Rim-like Enhancement Research Articles

Hepatic malignancies: Correlation between sonographic findings and pathological features.

Ultrasonography (US) findings are inevitably based on pathological features. Knowledge of the pathological features of hepatic malignancies such as hepatocellular carcinoma (HCC), liver metastasis and intrahepatic cholangiocarcinoma is essential for correct US diagnosis and appropriate management. One type of hepatocarcinogenesis is step-wise development from a low-grade dysplastic nodule (DN), high-grade DN, high-grade DN with malignant foci, and well-differentiated HCC, to classical HCC. The intranodular blood supply changes in accordance with this progression. Moreover, the malignant potential tends to change as the macroscopic configuration progresses. Therefore, typical US findings of advanced HCC are a mosaic pattern, septum formation, peripheral sonolucency (halo), lateral shadow produced by fibrotic pseudocapsule, posterior echo enhancement, arterial hypervascularity with dilated intratumoral blood sinusoids, and perinodular daughter nodule formation. Bull's eye appearance is a common presentation of metastases from gastrointestinal (GI) adenocarcinomas, and represents histological findings that show an area of central necrosis surrounded by a zonal area of viable tumor. Thick zonal area reflects the layer of viable cells that are fed by minute tumor vessels. US imaging features of liver metastases from the GI tract are as follows: Bull's eye appearance, multiple masses, irregular tumor border, arterial rim-like enhancement, and hypoenhancement in the late vascular phase. Most intrahepatic cholangiocarcinomas are ductal adenocarcinomas. The bile ducts peripheral to the tumor are usually dilated because of obstruction by tumors. US imaging features of mass-forming cholangiocarcinoma are as follows: peripheral bile duct dilatation, irregular tumor border, arterial enhancement due to minute intratumoral blood sinusoids, and hypoenhancement in the late vascular phase.

Dynamic Evolutionary Changes in Blood Flow Measured by MDCT in a Hepatic VX2 Tumor Implant over an Extended 28-day Growth Period: Time-Density Curve Analysis

The enhancement pattern of malignant tumors has been studied in short-term animal models (7-14 days), but the reported results have been variable and inconsistent. The purpose of this study was to investigate the changing blood flow characteristics of VX2 tumors implanted in rabbit livers with contrast-enhanced multidetector computed tomography (MDCT) to establish a predictable pattern of vascular evolution over an extended 28-day growth period. VX2 carcinoma was implanted in livers of 10 male New Zealand White rabbits. Dynamic CT (2/seconds x 60 seconds) was conducted on days 7, 14, 21, and 28 after tumor implantation. Enhancement parameters of time-density curve (TDC), time to start (T0), time to peak (TP), maximum enhancement (DeltaH), slope of enhancement (SLe), and washout (SLw) in tumor center, tumor rim, and normal liver were analyzed. Tumor samples corresponding to CT images of one tumor on days 14 and 21 and seven tumors on day 28 were stained with hematoxylin and eosin and anti-CD31 monoclonal antibody. The relationship between enhancement parameters and histology parameters (thickness of tumor border, extent of blood stasis, and luminar vessel density) was analyzed. Consistent growth, appearance, and vascular changes occurred in 7 of 10 animals over the 4-week observation period. Peripheral rim-like enhancement was noted in CT images. TDC analysis showed that tumor rim enhancement was pronounced and more rapid than normal liver initially but this difference diminished with tumor progression. The SLe, SLw, and DeltaH decreased from 10.03 +/- 3.25 Hu/second, 0.42 +/- 0.25 Hu/sec, and 58.00 +/- 25.27 Hu on day 7 to 5.86 +/- 2.73 Hu/second, 0.10 +/- 0.13 Hu/second, and 37.78 +/- 8.89 Hu/second on day 28, respectively. TP increased from 12.71 +/- 4.85 seconds on day 7 to 25.57 +/- 7.75 seconds on day 28. No significant changes were noted on the TDC parameters in normal liver. The maximum density difference between tumor rim and normal liver (D(rim-liver)) appeared 10.5 +/- 2.1 seconds after contrast injection. The maximum D(rim-liver) decreased from 54.33 +/- 37.86 Hu on day 7 to 11.16 +/- 13.03 Hu on day 28. On histological analysis, viable tumor cells were found in tumor rim with few luminar vessels. The tumor border showed desmoplastic reaction, vascular dilation and proliferation, inflammatory cell infiltration, and blood stasis. These findings were more obvious on day 28 than those on day 14. TP showed significant positive correlations with the extent of blood stasis in tumor border and adjacent liver and the maximum thickness of the tumor border (r = 0.945 and 0.893 respectively, P < .05). The rabbit VX2 liver tumor is a hypovascular tumor with perilesional enhancement over its lifespan as imaged by MDCT. Consistent changes in the measured vascular parameters correlated with the size/age of the tumor implants. These findings suggest that the accuracy of CT enhancement imaging for VX2 liver tumor detection might be decreased with tumor development.

