Chi-Jen Chen

CT features of genitourinary tuberculosis.

The genitourinary system is the most common site of extrapulmonary tuberculous infection. The diagnosis is difficult and often delayed. In this essay, we illustrate the CT features of the kidneys, ureters, bladder, prostate gland, and seminal vesicles caused by tuberculosis.

Intracranial meningeal melanocytoma: CT and MRI

Abstract We report the MRI and CT findings of an intracranial meningeal melanocytoma (IMM) arising from Meckels cave and review the imaging characteristics of IMM. On CT, IMM constantly appear as well-circumscribed, isodense to slightly dense, extra-axial tumours with homogeneous contrast enhancement. This appearance is nonspecific and similar to that of meningiomas or small neuromas. On MRI, the signal of IMM is strongly related to the amount of melanin pigment: the more melanin, the more shortening of T1 and T2 relaxation times. Only when it shows as a homogeneous mass, bright on T1 and dark on T2 weighting, can a specific diagnosis of a melanin-containing tumour be made. However, this still cannot provide a distinction between IMM and malignant meningeal melanoma.

Imaging spectrum of adrenal pseudocysts on CT.

Abstract. The aim of this study was to analyze the imaging spectrum of adrenal pseudocysts on CT. The CT images of seven patients with pathologic diagnosis of adrenal pseudocysts in our hospital were reviewed for the size, cystic part, solid part, septum, calcification, acute hematoma, and layering appearance. The presence or absence of contrast enhancement of solid parts in each lesion was also assessed if possible. Of the seven adrenal pseudocysts, there were three pure cystic, three mixed cystic and solid, and one solid lesions on CT. Two of the three cystic pseudocysts were septated with calcifications. Layering appearance was present in two mixed lesions. There were central calcifications and acute hematomas in one solid mass. In our study, there was no contrast enhancement of the solid parts of adrenal pseudocysts. The CT appearances of adrenal pseudocysts may range from cystic, mixed, to solid masses. The presence of solid parts of adrenal pseudocysts on CT mimics those of adrenal neoplasms; however, no contrast enhancement of the solid part in the lesion may help in the diagnosis of adrenal pseudocysts and their differentiation from adrenal neoplasms.

Balò's concentric sclerosis: MRI

We report a case of Balòs concentric sclerosis. In the past, the diagnosis was usually made post mortem. In this case, we found that CT demonstrated only low-density lesions, but not their concentric pattern. However, MRI showed a striking feature, reminiscent of histopathology of Balòs concentric sclerosis, and played an important role in antemortem diagnosis of this rare demyelinating disease.

Microcystic Meningioma : Importance of Obvious Hypointensity on T1-Weighted Magnetic Resonance Images

Purpose: To investigate the sensitivity and specificity of various magnetic resonance imaging findings for microcystic meningioma. Methods: Magnetic resonance images of 26 patients with microcystic meningioma (8 from our series and 18 from the literature) and 32 control subjects with other types of meningiomas were evaluated for obvious hypointensity relative to the cerebral cortex on T1-weighted images (T1WIs), obvious hyperintensity relative to the cerebral cortex on T2-weighted images (T2WIs), a radial or sunburst vascular pattern, marginal and reticular enhancement, severe peritumoral brain edema, and the dural tail sign. Differences in the frequencies of these findings between the microcystic and control groups were examined by means of the &khgr;2 test. The sensitivity, specificity, positive predictive value, and negative predictive value of these findings in the diagnosis of microcystic meningioma were calculated. Multivariate analysis of the findings was also performed. Results: The frequencies of obvious hypointensity on T1WI, obvious hyperintensity on T2WI, marginal and reticular enhancement, and severe peritumoral brain edema significantly differed between the microcystic and control groups (all P < 0.005). Sensitivities and specificities of hypointensity on T1WI and hyperintensity on T2WI in the diagnosis of microcystic meningioma were greater than 87%. After multivariate analysis, obvious hypointensity on T1WI was the only significant predictor of microcystic meningioma, with an odds ratio of 75.0 (95% confidence interval, 3.7-1536.0). Conclusion: Obvious hypointensity relative to the cerebral cortex on T1WI was the most valuable magnetic resonance finding in the diagnosis of microcystic meningioma.

