Voxel-based Histographic Analysis of the Basilar Artery in Patients with Isolated Pontine Infarction.

BACKGROUND AND PURPOSE: The signal information per voxels of magnetic resonance imaging (MRI) for vessel wall could reflect the pathologic features of atherosclerotic vessels. The aim of this study is to evaluate the usefulness of magnetic resonance voxel-based histogram (VBH) of atherosclerotic basilar artery in patients with isolated pontine infarctions (PIs). MATERIALS AND METHODS: Wall and lumen of basilar artery were segmented from high resolution MR of 42 patients with isolated PI and 10 normal volunteers. VBHs were obtained after normalization by dividing the intensity of segmented wall with the intensity of non-infarcted area of pons. The variables of VBH included area (A), mean signal intensity (SI), standard deviation (SD), kurtosis (K), and skewness (SK) and area stenosis [AS; Awall/(Awall + Alumen)] were compared according to the MRI-modified American Heart Association (AHA) atherosclerotic plaque schema, and between the subgroups of PI (lacunar: LPI and paramedian: PPI). RESULTS: According to the MRI-modified AHA atherosclerotic plaque schema, Awall/T1 (mean area of wall on T1-weighted MRI), SIwall/T1, SDwall/T1, SKwall/T1, Kwall/T1, Alumen/T1, and AST1 showed statistical differences. AHA IV-VII showed higher Awall/T1, SIwall/T1, and AST1 than normal control. PPI showed statistical differences in Awall/T1, SIwall/T1, SK wall/T1, and Awall/T2 than those of normal control after post hoc test, whereas LPI in Awall/T1 and Awall/T2 (P < 0.05, Kruskal-Wallis test, Dunnett T3 procedure). CONCLUSIONS: VBH analysis can provide the quantitative information with regard to volume as well as composition of the atherosclerotic plaque in the basilar artery. The difference in patterns of VBH might be further useful in characterizing PIs with presumably different pathogenesis.

Imaging finding of malignant melanoma of Eustachian tube with extension to middle ear cavity: case report.

We report a case of malignant melanoma of Eustachian tube with extension to the middle ear cavity and nasopharynx in a 51-year-old woman who presented with right ear fullness. Computed tomography showed a soft tissue mass in the middle ear cavity and caused the widening and eroding of the bony eustachian tube. Magnetic resonance imaging showed well enhancing mass in eustachian tube extending nasopharynx to middle ear cavity. A biopsy of the middle ear cavity mass revealed a malignant amelanotic melanoma.

Three-dimensional magnetic resonance rendering imaging of lumbosacral radiculography in the diagnosis of symptomatic extraforaminal disc herniation with or without foraminal extension.

STUDY DESIGN: Retrospective analysis of lumbosacral radiculography using 3-dimensional (3D) magnetic resonance (MR) rendering in patients with extraforaminal disc herniation. OBJECTIVE: To investigate the significance of lumbosacral radiculography as depicted by 3D MR rendering in the diagnosis of symptomatic extraforaminal disc herniation with or without foraminal extension. SUMMARY OF BACKGROUND DATA: Given that accurate evaluation of the extraforaminal zones on routine axial and sagittal images is difficult, extraforaminal disc herniations tend to be sometimes overlooked. In addition, oblique coronal images along intervertebral foramina and MR myelography may not clearly demonstrate a detailed full view of nerve root changes. Furthermore, the detection of the morphologic changes of the nerve root is very important for the diagnosis of symptomatic extraforaminal disc herniation. Thus, a useful method for evaluating the nerve root in order to diagnose symptomatic extraforaminal disc herniation is required. METHODS: Twenty-four patients with extraforaminal and combined (extraforaminal with foraminal) lumbar disc herniations were included in this study. Conventional spin-echo sequence and 3D coronal fast-field echo sequences with selective water excitation by using the principles of the selective excitation technique (Proset imaging) were acquired. Indentation and swelling of the nerve roots and dorsal root ganglion (DRG) in the symptomatic sides and levels were evaluated on the basis of 3D MR rendering images of the lumbar spine. The tilting angle of the nerve root in the symptomatic side was compared with those in the asymptomatic contralateral side again on the basis of the 3D MR rendering images. RESULTS: Dorsal root ganglion indentation without swelling of the nerve roots was found in 7 patients whereas that with swelling of the nerve roots was observed in 6 patients. Swelling of the entire segment of the nerve from nerve root to spinal nerve (n = 9) or only the spinal nerve (n = 2) was observed in 11 patients. Compared with the contralateral nerve root, 7 patients exhibited a tilting angle abnormality of the ipsilateral nerve root. CONCLUSION: Based on lumbosacral radiculography through 3D MR rendering, important findings related to the diagnosis of symptomatic extraforaminal disc herniation include swelling of DRG and/or nerve roots and DRG indentation. Ultimately, 3D MR lumbosacral radiculography is a very useful method in the diagnosis of the symptomatic extraforaminal disc herniation.

Posterior reversible leukoencephalopathy due to "triple H" therapy.