Renal cell carcinoma: real-time contrast-enhanced ultrasound findings

To investigate the findings of renal cell carcinomas (RCCs) on contrast-enhanced ultrasound (CEUS). CEUS features of 84 RCCs confirmed by pathologic examination in 81 patients were retrospectively analyzed. A contrast-specific mode and a sulfur hexafluoride-filled microbubble contrast agent were used for CEUS. The enhancement pattern, extent, and dynamic change in the cortical, corticomedullary, and late phases were evaluated. On CEUS, the emergence of tumor enhancement was earlier in two nodules (2.4%), simultaneous in 71 (84.5%), and later in 11 (13.1%), in comparison with the adjacent renal cortex. Seventy-four RCC nodules (88.1%) showed hyper-enhancement (n = 2) or iso-enhancement (n = 72) during the cortical phase, and the remaining 10 (11.9%) showed hypo-enhancement. Twenty-three nodules (27.4%) showed homogeneous enhancement and 61 (72.6%) inhomogeneous enhancement. In the corticomedullary phase, the nodules showed hypo-enhancement in 68 (81.0%) and iso-enhancement in 16 (19.0%). In the late phase, all RCCs showed the same enhancement pattern as that shown in the corticomedullary phase. Seventy-two (85.7%) nodules showed a clear perilesional rim-like enhancement in late phase. Hyper- or iso-enhancement during the cortical phase, subsequent washout in late phase, inhomogeneous enhancement, and perilesional rim-like enhancement are clues for RCCs, which might be useful for characterization of RCCs.

Differentiating Focal Eosinophilic Necrosis of the Liver From Hepatic Metastases Using Unenhanced and Portal Venous Phase Computed Tomographic Imagings

To evaluate the usefulness of computed tomographic (CT) predictors on portal venous phase images and a new CT predictor on unenhanced images in differentiating focal eosinophilic necrosis (FEN) from hepatic metastases. Computed tomographic findings were analyzed in 20 patients with FEN (n = 84) and 23 patients with hepatic metastases (n = 81). Computed tomographic features were compared using univariate and multivariate analyses to determine significant findings. An irregular shape, a subtle low attenuation, a fuzzy margin, and absences of a contour bulging and a rimlike enhancement on the portal venous phase images and absence of a discernable low attenuation on the unenhanced images were significant variables favoring FEN in univariate analysis. In multivariate analysis, no discernable low attenuation on the unenhanced images and an irregular shape and a subtle low attenuation on the portal venous phase images were the variables independently favoring FEN. Not only portal phase images but also unenhanced images can be helpful to differentiate FEN from hepatic metastases.