Evolution of pontine and extrapontine myelinolysis: Clinical correlation with serial CT and MRI studies

Central pontine myelinolysis (CPM) and extrapontine myelinolysis (EPM) usually occur in patients with hyponatremia and rapid correction [1–3]. The clinical manifestations have included a subacute onset of conscious disturbance, quadriparesis and cerebellar signs. In earlier studies, CPM and EPM were diagnosed only at autopsy; recently, the diagnosis has frequently been made by CT or MRI [4–6]. Although these conditions are considered to be related with chro-nicity of hyponatremia or a rapid change of osmolarity, the pathogenesis of CPM and EPM still remains incompletely elucidated. We encountered a patient with both CPM and EPM, who had serial imaging studies before and after ‘rapid’ correction of hyponatremia.

Cervical carcinoma: MR imaging with integrated endorectal/phased-array coils: a pilot study

Abstract. The purpose of this study was to investigate the value of using MRI with integrated endorectal/phased-array coils for the staging and determination of the extent of cervical carcinoma. Twenty-two consecutive patients with biopsy-proven cervical carcinoma underwent MRI with integrated endorectal/phased-array coils before treatment. Magnetic resonance imaging was compared with clinical staging using surgical and pathological results as the gold standard. Eighteen of 22 patients underwent surgery. Seventeen of the 18 patients were correctly staged using an integrated endorectal/phased-array MRI with an overall staging accuracy of 94%. Fourteen of the 18 patients had a correct clinical staging with an overall staging accuracy of 78%. The overall accuracy of pelvic lymph node metastasis detection was 89% on MRI. These data showed that MRI using integrated endorectal/phased-array coils was more accurate than the clinical approach for the staging of cervical carcinoma. Magnetic resonance imaging using integrated endorectal/phased-array coils is a highly promising modality for detecting and staging cervical carcinomas.

Small cell carcinoma of the bladder mimicking a gynecological tumor

A 68-year-old woman presented elsewhere with gross hematuria 1 week in duration. Abdominal computerized tomography (CT) showed a large tumor of the pelvic cavity. With a tentative diagnosis of a gynecological tumor with bladder invasion, she was referred to us. Chest radiograph was normal. Magnetic resonance urography with a half-Fourier acquisition, single shot turbo spin-echo sequence revealed right hydronephrosis and a right hydroureter with obstruction at the level of the distal ureter (fig. 1). Pelvic magnetic resonance imaging (MRI) showed a large tumor involving the right posterior wall of the bladder, right perivesicular fat and right distal ureter. The tumor was low in signal intensity on T1 and T2-weighted images. It was enhanced heterogeneously after gadolinium administration (fig. 2). At surgery an ulcerated polypoid tumor arising from the right lateral wall of the bladder was found. The tumor extended to the right ureterovesical junction, right distal ureter and right perivesicular area. Radical cystectomy, right nephroureterectomy and iliac lymph node dissection were performed. Histological examination revealed features of small cell carcinoma, which was confirmed by immunohistochemical staining. Following surgery the patient underwent adjuvant chemotherapy. However, she was diagnosed with hepatic metastasis and local recurrence on abdominal CT 4 months later, and died 7 months postoperatively.

MRI/myelographic localization of fistulous tract in spinal dural arteriovenous malformations prior to arteriography.

Objective Our goal was to use currently available imaging methods to localize the fistulous tract of spinal dural arteriovenous malformations (SDAVMs) prior to arteriography. Materials and Methods Two middle-aged men showed MR findings indicative of a SDAVM. In the first patient coronal T2-weighted (T2W) imaging identified the engorged draining radiculospinal vein and traced it back to the intervertebral foramen site where the “nidus” was located. Then, axial T2W imaging was performed at the level of the involved intervertebral foramen. In the second patient MRI failed to demonstrate the nidus; myelography was carried out and showed the course of the abnormal intraspinal vein. Results Successful MR/myelographic demonstration of the nidus (Case 1) or the abnormal intraspinal vein (Case 2) simplified and abbreviated the later studies. Conclusion With MRI and/or myelography we were able to localize the site of the fistulous tract in the two cases of SDAVM prior to spinal arteriography.