MR imaging of non-cancerous hepatic lesions in Long-Evans cinnamon rats.

We measured MR images of the liver of Long-Evans Cinnamon (LEC) rats with pathologic correlation and assessed the effectiveness of MR imaging (MRI) for diagnosis of noncancerous hepatic lesions. T1- and T2-weighted images of their livers were obtained, and the dynamic and delayed studies after intravenous gadolinium injection were also performed. Cholangiofibrosis showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images. The T2 relaxation time of cholangiofibrosis was significantly prolonged (p < .01), and the signal intensity ratio of this lesion to muscle on T1-weighted images was significantly lower than that of normal liver parenchyma to muscle (p < .01). The lesion was enhanced immediately after gadolinium injection and the enhancement was prolonged. Among three cases of peliosis hepatis identified, one showed heterogeneous intensities on both T1- and T2-weighted images and the other two showed similar intensity pattern to cholangiofibrosis. The characteristic MR appearance of cholangiofibrosis may be useful to distinguish it from hepatocellular carcinoma (HCC).

Peliosis hepatis and neoplastic/dysplastic lesions in aged male Long-Evans Cinnamon rats: MR imaging with pathologic correlation.

The Long-Evans Cinnamon (LEC) rat, an animal model of Wilson's disease, abnormally accumulates copper in the liver. There have been a lot of reports on preneoplastic and neoplastic hepatic tumors in LEC rats, but few studies have been focused on other lesions. The aim of this study was to describe the MR findings of the liver of LEC rats with pathologic correlation to characterize the hepatic lesions developed in them. We measured MR images of the liver of six aged (over the age of 70 weeks old) male LEC rats. Measurements of T(1), T(2)-weighted images, and the dynamic and delayed studies after i.v. gadolinium injection were performed. The rats were sacrificed immediately after the measurements, and the diagnosis was histologically made. We identified seven lesions of peliosis hepatis, three neoplastic/dysplastic lesions, three cysts and one cholangiofibrosis. Peliosis hepatis was characterized as showing a significantly long T(2) relaxation time of 57.9 +/- 13.3 ms (mean +/- standard deviation) compared with 41.3 +/- 1.7 ms in normal liver, and prolonged enhancement after a gadolinium injection. Neoplastic/dysplastic lesions tended to show prolonged T(2), and they showed isointensity on T(1)-weighted images. They were best characterized by early enhancement followed by a rapid wash-out after a gadolinium injection. In conclusions, the frequent occurrence of peliosis hepatis observed in the present study suggests this can be a characteristic lesion in aged LEC rats. The characteristic MR findings enable us to distinguish between peliosis hepatis and neoplastic/dysplastic lesions.

Acute change of exercised muscle using magnetization transfer contrast MR imaging.

We evaluated the acute changes in exercised muscle using magnetization transfer contrast (MTC) MR imaging with a short repetition time sequence. Ten volunteers performed supine ankle dorsiflexion exercise. MTC gradient-recalled echo (GRE) images were obtained before and after exercise at 1.5 T. The effect of MTC was assessed by dividing the signal intensity on MTC GRE images by that on conventional GRE images (M(s)/M0). The signal intensity, M(s)/M0 and cross-sectional area of exercised muscle were all greater at 1-2 min after exercise than immediately after exercise. We propose that this additional increase in these parameters after exercise was due to physiological reflow or hyperemia. Since the M(s)/M0 showed a good correlation with free water content in exercised muscle, this ratio may provide a quantitative variable for evaluating dynamic change of water-macromolecule interaction in skeletal muscle.

Recurrent hepatocellular carcinoma versus radiation-induced hepatic injury: differential diagnosis with MR imaging.