1133: Contrast-Enhanced Real-Time Harmonic Gray Scale Ultrasound Findings of Peripheral Intrahepatic Cholangiocarcinoma

To characterize the contrast-enhanced real-time harmonic gray scale ultrasound (CEUS) findings of peripheral intrahepatic cholangiocarcinoma (ICC) and to access the usefulness of CEUS in the diagnosis of ICC. Retrospective analysis of 33 patients with ICC who had undergone both preoperative CEUS. Sonographic examinations were performed with Technos DU8 and Philips IU22 ultrasound instruments and ultrasound contrast agent SonoVue. All ICC lesions enhanced in the arterial phase with an initial time of 14.59s±3.77s(5s-20s) and a peak enhancement time of 21.39s±5.00s(10s-30s). The time of lesions displaying isoechoic and hypoechoic comparing with the hepatic parenchyma were 29.84s±7.69s(14s-52s) and 40.13s±15.55s(20s-90s), respectively. Then all lesions presented hypoechoic in the portal and the late phase. Of the 33 patients,16 (48.5%) cases showed whole-lesion enhancement and 17 (51.5%) cases showed rim-like or thick bandlike enhancement. There were 63.6%(21/33) cases showing progressive dendritic and concentric filling of the contrast agent and 81.8%(27/33)cases showing heterogeneous enhancement during the peak enhancement. Of all patients, 51.5% (17/33) cases presented lobular appearance during the CEUS examination especially in the portal phase and parenchyma phase. The diagnostic accuracy of CEUS was 87.9% (29/33) if the diagnostic feature included early wash-in and wash-out, progressive dendritic enhancement and/or heterogeneous enhancement. There are some specific findings on CEUS which is useful in the diagnosis and differential diagnosis of this disease.

Thoracic textilomas after myocardial revascularisation: typical CT findings

The objective of this work was to report the tomographic findings in five cases of intrathoracic textilomas. The CT scans of five patients presenting with textilomas after being submitted to thoracotomy for myocardial revascularisation were reviewed retrospectively. Two chest radiologists studied the scans independently, and decisions concerning the CT findings were made by consensus. In each of the five cases, the imaging findings were similar and showed lesions resembling an extrapulmonary mass and well-defined contours situated at the marginal posterior pleural surface. In four of the five cases, a low-density centre and peripheral rim-like enhancement were observed after administration of contrast media. The suspicion of textiloma should be raised when a patient with a history of previous myocardial revascularisation surgery presents with an extrapulmonary mass in close contact with the posterior pleural surface.

Comparison of FDG-PET, PET/CT, and MRI for follow-up of colorectal liver metastases treated with radiofrequency ablation: initial results

Morphologic imaging after radiofrequency ablation (RFA) of liver metastases is hampered by rim-like enhancement in the ablation margin, making the identification of local tumor progression (LTP) difficult. Follow-up with PET/CT is compared to follow-up with PET alone and MRI after RFA.

Lumbar Congestive Myelopathy Mimicking Neoplasia Without Concurrent Vascular Malformation -Case Report-

A 78-year-old male presented with congestive myelopathy manifesting as progressive gait disturbance following conservative therapy for lumbar spinal canal stenosis, with suspected spinal cord tumor in the conus medullaris. His past medical history was unremarkable and he was not aware of any traumatic injury in the back or infectious disease. On admission, he had clumsy hand, moderate paraparesis, significant sensory disturbance below the L5 level, and severe vesicorectal dysfunction. The deep tendon reflex was promoted in the upper extremities, but poorly induced in the lower extremities. Blood examination found no abnormalities including values of tumor markers. Cerebral, cervical, and thoracic magnetic resonance (MR) imaging revealed no contributory pathology without spondylotic change at the C3-C6 levels. Lumbar MR imaging showed fusiform swelling of the cord from the T10 to T12-L1 levels, with rimlike enhancement at the T12-L1 levels by gadolinium. The patient underwent surgery. Intraoperatively, the dorsal surface of the affected cord was pale, not swollen, and sparsely vascularized without tortuous vessels. Midline myelotomy caused escape of creamy material that was identified as necrotic neural tissue. A collapsed vessel, located on the surface of the cord, was histologically identified as a thrombosed vein. The histological findings were compatible with spinal infarction caused by congestive myelopathy. Whole craniospinal and iliac angiography performed postoperatively failed to reveal any dural and paraspinal vascular malformation. His paraparesis, sensory disturbance, and vesicorectal dysfunction improved significantly after surgery. Congestive myelopathy may be caused by various angiographically occult etiologies other than dural arteriovenous fistula.

