Yasushi Kihara

Magnetic resonance imaging of retained surgical sponges case report

The magnetic resonance imaging (MRI) features of sponges retained postsurgically in three patients are described. MRI depicted these as well-defined round masses, which were of low signal intensity on T1-weighted images and very high signal intensity on T2-weighted images. We scrutinized these masses on T2-weighted images. MRI revealed the low-signal-intensity structures to have wavy, striped, and/or spotted appearances, which raised the suspicion that they might be retained surgical sponges within mass lesions.

Magnetic Resonance Imaging of Bone Marrow Changes after Irradiation

RATIONALE AND OBJECTIVESSignal changes of irradiated bone marrow are thought to represent fatty change. However, more recent studies have indicated that other factors may contribute to these signal changes. We performed animal studies to investigate magnetic resonance (MR) signal change factors in correlation with histologic findings. MATERIALS AND METHODSForty-two male Wister rats were given single doses (3, 8, and 20 Gy) of irradiation. Magnetic resonance imaging (1.5 T) was performed using spin-echo technique. RESULTSIn the acute phase (days 1–3), the T1 time was prolonged, probably secondary to decreased cellularity and edema. After this phase, the irradiated marrow showed marked T1 and T2 shortening that correlated with hemorrhage. In the chronic phase (after day 10), fatty replacement, fibrosis, and regeneration were observed. T2 times were stable in spite of regeneration because of the susceptibility effect of hemosiderin. CONCLUSIONThe MR signal changes of irradiated marrow reflect not only fatty replacement, but hemorrhage as well.

Optimal Timing for Delineation of Hepatocellular Carcinoma in Dynamic CT

Objective The aim of our study was to ascertain the optimal timing and scanning method for detecting hepatocellular carcinoma (HCC) as a high density mass during the early phase of dynamic hepatic CT and to confirm its clinical effectiveness. Materials and Methods We studied retrospectively 39 patients with clinically diagnosed HCC who underwent dynamic hepatic CT. Results All nine lesions that were scanned within 60 s after initiating injections were detected as high density masses. However, 15 of 21 lesions (71%) that were scanned >70 s after initiating injections could not be detected as high density masses. Using helical scanning, which permitted scanning the entire liver within 60s after initiating injections, 27 of 31 lesions (87%) were detected as high density masses. Conclusion We concluded that most HCCs can be detected as high density masses during the early phase of dynamic CT using helical scanning.

Scintigraphic Demonstration of Coexisting Adenoma and Metastasis of the Adrenal Gland in a Patient with Bronchogenic Carcinoma

Metastasis of the adrenal gland is frequently founded In patients with advanced bronchogenic carcinoma. The scintigraphic findings of a patient with adenoma and metastasis in the same adrenal gland is presented.

Pseudo lesions on CTAP secondary to arterio-portal shunts

PURPOSE To clarify the characteristics of the defects on computed tomography (CT) during arterial portography (CTAP) due to arterio-portal shunting (APS). METHOD AND PATIENTS The defects in the hepatic parenchyma on CTAP due to angiography proven APS were characterized according to their configuration, size, sharpness of margins, location of the lesion in the liver, and homogeneity of the lesions. RESULTS Twenty five patients had non-tumor related APS. The shunts were single on angiography in 15 cases and multiple in 10 cases. The APS were due to liver cirrhosis in 22 patients, and to trauma in the other three. The lesions were irregular in shape in nine cases, wedge shaped in six cases, and round in four cases. In three cases both wedge and round lesions were seen. The margins were sharp in five single defects in five cases. The rest of the lesions were judged to have unsharp margins except for one case in which both clear and unclear lesions were present. In 10 cases, internal enhancement of the lesions were seen on CTAP. The location of the defects were central in five cases, peripheral in nine, and both peripheral and central in eight cases. CONCLUSION The parenchymal defects due to APS were typically irregular in shape, with unsharp margins and internal enhancement.

Hepatocellular carcinoma invading the gallbladder: CT, arteriography and MRI findings

Hepatocellular carcinoma (HCC) seldom invades the gallbladder. We report a case of HCC invading the gallbladder that resembled gallbladder carcinoma invading the liver. The diagnosis was confirmed by surgical biopsy. The arteriographic, computed tomography and magnetic resonance imaging findings are presented.

Retroperitoneal leiomyosarcoma. Its MR manifestations.

The magnetic resonance manifestations of retroperitoneal leiomyosarcomas in two patients are described. The tumors were isointense to muscle on T1-weighted images and exhibited a relatively high signal on T2-weighted images. Postcontrast T1-weighted images after the administration of gadolinium-dietilenetriaminepentaacetic acid produced moderate enhancement except in regions of central necrosis.

Hepatic anomalous lobulation demonstrated by liver and hepatobiliary scintigraphy

The use of liver and hepatobiliary scintigraphy for evaluation of the hepatobiliary system in patients with hepatic disease is now widespread. In the present case, the usefulness of liver and hepatobiliary scintigraphy for the diagnosis of liver malformation is described.

Portocaval shunt with unusual CT and MR manifestations.

Objective We investigated the radiological findings of three cases with unusual portocaval shunts. Materials and Methods Three patients with liver cirrhosis and portal hypertension were examined using CT and MRI. CT was performed using intravenous bolus injection of contrast medium in one and with incremental dynamic scanning in two cases. MRI was performed with a 1.5 or 0.5 T superconducting system or with a 0.22 T resistive system in the three patients. Results CT and MRI showed tortuous intrahepatic tubular structures connecting the right posterior portal vein to the inferior vena cava (IVC) in two of the patients. An anomalous vein arising from the extrahepatic portal vein was a tributary connected with the IVC in one patient. Symptoms associated with hepatic encephalopathy were present in two of the patients whose blood ammonia levels were elevated. Conclusion The possibility of the existence of hepatic encephalopathy should be borne in mind when these shunts are detected during abdominal imaging.

Right anterior caudocranial oblique projection for portal venography; its indications and advantages

Right anterior caudocranial oblique (RACCO) projections were evaluated for transarterial portography with digital subtraction angiography. For RACCO projection, the image intensifier was tilted 25 degrees caudally and 30 degrees to the patients right with the patient in the supine position. The abnormal findings imaged in 20 patients were analyzed by types of abnormalities and their locations in the portal venous systems by comparing RACCO and PA projections. The RACCO view was superior to the PA projection for demonstrating either encasements or tumor thrombi in relatively proximal segments of the portal venous branches. Two encasement lesions and a tumor thrombus were imaged only on the RACCO projection. However, the RACCO projection had no definite advantage over the PA view for showing encasements or tumor thrombi in the distal segmental branches. The RACCO projection was superior to the PA view for demonstrating defects in the hepatograms of some hepatic segments (S5 and S8). We concluded that the RACCO view is extremely useful and is indicated for angiographic work-ups of hepatic or biliary lesions when abnormalities are suspected in proximal portal venous branches.