The objective of this study was to assess the value of MR imaging in the differentiation between a recurrent hepatocellular carcinoma (HCC) and a radiation-induced hepatic injury. Nine male patients with suspected recurrence after radiotherapy for HCC underwent T(2)-, T(1)-weighted imaging and Gd-DTPA enhanced dynamic studies. T(2) relaxation times, signal intensity ratios in T(1)-weighted images (WI) and the relative enhancement of the dynamic study were calculated. Recurrent tumors and the irradiated area showed similar image characteristics: hypointense in T(1)-WI and hyperintense in T(2)-WI. T(2) values and signal intensity ratios in the T(1)-WI were not significantly different. In the gadolinium-enhanced dynamic study, a recurrent HCC showed early enhancement, followed by a rapid washout. However, the irradiated liver parenchyma showed hyperintensity from an early phase, and contrast enhancement tended to be more prominent and prolonged at the end of the dynamic studies. The characteristic findings of the dynamic MR study enable us to distinguish between a recurrent HCC and a radiation-induced hepatic injury.

Changes in the liver parenchyma after proton beam radiotherapy: evaluation with MR imaging.

The objective of this study was to describe magnetic resonance (MR) findings with a 1.5T imager for hepatic parenchymal changes after proton beam radiotherapy. Thirty-two patients who received proton radiotherapy with doses of 50-87 Gy underwent MR imaging 1-75 months (mean 22 months) after the start of irradiation. Axial T(2), T(1)-weighted imaging, and a dynamic study after a gadolinium injection were performed. The irradiated areas showed hypointense in T(1)-weighted images, hyperintense in T(2)-weighted images, and intense and prolonged enhancement on the dynamic study (maximum relative enhancement 441.8%+/-263.3 vs. surrounding liver 145.6%+/-67.7, p<0.0001). T(2) values of the irradiated areas were 50.6 to 65.8 msec greater than in the surrounding liver (p<0.005). The values increased with time, being significantly greater 13 months or longer after the beginning of the therapy than after a period of less than 3 months (p<0.05). Pathologic examinations (n = 3) indicated that the irradiated areas were composed of collapsed lobules with hepatic small vein occlusions, and rich extracellular matrices which retained extracellular fluid. MR imaging can demonstrate hepatic parenchymal changes after proton beam radiotherapy, and show the changes are irreversible.

Comparison between magnetization transfer contrast and fast spin-echo MR imaging of degenerative disease of the cervical spine at 0.3 T.

We compared magnetization transfer contrast (MTC) with gradient recalled echo (GRE) magnetic resonance imaging (MRI) and fast spin-echo (FSE) MRI of the degenerative cervical spine at 0.3 T. Fifty patients with suspected degenerative disease of the cervical spine were prospectively evaluated. Multislice sagittal and axial images of the cervical spine were obtained using MTC GRE sequence [repetition time (TR)/echo time (TE)/flip angle = 750/23/25 degrees] and FSE sequence with peripheral gating (TR/effective TE = 2000-4000/120). Quantitatively, FSE showed higher signal-to-noise ratio and superior disk contrast between normal and degenerative disks, while MTC images showed superior contrast-to-noise ratio for the cerebrospinal fluid (CSF) versus cord and superior CSF homogeneity. In qualitative analysis, similar results were obtained. In conclusion, FSE and MTC GRE sequences are MRI techniques of imaging the cervical spine that have different characteristics and supplement each other in the diagnostic imaging of degenerative disease of the cervical spine.

MR imaging of hepatocellular carcinoma.

MR imaging is useful in the diagnosis and early detection of HCC. Characteristic findings for overt HCC, a pseudocapsule and an intratumoral mosaic pattern, are better demonstrated on MR imaging than by other imaging modalities such as ultrasound and CT scanning. Signal intensity on T2-weighted images is useful in evaluating the grade of malignancy of hepatocytic nodular lesions. Hyperintensity on T1-weighted MR imaging is almost always seen in precancerous hepatocellular lesions and in about one third of overt HCC tumors, whereas other hepatic tumors show hypointensity on T1-weighted MR imaging. In evaluating tumor vascularity, gadolinium-enhanced dynamic MR imaging is an essential and powerful tool.