Magnetic resonance imaging of primary cerebral gliosarcoma: a report of 15 cases

Gliosarcomas are rare tumors with mixed glial and mesenchymal components. Many of their radiologic features resemble those of other primary brain malignancies. To investigate the magnetic resonance (MR) imaging features of gliosarcomas. We retrospectively reviewed the MR images, pathology reports, and clinical information of 11 male and four female patients aged 15-71 years to evaluate the location, morphology, enhancement, and other features of their pathologically confirmed gliosarcomas. Apart from one tumor in the right cerebellar hemisphere, all were supratentorial. Two tumors were intraventricular, and four involved the corpus callosum. The tumors were well demarcated, with an inhomogeneous or cystic appearance and moderate-to-extensive surrounding edema. Thick walls with strong rim and ring-like enhancement were observed in 13 (87%). Seven (47%) showed intratumoral paliform enhancement. Gliosarcoma demonstrates certain characteristic MR features, such as supratentorial and peripheral location, well-demarcated, abutting a dural surface, uneven and thick-walled rim-like or ring enhancement, as well as intratumoral strip enhancement. These findings, combined with patient age, can aid the differential diagnosis of gliosarcomas from more common primary brain tumors.

Neuroendocrine Tumors: Characterization with Contrast-Enhanced Ultrasonography

The aim of this study was to characterize the ultrasonographic features of neuroendocrine tumors (NET) and their metastases with contrast-enhanced ultrasonography (CEUS) and to compare this to clinical data. During a period of 5 years, 82 patients with 83 histologically proven NET were prospectively examined using conventional US and pulse inversion US with a second generation contrast agent (SonoVue, Contrast Pulse Sequencing) focusing on the arterial (10-20 s p. i.), capillary (20-25 sec p.i.), portal venous (25-120 sec p.i.), and late phases (>120 sec p.i.). 69 patients had metastases in the abdominal tract, including eight patients with poorly differentiated neuroendocrine carcinomas with high-grade behavior. In 31 patients the proliferation index (MIB-1) of the NET was < or = 2%, in 46 patients > 2%, in 6 patients > or = 20%. Thirteen patients had one primary lesion without metastases. In NET of the lung, stomach, and colon we found only hypoechoic or isoechoic liver metastases. NET of the small intestine and pancreas represented hypoechoic, isoechoic, and/or hyperechoic liver lesions, sometimes combined. Insulin producing tumors (6) had hypoechoic metastases. Necrotic areas (25/83) were detected after interferon therapy, embolization, systemic chemotherapy, and radiofrequency ablation of liver metastases, but did not develop after somatostatin receptor radionuclide therapy. In large NET (> 3 cm) with a proliferation index of > 2%, necrotic areas appeared spontaneously. In 93% (77/83) of the cases the NET and their metastases showed an early arterial influx of microbubbles. Rim-like contrast enhancement occurred during the capillary phase in 78% (65/83) of all lesions, and hypervascularization occurred during the arterial phase and at the beginning of the capillary phase in 95% (79/83). The hypervascularized tissue was found in the primary lesions, in liver, lymph node metastases and any kind of abdominal metastases. In liver metastases with a proliferation index >2%, tumor arteries showed a chaotic growth pattern. In 93% (77/83) the NET lesions appeared as dark "defects" at the beginning of the late phase. CEUS with CPS demonstrates typical NET imaging characteristics. Differences in imaging features may depend on their primary lesion, size, proliferation marker, and extent of the degenerative changes. In most cases real-time CEUS may replace other imaging techniques.

