) and showed a medial opening, and the vessels in the neck showed a continuity to the left side of SMA & SMV. In most of the large bowel intussusceptions, the neck was located distant from SMA & SMV, and the vessels in the neck did not show continuity to SMA & SMV. The difference in CT findings between small and large bowel intussusception is attributed to the difference in mesenteric anatomy; the small bowel and its mesentery move freely in the peritoneal cavity, whereas the large bowel is partially fixed to the retroperitoneum.

[Rounded atelectasis with emphasis on its wide spectrum].

While rounded atelectasis (RA) is considered to be rather common in the United States and Europe, the total number of RA cases reported from Japan still remains approximately 30. We have long been aware that there are many variations in the radiographic appearance of so-called RA and that RA has never been clearly defined. We retrospectively reviewed 22 cases collected as RA and its variants from several institutions. We defined RA as "peripheral atelectasis mimicking tumor secondary to shrinkage or bending of the pleura of various degrees, and accompanied by lung distortion." The diagnostic criteria of typical RA include (1) peripheral tumoral shadow in contact with pleural effusion or thickened pleura, (2) acute angle between the pleura and the shadow, (3) convergence of the pulmonary vessels and bronchi and (4) volume loss of the affected lobe. However, there are cases which lack some of these criteria but are considered to be included in the broad category of RA. We propose that RA should be considered to be an entity having a wide spectrum. Typical lesions showing "cranial tilting" of Hanke are on one side of the spectrum and small linear or strand shadows extending from the thickened pleura are on the other.