MR Imaging of Hepatocellular Carcinoma: Usefulness of Four-Phase Dynamic Imaging Including Early ArterialPhase

PURPOSE: To evaluate the usefulness of four-phase dynamic MR imaging technique by analyzing the imagingfeatures of hepatocellular carcinoma(HCC). MATERIALS AND METHODS: We reviewed four-phase dynamic MR images of 63lesions in 38 patients. MR imaging of the whole liver on gradient T1-weighted sequence was obtained at 10seconds(phase I), 35 seconds(phase II), 60 seconds(phase III), and 5 minutes(phase IV) after the start ofGd-DTPA(0.1mmol/kg) hand injection(3-4cc/sec) through the vein. We evaluated the degree of lesional contrastenhancement during each phase by comparing surrounding liver parenchyma, and analyzed signal intensity in lesionsover and less 2cm, respectively. RESULTS: The number of lesions showing high signal intensity compared withsurrounding liver parenchyma was 52(83%)during phase I, 30(48%) during phase II, 12(19%) during phase III, and 4(6%) during phase IV. During each phase, the number of lesions with signal intensity lower than that ofsurrounding liver parenchyma was 7(11%), 2(3%), 7(11%) and 21(33%), respectively. Thirty-four lesions wereenhanced only during phase I and eleven during only phase II. In tumors less than 2cm(n=40), more enhanced lesionswere during phase I(n=33) than more during phase II(n=16)(p=.0020). CONCLUSION: During each phase, four-phasedynamic MR imaging is useful for the effective detection of HCC showing varying degrees of contrast enhancement.

Assessment of Focal Liver Lesions with 4-Phase Dynamic FLASH MR Imaging: Usefulness of Early Image Acquisitionfor Characterization of Arterial Phase

PURPOSE: To document the usefulness of early image acquisition using the contrast-enhanced dynacic MR imagingfor characterization of various focal hepatic lesions during the arterial phase. MATERIALS AND METHODS:Seventy-nine patients with 145 focal liver lesions (71 hemangiomas, 59 hepatocellular carcinomas and 15metastases) underwent breathhold dynamic MR imaging using a fast low-angle shot sequence. After obtainingunenhanced T1-weighted images, four phase MR images were obtained 10, 35, 60 and 300 seconds after starting theinjection. Patterns of contrast enhancement were analyzed for each lesion, with an emphasis on first phase images. RESULTS: Forty-two of the 59 HCCs (71%) showed prominent contrast enhancement during the first phase. HCCssmaller than 2cm in diameter showed a more homogeneous enhancement pattern than those which measured 2cm ormore(24/25 vs 12/17;P<.05). Hemangiomas showed a globular enhancement pattern during the same phase in 51 of 71cases (72%), a finding which was more apparent in those whose diameter was 2cm or more(35/54 vs 16/17, p<.05).During the first phase of imaging, 12 of the 15 metastases showed peripheral enhancement of their thick rim. CONCLUSION: The use of early image acquisition on dynamic MR sequences is helpful in character-izing lesionsaccrding to their pattern of contrast enhancement.

Ectopic Thyroid Glands: Clinical and Radiological Features

PURPOSE: To understand the various clinical and radiological features of ectopic thyroid. MATERIALS AND METHODS: This study involved nine ectopic thyroid cases (M:F=2:7; age range, 2-57 years) confirmed by RI thyroidscan between 1993 and 1997. We analyzed one neck ultrasonogram, five CT scans, three MR images, nine Tc-99mthyroid scans, and classified the ectopic thyroid by the basis of these findings. Hormonal abnormalities andsymptoms were evaluated on the basis of medical records. RESULTS: The status of nine patients was found to beeuthyroid (n=6), hypothyroid (n=2) or hyperthyroid (n=1). Among the nine, the ectopic thyroid was lingual (n=6),sublingual (n=3) or thyroglossal (n=1); one patient had both the lingual and sublingual types. Ectopic thyroid wasseen as a well-defined round mass, homogeneously enhanced on CT scan, homogeneously hyperechogenic onultrasonogram and of intermediate signal intense on MRI. All cases showed ectopic radioactivity uptake on Tc-99mthyroid scan. In eight patients, ectopic thyroid was the only hormone-producing thyroid tissue; one had bothnormal thyroid and ectopic thyroid tissue in a thyroglossal duct cyst. Among the six cases of euthyroidism,ectopic thyroid patients with the lingual type complained of throat discomfort. Those with the sublingual typecomplained of palpable neck mass, and preoperative evaluation of thyroglossal duct cyst showed that this wasectopic thyroid. CONCLUSION: Understanding the various clinical and radiologic features of ectopic thyroid canhelp accurate diagnosis and prevent unnecessary surgery or other procedure.