Posterior Fossa Dural Arteriovenous Fistula As a Probable Cause of Congestive Myelopathy -Case Report-

A 62-year-old female suffered severe occipitalgia followed by progressive tetraparesis and bulbar symptoms, although tinnitus in the left ear persisting for more than 1 year resolved spontaneously after the onset. Cerebral magnetic resonance (MR) imaging revealed swelling in the lower brainstem, and cervical T(2)-weighted MR imaging showed diffuse intramedullary hyperintensity in the medulla oblongata extending downward to the upper thoracic cord. Rim-like enhancement was localized at the C2 level after gadolinium administration. Extensive blood and cerebrospinal fluid examinations and whole body scintigraphy showed no indications of the underlying pathology. She underwent open biopsy for histological verification and decompressive maneuver to the cord. Sparse arterial distribution, and collapsed and partially thrombosed veins were recognized on the dorsal surface of the cord. Midline myelotomy yielded creamy fluid that proved to be necrotic tissue. Histological examination found the venous wall was thickened with lymphocytic infiltration. Her tetraparesis showed mild improvement postoperatively with marked resolution of the intramedullary hyperintensity on MR imaging. Postoperative cerebral angiography revealed a posterior fossa dural arteriovenous fistula (dAVF) fed by the left ascending pharyngeal and occipital arteries, with venous reflux to the ipsilateral inferior petrosal sinus. No venous drainage was found via the perimedullary vein. The dAVF was completely obliterated by transvenous coil embolization. We considered that the dAVF might have caused the congestive myelopathy. Decompressive maneuver may provide effective management for necrotizing myelopathy in selected cases.

Comparison of FDG-PET, PET/CT and MRI for follow-up of colorectal liver metastases treated with radiofrequency ablation: Initial results

Purpose Morphologic imaging after radiofrequency ablation (RFA) of liver metastases is hampered by rim-like enhancement in the ablation margin, making the identification of local tumor progression (LTP) difficult. Follow-up with PET/CT is compared to follow-up with PET alone and MRI after RFA. Methods and materials Sixteen patients showed 25 FDG-positive colorectal liver metastases in pre-interventional PET/CT. Post-interventional PET/CT was performed 24 h after ablation and was repeated after 1, 3 and 6 months and then every 6 months. PET and PET/CT data were compared with MR data sets acquired within 14 days before or after these time points. Either histological proof by biopsy or resection, or a combination of contrast-enhanced CT at fixed time points and clinical data served as a reference. Results The 25 metastases showed a mean size of 20 mm and were treated with 39 RFA sessions. Ten lesions which developed LTP received a second round of RFA; four lesions received three rounds of treatment. The mean follow-up time was 22 months. Seventy-two PET/CT and 57 MR examinations were performed for follow-up. The accuracy and sensitivity for tumor detection was 86% and 76% for PET alone, 91% and 83% for PET/CT and 92% and 75% for MRI, respectively. Conclusions In comparison to PET alone, PET/CT was significantly better for detecting LTP after RFA. There were no significant differences between MRI and PET/CT. These preliminary results, however, need further verification.