Hepatic arterial infusion of 5-fluorouracil for liver metastases from pancreatic carcinoma: results from a pilot study.

BACKGROUND/AIMS: Liver metastasis is a common progression of pancreatic carcinoma, but an effective chemotherapy has not been established. The purpose of this study was to examine the efficacy and safety of a hepatic arterial infusion of 5-FU in patients with liver metastasis from pancreatic carcinoma. METHODOLOGY: Thirteen patients were enrolled in a pilot study of a hepatic arterial infusion of 5-FU therapy. They received 5-FU for 5 days at a dose of 500 mg/m2/day by continuous hepatic arterial infusion every 4 weeks. RESULTS: One patient showed a partial response, while 6 showed no change. Of these 6 patients, 2 showed a minor response. The overall response rate was 8% (95% confidence interval: 0-22%). Nausea and vomiting were the most common types of toxicity. Three patients (23%) had hepatic arterial occlusion. There were no life-threatening toxicities or complications. The overall median survival time was 15.9 weeks. CONCLUSIONS: Hepatic arterial infusion of 5-FU in patients with liver metastasis from pancreatic carcinoma is tolerable but is minimally effective at this dose and schedule. The schedule of administration should be modified.

Hepatic peribiliary cysts: increases in size and number on computed tomography.

We report a 71-year-old male patient with multiple hepatic peribiliary cysts. The six-year follow-up through computed tomography (CT) imaging revealed increases in the size (from less than 10 mm to more than 38 mm) and number of the cysts.

Fatty mass in the inferior vena cava at CT: lipoma or normal variant?

Fatty mass in the intrahepatic portion of the inferior vena cava (IVC) is an unusual lesion. We describe two cases of fatty mass appearing in the lumen of the IVC on CT and MRI study. We assume that this can be regarded as a benign process, and is mostly a normal variant.

Metastatic tumors in irregular fatty liver mimicking focal sparing.

Two cases of hepatic metastatic tumor occurring in irregular fatty liver are reported. These metastatic tumors appeared as irregularly shaped hyperdense areas and were difficult to distinguish from focally spared areas of irregular fatty liver. Even if areas of focal sparing are irregular in shape, hepatic tumors should be carefully ruled out in patients at high risk for liver tumors.

Magnetization transfer contrast imaging of the cervical spine at 0.3 T.

OBJECTIVE: We assessed the efficacy of magnetization transfer contrast (MTC) imaging of the cervical spine in conjunction with a gradient recalled echo (GRE) technique using a 0.3 T permanent magnet imager. MATERIALS AND METHODS: Seventy patients were prospectively investigated. Multislice sagittal and axial images of the cervical spine with and without MTC were obtained using a GRE sequence (TR/TE/flip angle = 750 ms/23 ms/25 degrees). The contrast-to-noise ratios (C/Ns) for CSF versus cord or disk were calculated for quantitative analysis. Qualitative image analysis was also performed. RESULTS: Both sagittal and axial MTC images had significantly higher C/N values than conventional GRE images. The MTC images showed better differentiation between the CSF and the cord or thecal sac as well as better delineation of the nerve roots. Furthermore, MTC images demonstrated syringomyelia more clearly than conventional images. CONCLUSION: Magnetization transfer contrast images at 0.3 T are effective for diagnosing diseases of the cervical spine.

Hepatic tumors: magnetization transfer MR imaging with gadolinium enhancement.