Differential Diagnosis of the Pancreatic Diseases: Significance of Perivascular Changes at Celiac trunk andSuperior Mesenteric Artery on CT

PURPOSE: To classify perivascular change in the celiac trunk and SMA occurring in pancreatic disease and toevaluate its significance in differential diagnosis. MATERIALS AND METHODS: In 73 patients with pancreaticdisease (42, acute pancreatitis; 14, chronic pancreatitis; 17, panreatic cancer) abdominal CT findings wereretrospectively reviewed. We defined " infiltration" as linear or irregular density and "thickening" as presenceof a soft tissue mantle surrounding the vessel, and statistically evaluated the usefulness of these factors forthe differential diagnosis of pancreatic diseases. RESULTS: In 13/42 cases of acute pancreatitis (31%), 4/14 ofchronic pancreatitis (28.6%), and 6/17 of pancreatic cancer (35.3%), periceliac infiltration was observed; thefrequencies were not statistically significant (p=0.916). Peri-SMA infiltration was demonstrated in 9/42 of acutepancreatitis (21.4%), 4/14 of chronic pancreatitis (28.6%), and 5/17 of pancreatic cancer (29.4%); again, thesefrequencies were not statistically significant (p=0.758). Thickening of the celiac trunk and SMA was observed onlyin pancreatic cancer, in 3/17 (17.6%) and 7/17(41.2%) cases, respectively, with statistical significance (p<0.05). CONCLUSION: Thickening of the celiac trunk and SMA is a valuable finding in the differential diagnosis ofpancreatic inflammatory disease and pancreatic cancer. When applied to the differential diagnosis of pancreaticdisease, perivaseular change should be classified as either infiltration or thickening.

Risk Factors of Pneumothorax in Percutaneous Fine Needle Aspiration Biopsy of the Lung

PURPOSE: Percutaneous fine needle aspiration biopsy is known to be a useful diagnostic method for the diagnosis of various pulmonary diseases. Its diagnostic yield is high, and it is safe, but complications such as pneumothorax can occasionally occur. We reviewed the complications arising after needle aspiration biopsy and analyzed the risk factors of pneumothorax. MATERIALS AND METHODS: The medical records and radiographic studies of 157 patients with various pulmonary diseases who underwent needle aspiration biopsy of the lung between 1990 and 1996 were retrospectively reviewed. The clinical features, treatment, and courses of complications were reviewed, and risk factors of pneumothorax such as depth and size of lesion, diameter of needle, number of punctures, and obstructive pulmonary abnormalities were analyzed. RESULTS: Complications occurred in 40 of 157 cases (25.5%), namely pneumothorax in 26 (16.6%), hemoptysis in 11 (7%), hemothorax in two (1.3%), and recurrence of malignancy at the site of aspiration in one (0.6%). When the patients were divided into three groups according to depth of lesion, there were significant difference in the incidence of pneumothorax ; the results were as follows : less than 2cm, 12.9% ; between 2 and 4cm, 24.1% ; and larger than 4cm, 57.1% (p<0.05). In pulmonary function testing, FVC (forced vital capacity) of patients with pneumothorax was less than that of patients without (2.6+/-0.9L vs 3.1+/-0.8L, p<0.05), but FEV1 (forced expiratory volume in 1 second), FEV 1% (percentage of predicted FEV1), FEV1/FVC,and FVC%(percentage of predicted FVC) were not different between the two groups. The incidence of pneumothorax in patients with pleura-attached lesion (9%) was lower than that of those with non-attached lesion (26%, p=0.01). The age of patients, size of lesion, diameter of the needle, guidance methods and number of aspirations showed no significant relationship with pneumothorax. CONCLUSION: In needle aspiration biopsy of the lung, depth of lesion and passage of a needle through aerated lung are significant risk factors of pneumothorax.

Pulmonary asbestosis: radiologic-pathologic brief report

Pulmonary asbestosis is defined as bilateral diffuse interstitial fibrosis of the lungs caused by exposure to asbestos. Many occupations are at risk for asbestos exposure, particularly in the mining, milling, manufacturing, construction, shipbuilding, and automotive industries. Therefore, the prevalence of asbestosis should be fairly widespread. The diagnosis of asbestosis can be made on either clinical or pathological grounds. We recently encountered one case of asbestosis which was confirmed histologically. On HRCT, there was ground-glass opacity with irregular linear shadows, subpleural curvilinear lines and parenchymal bands. Neither plaque nor calcification were noted. The histologic findings observed on open-lung biopsy specimen were well in accord with those in HRCT. Many asbestos-coated bodies were present along with black dust.