Peripheral Mass–Forming Cholangiocarcinoma in Cirrhotic Liver

The purpose of this study was to determine whether particular enhancement patterns of intrahepatic cholangiocarcinoma in cirrhotic liver suggest the correct diagnosis. The CT findings on 28 lesions in 26 patients with underlying liver cirrhosis and pathologically proven cholangiocarcinoma were retrospectively evaluated. The CT findings of hepatocellular carcinoma (HCC) in a control group of 79 subjects also were analyzed. The relative attenuation and enhancement pattern of the lesions were evaluated by two observers in consensus. The difference between the enhancement pattern of cholangiocarcinoma and that of HCC was statistically analyzed with the Fisher's exact test. The prevalent enhancement patterns of cholangiocarcinoma on enhanced CT scans differed depending on tumor size. Peripheral rimlike enhancement was the most frequent (nine of 20 cases) pattern in tumors larger than 3 cm in diameter. A washout pattern on portal venous phase scans was the most frequent (five of eight cases) in tumors smaller than 3 cm in diameter. For tumors smaller than 3 cm in diameter, there was no significant difference between the enhancement pattern of cholangiocarcinoma and that of HCC. For tumors larger than 3 cm, the presence of peripheral rimlike enhancement or centripetal enhancement and the absence of a washout pattern were significant findings for differentiating cholangiocarcinoma from HCC (p < 0.0001). The contrast enhancement patterns of cholangiocarcinoma in cirrhotic liver on multiphasic helical CT scans were found to differ depending on tumor size. Because of the overlapping imaging findings in the two diseases, for any hypovascular lesion smaller than 3 cm in a cirrhotic liver, the diagnosis of cholangiocarcinoma should be seriously considered along with that of HCC.

Scirrhous hepatocellular carcinoma: Comparison with usual hepatocellular carcinoma based on CT–pathologic features and long-term results after curative resection

Objective To compare the CT and pathologic features and the long-term results of scirrhous hepatocellular carcinoma (HCC) after a curative resection with those of usual HCC. Methods Twenty-one patients with a scirrhous HCC and 296 patients with a usual HCC underwent contrast-enhanced triple-phase helical CT examinations before and after the curative resection. The CT and pathological features of scirrhous HCC, along with the cumulative survival and recurrence rates after the curative resection using a Kaplan–Meier method were compared with those of a usual HCC. Results The common CT features of scirrhous HCC were an ill-defined tumor margin (76%), peripheral rim-like enhancement on arterial and portal phases (62%), presence of area of prolonged and delayed enhancement on equilibrium phase (95%), and hepatic surface retraction (59%) and the uncommon CT features were presence of washout area (19%) and tumor capsule enhancement (5%), which were significantly different from those of usual HCC ( p < 0.05). Pathologically, the tumor capsule formation (29%) and tumor necrosis or hemorrhage (10%) were significantly less than those (81% and 43%, respectively) in usual HCC ( p < 0.05), while portal or hepatic vein involvement (33%) was significantly more common than in usual HCC (9%) ( p < 0.05). There were no statistically significant differences in the 5-year cumulative survival and recurrence rates between the two groups ( p > 0.05). Conclusion Scirrhous HCC showed distinct CT and pathologic features from those of usual HCC. After the curative resection, the long-term results of scirrhous and usual HCCs were not significantly different.

Morphologic and Functional Changes in Nontumorous Liver Tissue After Radiofrequency Ablation in an In Vivo Model: Comparison of 18F-FDG PET/CT, MRI, Ultrasound, and CT

Rimlike contrast enhancement on morphologic imaging and increased tracer uptake on (18)F-FDG PET in the periphery of the necrosis can hamper differentiation of residual tumor from regenerative tissue after radiofrequency ablation of liver lesions. This study used MRI, CT, ultrasound, and (18)F-FDG PET/CT to assess the typical appearance of lesions in nontumorous animal liver tissue after radiofrequency ablation. Lesions were created by radiofrequency ablation of normal liver parenchyma in 21 minipigs. Follow-up was performed by 3 contrast-enhanced morphologic modalities-MRI, CT, and ultrasound-and by (18)F-FDG PET/CT immediately, 3 and 10 d, and 1, 2, 3, and 6 mo after radiofrequency ablation. Images were evaluated qualitatively for areas of increased enhancement and regions of elevated tracer uptake. Furthermore, all images were assessed quantitatively by determination of ratios comparing enhancement/tracer uptake in the periphery of the necrosis with enhancement/tracer uptake in normal liver parenchyma. Imaging findings were compared with histopathology findings. Immediately after radiofrequency ablation, no increase in (18)F-FDG uptake was visible, whereas elevated enhancement was noticed in the periphery of the necrosis on all morphologic imaging procedures. At further follow-up, an area of rimlike increase in (18)F-FDG uptake surrounding the necrosis was detected on PET/CT. The rimlike pattern of increased enhancement in the arterial phase was present for all liver lesions on CT, MRI, and ultrasound, especially between day 3 and month 1 after the radiofrequency ablation. Both elevated glucose metabolism and enhancement persisted for 6 mo postinterventionally. Histologic examination showed a hemorrhagic border converting into a regeneration capsule. If performed immediately after radiofrequency ablation, (18)F-FDG PET/CT probably has benefits over those of morphologic imaging procedures when assessing liver tissue for residual tumor. Later follow-up may be hampered by visualization of peripheral hyperperfusion and tissue regeneration. Further studies on a patient population are essential.