Posterior leukoencephalopathy syndrome is a rare complication of triple H therapy, which is the treatment for symptomatic vasospasm occurring following subarachnoid hemorrhage. This complication must be considered when neurological deterioration of a patient continues or worsens during triple H therapy. We report a patient diagnosed with posterior leukoencephalopathy syndrome during triple H therapy.

A proposal for a thyroid imaging reporting and data system for ultrasound features of thyroid carcinoma.

BACKGROUND: Several thyroid ultrasound (TUS) findings have been associated with an increased risk for thyroid cancer; however, there is no consensus as to the format and style for reporting the results of TUS. The objective of this study was to discover the features indicative of malignancy in thyroid nodules based on TUS, generate an equation using these features that would be predictive of malignancy in thyroid nodules, and stratify the results of this equation into TUS categories reflecting the probability of malignancy. METHODS: We obtained odds ratios of TUS findings indicative of malignancy and probability of malignancy for each nodule as determined by logistic regression analysis of ultrasound (US) findings in 1694 patients who had US-guided fine-needle aspiration biopsy. We then generated an equation to predict the probability of malignancy based on TUS and developed categories ranging from lowest to highest probability of malignancy. We evaluated the reliability of this equation and the categories using cytology and histopathology information regarding malignancy in the thyroid nodules. RESULTS: We characterized 12 aspects of thyroid nodules as seen on TUS and developed an equation to predict P(us), the probability of a nodule being malignant based on these US findings. The equation was P(us) = 1/(1 + e(-z)), where e is the mathematical constant 2.71828 and z is the logit of malignant thyroid nodule. P(us) was stratified into five categories based on the probability of a nodule being malignant as indicated by the findings (TUS 1, benign; TUS 2, probably benign; TUS 3, indeterminate; TUS 4, probably malignant; TUS 5, malignant). There was a significant correlation between the cytological category and the TUS 1 through TUS 5 categories (r = 0.491, p < 0.001). CONCLUSIONS: We propose an equation to predict the probability of malignancy in thyroid nodules based on 12 features of thyroid nodules as noted on TUS. This equation, and the stratification of its results into categories, should be useful in reporting the findings of US for thyroid nodules and in guiding management decisions.

Aberrant pyramidal tract in medial lemniscus of brainstem in the human brain.

The aberrant pyramidal tract (APT) refers to the collateral pathway of the pyramidal tract through the medial lemniscus in the brainstem. We showed the presence of an APT in the normal human brain using diffusion tensor tractography. Diffusion tensor tractography showed that the motor tracts of the 28 hemispheres in 14 healthy normal individuals originated from the primary sensori-motor cortex and descended through the known pathway of the pyramidal tract. However, in five (17.9%) of the 28 hemispheres, we observed that the APT descended through the medial lemniscus from the midbrain to the pons, and then entered into the pyramidal tract at the upper medulla, after which it descended through the pyramidal tract to the lower medulla.

Pattern approach to MR imaging in patients with end-stage hepatic failure: a proposal for a new disease entity "hepatic encephalopathy continuum".

INTRODUCTION: The purpose of this study was to evaluate the clinical features and the characteristics of MR images of patients with end-stage hepatic failure. METHODS: We reviewed the MR findings and clinical features of 31 consecutive patients (20 men, 11 women=31, mean age 58.7 years) who had been diagnosed with clinical hepatic encephalopathy. Associations between the lesion locations on each MR sequence were analyzed using a binominal test. The clinical and MR findings were compared in relation to the etiology and clinical status. RESULTS: The most frequently involved site, seen as high signal intensity on T2-W images, was the corpus callosum (20 patients), followed by the dentate nucleus (16 patients) and the globus pallidus (13 patients). Significant associations were seen between the pallidus and the crus cerebri, between the crus cerebri and the red nucleus, between the crus cerebri and the dentate nucleus, and between the red nucleus and the dentate nucleus on the T2-W and DW images (P < 0.004). The crus cerebri, red nucleus, and dentate nucleus were involved concurrently with the corpus callosum more frequently in hepatic encephalopathy grades 3 and 4. CONCLUSION: Concurrent involvement of the globus pallidus-crus cerebri-red nucleus-dentate nucleus axis was the main MR pattern in end-stage hepatic encephalopathy, which connected with various areas of the brain. We hypothesize that these overlapping MR features could be regarded as an entity denoted as the "hepatic encephalopathy continuum".

Diffusion-weighted magnetic resonance imaging of sacral insufficiency fractures: comparison with metastases of the sacrum.

STUDY DESIGN: Retrospective analysis of magnetic resonance imaging (MRI) for differentiating sacral insufficiency fractures from metastases of the sacrum. OBJECTIVE: To determine if a steady-state free precession (SSFP) diffusion-weighted MRI is useful for differentiating sacral insufficiency fractures from metastases of the sacrum. SUMMARY OF BACKGROUND DATA: Conventional spin-echo sequence MRI is very sensitive for the detection of pathologic lesions in the sacrum, but the differential findings between sacral insufficiency fracture and metastasis are often not obvious because of the nonspecific changes of signal intensity. Another MR sequences for differentiation is needed. METHODS: Fourteen patients with sacral insufficiency fractures and 8 patients with metastasis at the sacrum were examined with MRI. Both the diffusion-weighted MRI and the spin-echo MRI were performed in all patients. Diffusion-weighted MRI sequences were based on a SSFP sequence. RESULTS: All the insufficiency fractures and metastasis at the sacrum revealed low signal intensity on T1-weighted MRI; low or high signal intensity was revealed on T2-weighted MRI. The contrast enhanced T1-weighted MRI showed strong enhancement at the sacrum in all cases of insufficiency fracture and metastasis. Diffusion-weighted MRI of the sacrum showed low signal intensity in all cases with sacral insufficiency fracture, but these images revealed high signal intensity in all cases with metastasis. CONCLUSION: SSFP diffusion-weighted MRI is capable of differentiating benign sacral insufficiency fractures from metastatic tumors of the sacrum.