Thirty patients with 15 hepatocellular carcinomas, 10 metastases, four hemangiomas, and one cholangiocarcinoma underwent magnetic resonance imaging at 1.5 T with T1-weighted, T2-weighted spin-echo (SE) images, gradient-echo (GRE) magnetization transfer (MT) images, and gadolinium-enhanced T1-weighted SE and MT-GRE images. The MT effect and lesion-liver contrast-to-noise ratio (C/N) were calculated and visual assessment (qualitative analysis) performed for unenhanced and enhanced MT-GRE images and enhanced T1-weighted SE images. The C/N values for hepatic adenocarcinomas (seven metastases and one cholangiocarcinoma) and hemangiomas were larger for enhanced MT-GRE images (adenocarcinoma, 8.4 +/- 2.3 [P < .01]; hemangioma 24 +/- 2.1 [P < .05]) than for enhanced GRE images (5.0 +/- 1.9 and 18 +/- 2.7, respectively). These enhancing tumors had the highest scores in the qualitative analysis. Enhanced MT-GRE images showed no advantage for depiction of hepatocellular carcinomas relative to the other images.

Fat tissue: relationship between chemical shift and magnetization transfer.

The middle calves of the legs of 25 volunteers (12 men and 13 women, aged 18-25 years), as well as phantoms, were examined with 1.5-T magnetic resonance imaging. Gradient-recalled technique was combined with magnetization transfer contrast (MTC) and chemical shift imaging. Periodic oscillation of the MTC effect in fat tissue with variation of echo time was identified at the frequency corresponding to the water-fat chemical shift difference.

Preservation of hypervascularity in hepatocellular carcinoma after effective proton-beam radiotherapy--CT observation.

AIM: The aim of this study was to describe persistence of hypervascularity in proton treated hepatocellular carcinoma at serial follow-up computed tomography (CT). METHODS: Four patients with unresectable solitary hypervascular hepatocellular carcinoma underwent 55-82 Gy proton-beam irradiation for a period of 15-47 days. Follow-up CT including plain, enhanced and dynamic imaging was performed for a period of 9-36 months. RESULTS: Good preservation of arterial blood supply while gradual decrease in tumour size was clearly depicted by dynamic CT. CONCLUSION: We believe that preservation of hypervascularity as judged by enhancement at CT and magnetic resonance imaging, does not necessarily mean that radiotherapy in hypervascular malignant tumours has been unsuccessful.

Ductectatic mucinous cystic neoplasms of the pancreas: evaluation with MR cholangiopancreatography.

OBJECTIVE: We performed this study to describe the advantages of MR cholangiopancreatography and its findings in revealing ductectatic mucinous cystic neoplasms of the pancreas. CONCLUSION: MR cholangiopancreatography using both projection and source images can reveal characteristic findings of a ductectatic mucinous cystic lesion of the pancreas and show the presence of the communicating duct between the cystic lesion and the main pancreatic duct.

CT evaluation of hepatic injury following proton beam irradiation: appearance, enhancement, and 3D size reduction pattern.

PURPOSE: The purpose of this study was to investigate the long-term imaging appearances of hepatic injury following proton beam irradiation. The time-attenuation curves, time of appearance and recovery, and 3D size reduction pattern are described in patients of different ages and genders with different irradiation doses, irradiated portals, and Child groups. METHOD: Forty-six patients with hepatocellular carcinoma underwent 50 to 84 Gy proton beam irradiation in periods of 14-52 days. CT including noncontrast and dynamic study was performed every 3 months starting 3 weeks after the end of irradiation. The 3D volume measurement of areas of radiation-induced hepatic injury was performed through incremental dynamic CT images in every follow-up study. CT follow-up study of the patients was done for 12-76 months. RESULTS: Radiation-induced hepatic injury was observed as low attenuation areas on noncontrast CT and enhanced areas on dynamic study in the regions corresponding to the irradiation portals. Of our cases, 67.5% showed the appearance of radiation hepatitis in 3-4 weeks and 95.3% in 3-4 months after the end of irradiation. In both periods, there was a significant delay in the female patients. The time-attenuation curve showed an early and prolonged enhancement of the irradiated regions. The volume reduction pattern of the injured areas was found to be longstanding, exponential, and directed from periphery to the center. CONCLUSION: Early appearance of radiation-induced hepatic injury was found only to be gender dependent, with a tendency to occur with higher irradiated doses; no other parameters affected this phenomenon in our cases. Disappearance of the injured areas, if present, takes a long time (at least 42 months).