Multiple biliary hamartomas: magnetic resonance features with histopathologic correlation

The purpose of this study was to report the magnetic resonance imaging (MRI) features of multiple biliary hamartoma (MBH) and to correlate them with histopathology. MRI features of 11 patients with MBH proven by histology were retrospectively reviewed and correlated to histopathology. MBH presented as multiple, tiny, and uniformly distributed lesions in all cases. All were hypointense on T1-weighted images and hyperintense on T2-weighted images relative to the liver parenchyma. Mural nodules were identified in 10 of 11 (91%) cases. They were isosignal on T1-weighted images, intermediate signal on T2-weighted images. Gadolinium-enhanced images showed mural nodule enhancement in 9 of 10 patients (90%) or a peripheral rim-like enhancement of the whole lesion in one case (9%). MBH were present in all liver specimens. In the six patients examined at MR cholangiography, the lesions lacked communication with the biliary tree. At histopathology, the mural nodule corresponded to an endocystic polypoid projection made of conjunctive septa. Three (27%) patients had associated focal nodular hyperplasia, and 1 (9%) had concomitant cholangiocarcinoma. MRI features allowed diagnosis of MBH with accuracy. Their recognition, especially the mural nodule, may help avoid misdiagnosis.

Commentary

To investigate pituitary abscess (PA) magnetic resonance imaging (MRI) features to improve the neuroradiologic and diagnostic knowledge of this rare disease and guide follow-up treatments.Clinical data were collected for 51 patients with PA, and MRI data were quantitatively reviewed in a retrospective analysis. Clinical factors were analyzed to investigate their relevance.PA neuroimaging showed special radiologic features, including hypointensity or isointensity on T1-weighted imaging (30 patients, 58.8%), isointensity or hyperintensity on T2-weighted imaging (39 patients, 76.5%), and disappearance of the posterior pituitary bright spot in most patients (44 patients, 86.3%). After gadolinium injection, rim or rimlike enhancement was observed in 82.4% of patients (n = 42). Half of those patients showed typical rim enhancement (profound peripheral enhancement with internal hypointensity); others showed atypical rim enhancement with special signs, such as enhanced, thick abscess wall and hyperintense flocculent or cottonlike foci within the internal hypointense region. Almost all patients (96.1%) presented at least 1 sign of adjacent anatomic structure invasion, including peripheral meninges enhancement, pituitary stalk thickening, and paranasal sinus mucosa enhancement. Rank correlation analysis of the clinical time course and MRI characteristics of PA showed a Spearman correlation coefficient of 0.270, indicating borderline significance (P = 0.055).Classic MRI characteristics of PA show T1 signal hypointensity or isointensity, T2 signal isointensity or hyperintensity, and peripheral rim enhancement after gadolinium injection. The MRI appearance of PA may reflect the abscess liquefaction and formation. Despite its profound significance for differential diagnosis, adjacent structure invasion is generally ignored by clinicians.

