Hidetoshi Miyake

CT and MR imaging of desmoplastic fibroblastoma

Abstract. Desmoplastic fibroblastoma (collagenous fibroma) developing as a slowly enlarging lower abdominal mass is described. The lesion had inhomogeneous low signal intensity (SI) on T1-weighted images, and mixed SI as low SI within high SI on T2-weighted images. On post-contrast T1-weighted images, the mass showed inhomogeneous enhancement. Histologically, the areas showing low SI on both post-contrast T1- and T2-weighted images consisted of dense collagenous components and reduced cellularity compared with the areas showing high SI on them.

MRI signal characteristics of progressive massive fibrosis in silicosis

AIM To determine the magnetic resonance imaging (MRI) signal characteristics of progressive massive fibrosis (PMF) in silicosis. SUBJECTS AND METHODS We evaluated prospectively the MR appearances in 17 patients with 34 PMF lesions on the basis of pre-contrast signal intensity (SI) and SI pattern and post-contrast enhancement pattern, using a 0.5-T unit. There were 13 PMF lesions in six patients who had silicosis and 21 PMF lesions in 11 patients who had silicotuberculosis. The SI pattern on T2-weighted image (WI) was classified into four types and the pattern of contrast enhancement on T1-WI was classified into three types. MR appearances of PMF lesions were correlated with the findings of computed tomography (CT). RESULTS The commonest signal intensity characteristic was isointensity (70%) on T1-WI and hypointensity (68%) on T2-WI when compared with skeletal muscle. For signal pattern on T2-WI, a type with only internal high SI areas (46% in silicosis group, 38% in silicotuberculosis group) was most frequent. All of these areas corresponded to the low density areas at CT, suggestive of necrosis. After intravenous contrast medium enhancement, rim enhancement (54% in silicosis group, 52% in silicotuberculosis group) was most frequent, followed by no enhancement. CONCLUSION The most common MRI appearance of PMF was isointensity on T1-WI and hypointensity on T2-WI when compared with skeletal muscle, with internal high SI areas on T2-WI and either rim enhancement or no enhancement.

Mediastinal lymphangiomas in adults : CT findings

Mediastinal lymphangioma is rare in adults, and there are few reports of their computed tomographic (CT) findings. We present the CT results in three cases of mediastinal lymphangioma. One showed a well-defined, multilocular, water-density mass enveloping mediastinal structures, without their displacement or compression; one presented as a well-defined, homogeneous, water-density mass in the right paratracheal region; and one was associated with hemorrhage into cysts and a significant increase in size over 5 years. CT is useful for diagnosis and evaluation of the extent or contents of mediastinal lymphangiomas.

Diagnosis of lung cancer in a patient with pneumoconiosis and progressive massive fibrosis using MRI

Abstract. We report the MRI features and correlative pathologic findings of a lung cancer in a patient with progressive massive fibrosis (PMF). In this case, MRI was able to distinguish the lung cancer as a high signal intensity area, and the fibrotic mass as a low signal intensity area, on both T1-weighted and T2-weighted images when compared with muscle. MRI is potentially useful in distinguishing cancer tissue from PMF in patients with pneumoconiosis.

Adrenal nonhyperfunctioning adenoma and nonadenoma: CT attenuation value as discriminative index.

BackgroundWhen an asymptomatic adrenal mass is incidentally discovered on abdominal CT scans, the distinction between a nonhyperfunctioning adenoma and a nonadenoma would be important.MethodsWe evaluated the CT findings of 36 adrenal masses (14 nonhyperfunctioning adenomas, 22 nonadenomas) in 34 patients with no evidence of hormonal hypersecretion. CT attenuation values of adrenal masses on CT scans were calculated by setting a circular region of interest as large as possible in the center of each adrenal mass.ResultsBelow 20 HU in CT attenuation values, all adrenal masses, except one case of ganglioneuroma with myxomatous change, were nonhyperfunctioning adenomas. With an arbitrary threshold of 20 HU, the sensitivity of CT attenuation values in distinguishing nonhyperfunctioning adenomas from nonadenomas was 64%, the specificity was 95%, and the accuracy was 83%. When decreasing the threshold to 15 HU, the sensitivity was 64%, the specificity was 100%, and the accuracy was 86%. The CT attenuation value on noncontrast CT was more useful for making this distinction than the size and interior homogeneity.ConclusionsOur data suggest that an asymptomatic adrenal mass with homogeneous low attenuation (≦15 HU) and less than or equal to 4 cm indicates a nonhyperfunctioning adenoma, and no further examinations are necessary. CT attenuation value on non-contrast CT is the most important discriminatory factor.

Mucin-producing carcinoma of the gallbladder: Imaging demonstration in four cases

We report four cases of mucin-producing carcinoma of the gallbladder (three papillary adenocarcinomas and one mucinous carcinoma), with an emphasis on imaging features. Our findings suggest that when a papillary protrusion or thickened wall, including cystic areas and/or calcifications, is seen radiologically in the enlarged gallbladder, mucin-producing carcinoma of the gallbladder should be included in the differential diagnosis.

Mucin-producing Tumor of the Lung: Ct Findings

Primary lung tumors and pulmonary metastases with a large mucin content are relatively rare, and reports of CT findings are scarce. We present the CT images of patients with mucinous bronchioloalveolar carcinoma and lung metastasis of mucinous adenocarcinoma of the colon. The CT findings include a uniform low attenuation (4.5 and 7.8 HU), irregular margins, and slight enhancement after intravenous injection of contrast medium.

MRI of Cervical Masses of Thymic Origin

Objective Thymic diseases can arise from remnants of thymic tissues along the path of fetal descent and may simulate thyroid tumors or lymphadenopathy. Materials and Methods We present two patients with a cervical mass arising from the cervical thymus that was caused by incomplete descent of the thymus into the mediastinum. Results In one patient a cervical mass was surgically confirmed to be a cervical thymoma, which simulated a thyroid cancer on CT and 201Tl-scintigraphy. In another patient, cervical thymic hyperplasia arising from an incompletely descended thymus was surgically confirmed. The isointensity between the cervical mass and an enlarged mediastinal thymus was recognized on MRI. Conclusion If a cervical mass is located in the region of the lower pole of the thyroid or if there is a connection or the same intensity between the cervical mass and the mediastinal thymus on MRI, a diagnosis of a cervical mass of thymic origin should be considered.

Computed tomography in amyloid goiter.

Two cases of amyloid goiter showed diffuse decreased density of enlarged thyroid on CT. The diffuse decreased density of amyloid goiter on CT is thought to represent large amount of adipose tissue often found in amyloid goiter. When diffuse decreased density of the enlarged thyroid is recognized on CT, amyloid goiter should enter into differential diagnosis.

Lymphangiosis carcinomatosa of the liver deriving from gastric carcinoma with a unique branching calcification.

Accepted: 1 December 2003 Published online: 22 January 2004