Evaluation of Cerebral Aneurysm with High Resolution MR Angiography using Slice Interpolation Technique: Correlation with Digital Subtraction Angiography (DSA) and MR Angiography (MRA)

PURPOSE: There have been some efforts to diagnose intracranial aneurysm through a non-invasive method using MRA, although the process may be difficult when the lesion is less than 3mm. The present study prospectively compare the results of high resolution, fast speed slice interpolation MRA and DSA therapy examing the potentiality of primary non-invasive screening test. MATERIALS AND METHODS: A total of 26 cerebral aneurysm lesions from 14 patients with subarachnoid hemorrhage from ruptured aneurysm (RA) and 5 patients with unruptured aneurysm(UA). In all subjects, MRA was taken to confirm the vessel of origin, definition of aneurysm neck and the relationship of the aneurysm to nearby small vessels, and the results were compared with the results of DSA. The images were obtained with 1.5T superconductive machine(Vision, Siemens, Erlangen, Germany) on 4 slabs of MRA using slice interpolation. the settings include TR/TE/FA=30/6.4/25, matrix 160x512, FOV 150x200, 7minutes 42seconds of scan time, effective thickness of 0.7mm and an entire thickness of 102.2mm. The images included structures from foramen magnum to A3 portion of anterior cerebral artery. MIP was used for the image analysis, and multiplanar reconstruction(MPR) technique was used in cases of intracranial aneurysm. RESULTS: A total of 26 intracranial aneurysm lesions from 19 patients with 2 patients having 3 lesion, 3 patients having 2 lesions and the rest of 14 patients having 1 lesion each were examined. Among those, 14 were RA and 12 were UA. Eight lesions were less than 2mm in size, 9 lesions were 3-5mm, 7 were 6-9mm and 2 were larger than 10mm. On initial exams, 25 out of 26 aneurysm lesions were detected in either MRA or DSA showing 96% sensitively. Specificity cannot be estimated since there was no true negative of false positive findings. When MRA and MPR were used concurrently for the confirmation of size and shape, the results were equivalent to those of DSA, while in the confirmation of aneurysm neck and parent vessels, the concurrent use of MRA and MPR was far superior to the sole use of either MRA or DSA. CONCLUSION: High resolution MRA using slice interpolation technique showed equal results as those of DSA for the detection of intracranial aneurysm, and may be used as a primary nin-invasive screening test in the future.

Chemical Saturation Breath-hold Fast MR Imaging for Characterization of Regional Fatty Changes in Liver

PURPOSE: To assess the usefulness of breath-hold fast MR imaging of liver with fat suppression (FS) by application of chemical saturation technique in the diagnosis of regional fatty changed suspected in sonography. MATERIALS AND METHODS: Thirteen patients who had focal lesions with diffuse, homogeneous signal changes after FS through chemical saturation technique without additional changes of imaging parameter during MR imaging of liver were selected. T1-weighed fast low-angle shot and T2-weighted turbo spin-echo sequences were obtained with or without FS during each single breath-holding session. Subjective changes of signal intensity between the pre-FS and the FS images were compared with the sonographic findings in each lesion. RESULTS: Seven lesions of decreased signal intensity after FS on T1 or T2-weighted images, including three lesions only at FS T1 images, were regarded as focal fat infiltration. All seven lesions had compatible sonographic findings as homogenously echogenic areas. Another six lesions of subjectively increased signal intensity including two lesions only at FS T2 images were regarded as focal fat sparing. All six lesions had sonographic findings as homogenous echo poor areas suggesting focal fat sparing. In cases regarded as fat infiltration, score changes were more prominent at FS T1 images than FS T2 images(p=0.0002). In cases regarded as fat sparing, score changes were more prominent at FS T2 images than FS T1 images(p=0.042). CONCLUSION: Breath-hold fast T1 and T2-weighted MR imaging with and without chemical saturation pre-pulse may be sufficient for characterization of regional fatty changes in the different ferential diagnosis of focal hepatic lesion found at sonography.

Radiology findings of abdominal cystic lymphangioma

Abdominal cystic lymphangioma is a rare congenital malformation of lymphatics. Prognosis is excellent with exact diagnosis and complete surgical excision. The aughors analysed 10 US scans and 9 CT scans of surgically proven cystic lymphangiom for the last 5 years. US scan showed it as a septated cystic mass and 2 cases showed fluid-fluid level. CT scan showed a huge unilocular or multilocular density mass with uniformly thickened septae. A huge unilocular or multilocular cystic mass with uniformly thickened septae could suggest cystic lymphangioma would be differentiated from the other cystic masse.

Radiologic findings of mesoblastic nephroma

The mesoblastic nephroma is a rare benign renal tumor that frequently appears as a neonatal abdominal mass. This benign tumor is composed primarily of connective tissue that growth between intact nephrons and often replaces most of the renal parenchyme. Contrast media within the calyceal systems are seen within the tumor representing function by nephrons trapped within the mass. Prognosis after complete excision is excellent.

131I-MIBG scintigraphy in the evaluation of suspected pheochromocy-toma / 대한핵의학회잡지

No abstract available.

Role of computed tomography in pancreatic trauma

No abstract available.