Intraductal papillary mucinous neoplasms of the pancreas: correlation of helical CT and dynamic MR imaging features with pathologic findings

We assessed the imaging features of intraductal papillary mucinous neoplasms (IPMNs) of the pancreas paying special attention to underlying pancreatic fibrosis on three-phase helical computed tomography (CT) and dynamic magnetic resonance (MR) imaging. Sixteen patients with histopathologically proven IPMNs underwent three-phase helical CT and dynamic MR imaging. IPMNs were seen as a cluster of cyst-like structures in branch duct (n = 5) and combined types (n = 10), and as a fusiform appearance in the main duct type (n = 1). IPMN shape was most easily visualized at the portal venous dominant phase or delayed phase owing to rim-like enhancement of the dilated ducts. Pathologically mild to severe fibrosis was seen on this enhanced rim replacing the surrounding pancreatic parenchyma. Communication between the dilated branch ducts and main pancreatic duct was identified in 15 patients on helical CT and 14 patients on dynamic MR imaging. In patients with fibrosis of pancreatic parenchyma surrounding this, communication was most easily visualized at the later phase on CT and MR imaging. Adenocarcinomas were depicted as papillary projections in eight of nine patients on CT and MR imaging. Invasion of the pancreatic parenchyma was seen in five of six patients as a solid mass in the pancreatic parenchyma. These masses were most easily visualized at the arterial dominant phase on both CT and MR imaging. Three-phase helical CT and dynamic MR imaging were useful in the diagnosis of IPMN of the pancreas.

Eosinophilic enteritis: CT features

We report CT features of four cases of Eosinophilic enteritis. The disease involves the jejunum in one case, the ileum in two cases, and the colon in the remaining case. Two cases demonstrate a predominantly mucosal type of eosinophilic enteritis, while the other two cases demonstrate a predominantly subserosal type. CT findings include bowel wall thickening in four cases, bowel fold thickening in two cases, layering of the bowel wall in two cases, luminal narrowing without obstruction in three cases, an intra-luminal granuloma mimicking a huge polyp in one case, an extra-luminal irregular granuloma markedly enhancing and slightly necrosing in one case, mesenteric lymphadenopathy with peripheral rim-like enhancement and marked necrosis in one case and ascites in one case. CT findings are more characteristic of an inflammatory disease rather than of a tumor, and these findings are helpful for assessing the extent and location of the disease. Moreover, combined with its typical clinical manifestations, CT findings may lead to the correct diagnosis.

Contrast‐enhanced ultrasound of histologically proven liver hemangiomas†

Differentiation of small and atypical hemangiomas from other hepatic masses using imaging methods can be difficult, especially in patients with underlying malignant disease. Therefore, contrast-enhanced ultrasound was assessed in patients with histologically confirmed hemangiomas with respect to contrast-enhancing kinetics and tumor characteristics. In 58 patients with indeterminate hepatic lesions demonstrated with at least 2 imaging methods (ultrasound/computed tomography/magnetic resonance imaging), ultrasound-guided liver biopsy revealed hemangioma. In all patients a hepatic neoplasm had been suspected because of underlying malignant disease (n=41), liver cirrhosis (n=15), or growth of the lesion (n=2). All patients underwent nonlinear, low mechanical index real-time contrast-enhanced ultrasound scanning with bolus injections of SonoVue. Peripheral nodular arterial enhancement was detected in 43 patients (74%), whereas the typical metastatic peripheral rim-like enhancement was not observed at all. Strong homogenous arterial enhancement was found in 9 of 58 (16%) patients. In 6 patients (10%), the arterial contrast enhancement pattern could not be determined because of the very small size of the lesions or fibrotic nodules. Forty-five (78%) of the hemangiomas showed homogenous centripetal filling within 180 seconds. Contrast-enhanced ultrasound demonstrates typical hemangioma imaging characteristics, that is, peripheral nodular contrast enhancement and iris-diaphragm sign in a high percentage of patients with undetermined lesions. This technique may therefore improve noninvasive functional characterization and differentiation of hemangiomas.