Highly enhanced hepatic masses seen on CT during arterial portography: early hepatocellular carcinoma and adenomatous hyperplasia.

BACKGROUND: To describe computed tomographic (CT) features of highly enhanced hepatic masses as seen on CT during arterial portography (CTAP) and to survey the varieties of hepatic lesions associated with such findings. METHODS: CTAP files for 400 patients were reviewed, on the basis of which six patients with highly enhanced hepatic masses were selected. These six patients also subsequently underwent CT during hepatic arteriography (CTHA) on the same day. All the patients had chronic liver damage, which was cirrhotic in five cases. Five had a current diagnosis and one had a history of hepatocellular carcinoma (HCC). RESULTS: Solitary highly enhanced masses were observed on CTAP in three patients, three masses were seen in one patient and multiple (10-12) masses in the other two patients. All the CTAP-enhanced masses except one were round in shape and homogeneous in attenuation. The size of the mass ranged from 6 to 25 mm in diameter. In all except two nodules in one patient, the masses were hypoattenuated on CTHA. On histopathological examination of five nodules in three patients, the nodular lesions were consistent with so-called early HCC (well-differentiated HCC of Edmondson I) in four nodules and adenomatous hyperplasia in the other nodule. CONCLUSIONS: Highly enhanced hepatic masses relative to the surrounding liver parenchyma have been sporadically noted on CTAP, especially in patients with liver cirrhosis. When present, such nodules are typically hypoattenuated on CTHA and histological features are consistent with early HCC and adenomatous hyperplasia.

Von Meyenburg complexes of the liver: imaging findings.

PURPOSE: Our purpose was to present imaging findings of six cases proven or supposed to be von Meyenburg complexes (VMCs) with a basis of reviewing the pathologic literature and to describe imaging points for the diagnosis of typical VMC along with its differential diagnosis. METHOD: Six cases were diagnosed as VMC of the liver with imaging modalities (one had histopathologic proof). Both ultrasound (US) and CT were available for all cases, and MRI was used for three cases. Follow-up with US, CT and/or MRI was performed in five cases. RESULTS: US detected varying abnormalities of the livers in four cases. CT and MRI revealed multiple or numerous intrahepatic tiny (usually < 5 mm) cystoid lesions in all of the cases. The lesions were scattered throughout the livers, and some of them were located more frequently adjacent to the medium-sized portal veins than to the hepatic veins of similar size on CT. Moreover, some lesions were apparently located in the subcapsular areas (up to the hepatic capsules). They were usually irregular in shape and showed no enhancement but increased in number by approximately 80-150% after administration of intravenous contrast medium. The T2-weighted MR images and MR cholangiopancreatography showed the lesions to be much more apparent and to be more numerous than T1-weighted images did. Follow-up of five cases with imaging modalities did not show remarkable change of the lesions. CONCLUSION: Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.

[Distribution and frequency of gastric cancer at the para-cardiac region and fornix].

To clarify the distribution and frequency of gastric cancer in the upper third of the stomach, especially in the para-cardiac region and fornix, we reviewed 634 lesions of all gastric cancers in any location in the University Hospital of Tsukuba University from April 1985 to March 1992. The para-cardiac region was defined as a circular area of 6 cm in diameter around the cardia. We found 56 lesions (8.8%) in the para-cardiac region, almost all of which were concentrated in the distal half of the para-cardiac region, and only three of which (0.47%) were in the fornix. Cancer in the upper third of the stomach tended to occur predominantly in aged male patients, and histologically most of them were classified as having differentiated adenocarcinoma. Since the percentage of advanced cancer at the para-cardiac region was much higher than at any other location, we should be careful to obtain double-contrast images of sufficient quality during the upper gastrointestinal examinations and not to overlook subtle changes in this region during the interpretation of films.