[Undifferentiated carcinoma with osteoclast-like giant cells of the pancreas].

Undifferentiated carcinoma with osteoclast-like giant cells is a rare neoplasm of exocrine pancreas. Till recently, some cases have been reported, however histogenesis of the tumors are controversial and their characteristic findings have not been described yet. Thirty five-year-old men and 75-year-old men were presented with upper abdominal pain and a palpable mass. On computed tomography, one case showed a well enhancing solid tumor with low density and the other was showed a mainly cystic tumor with peripheral enhancement in the body and tail of the pancreas. One case accompanied multiple metastatic liver masses with subhepatic lymph node enlargement. Tumor staining was seen on angiography. Biopsy and pancreatectomy were performed. Pathological findings revealed tumors composed of neoplastic spindle shaped or pleomorphic large cells with scattered non-neoplastic osteoclast-like giant cells. In one case, there were small foci of adenocarcinoma components in the periphery of the tumor. On immunohistochemical stain, neoplastic cells showed focal positivity for epithelial membrane antigen and vimentin. Tumors were diagnosed as undifferentiated carcinoma with osteoclast-like giant cells. We report these rare cases with a review of literature.

Ultrasonographic Findings of Prepubertal Testicular Teratoma

PURPOSE: To evaluate the ultrasonographic findings of testicular teratoma arising in pre-pubertal children. MATERIALS AND METHODS: We studied 6 cases in 5 patients with pathologically proven testicular teratoma. Ultrasonography was performed in all cases and MRI in 5 cases. The location, size, shape, margin and internal echo pattern of the lesion were evaluated on ultrasonography and the shape, signal intensity and presence or absence of contrast enhancement were evaluated on MRI. RESULTS: The shape of all cases was round or oval and the lesion size ranged from 0.5 to 3.5 cm (average, 1.7 cm). Four of 6 cases were seen as cystic lesions, Three of which were multilocular and one was unilocular. The cystic lesions were filled with echo-free fluid without any solid component. The inner wall and septa were minutely granulated. One of 6 cases was seen as a predominantly cystic lesion containing heterogeneous, high echoic portions. One case was seen as a heterogeneous mixed echoic lesion with dirty posterior sonic shadowing. Three of the 4 cases seen as a cyst on ultrasonography were also seen as a cyst on MRI. In one case seen as a predominantly cystic lesion on ultrasonography, the periphery of the lesion was hypointense and the center was hyperintense on T2-weighted image. The remaining case seen as a heterogeneous mixed echoic mass was markedly heterogeneous in signal intensity both on T2- and T1-weighted images and hyperintense fat components were noted. Contrast enhancement was not seen in any of the 4 cases. CONCLUSION: On ultrasonography, pre-pubertal testicular teratoma is commonly seen as a multilocular or unilocular cyst and a minutely granulated appearance is noted in the inner wall or septa of the cystic lesion.

Non-infectious ischiogluteal bursitis: MRI findings.

OBJECTIVE: We wished to report on the MRI findings of non-infectious ischiogluteal bursitis. MATERIALS AND METHODS: The MRI findings of 17 confirmed cases of non-infectious ischiogluteal bursitis were analyzed: four out of the 17 cases were confirmed with surgery, and the remaining 13 cases were confirmed with MRI plus the clinical data. RESULTS: The enlarged bursae were located deep to the gluteus muscles and postero-inferior to the ischial tuberosity. The superior ends of the bursal sacs abutted to the infero-medial aspect of the ischial tuberosity. The signal intensity within the enlarged bursa on T1-weighted image (WI) was hypo-intense in three cases (3/17, 17.6%), iso-intense in 10 cases (10/17, 58.9%), and hyper-intense in four cases (4/17, 23.5%) in comparison to that of surrounding muscles. The bursal sac appeared homogeneous in 13 patients (13/17, 76.5%) and heterogeneous in the remaining four patients (4/17, 23.5%) on T1-WI. On T2-WI, the bursa was hyper-intense in all cases (17/17, 100%); it was heterogeneous in 10 cases and homogeneous in seven cases. The heterogeneity was variable depending on the degree of the blood-fluid levels and the septae within the bursae. With contrast enhancement, the inner wall of the bursae was smooth (5/17 cases), and irregular (12/17 cases) because of the synovial proliferation and septation. CONCLUSION: Ischiogluteal bursitis can be diagnosed with MRI by its characteristic location and cystic appearance.