Three cases of collagenous fibroma with rim enhancement on postcontrast T1-weighted images with fat suppression.

Collagenous fibroma, also known as desmoplastic fibroblastoma, is a benign fibrous soft tissue tumor showing gradual growth, commonly without aggressive local infiltration. Today, preoperative radiological diagnosis is important to avoid over-treatment and unnecessary extensive procedures, but is difficult because diagnostic imaging findings for collagenous fibroma have not been established. We report MR imaging findings of three collagenous fibromas in correlation with their histopathology. The characteristic rim enhancement on post-contrast T1-weighted images with fat suppression was present in all three cases, and we consider this to represent the difference in vascularity between the outer capsule-like fibrous tissue and the inside of the tumor.

Occult myofibroblastic sarcoma detected on FDG-PET performed for cancer screening.

We present a rare case of occult low-grade myofibroblastic sarcoma (LGMFS) detected by marked 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) uptake on positron emission tomography (PET). A 46-year-old woman presented with abnormal FDG uptake in her back when FDG-PET was performed for cancer screening. The maximum standard uptake values (SUVmax) were 9.8. Physical examination and laboratory investigations revealed no abnormalities. Magnetic resonance images demonstrated an ill-defined 2 x 3 cm mass in the multifidus muscle. Excisional biopsy led to a pathological diagnosis of LGMFS. Additional wide resection was performed for local control. No local recurrence or distant metastasis was observed 12 months after the initial operation. This is the first report describing FDG-PET findings of LGMFS, suggesting a discrepancy between histological grade and SUV intensity in this low-grade entity.

Measurement of articular cartilage volumes in the normal knee by magnetic resonance imaging: can cartilage volumes be estimated from physical characteristics?

In recent times several studies have been performed on magnetic resonance imaging (MRI) sequences for imaging cartilage. A fat-suppressed three-dimensional sequence is one such noteworthy example. More recent studies have reported that the total volume of cartilage in a knee joint can be elucidated using this sequence. Based on these studies, we hypothesized that the total volume of cartilage in the knee joint may reflect certain other physical characteristics. The purpose of the current study was to clarify the articular cartilage volumes of the patella and femur in the human knee joints of healthy adults using MRI and to analyze the correlation of these volumes with other physical characteristics. The material comprised 68 knees of 68 Japanese healthy volunteers, aged from their twenties to their forties (37 men and 31 women) who had no past history of joint disease or trauma in the legs. The knees were imaged by MRI with a fat-suppressed three-dimensional sequence, and the cartilage volumes were calculated by computer processing. The factors analyzed were age, body weight, height, leg length, foot size, circumferences of the thigh and lower leg, the distance between medial and lateral femoral condyles, the diameter of the tibial head, body mass index, general joint laxity, quadriceps angle, and leg-heel alignment. The mean cartilage volume was 7.6 +/- 1.6 cm(3) (8.3 +/- 1.6 cm(3) in men, 6.7 +/- 0.9 cm(3) in women). It was significantly larger in men than in women. However, the volume positively correlated with body weight, height, leg length, and foot size, without distinction of gender or age. Based on these data, a multiple regression analysis was developed: cartilage volume = 0.113 x height - 11.053. We concluded that the cartilage volume depends on physical size regardless of gender, and it can be estimated from factors of physical size.

Usefulness of MR imaging in assessment of tumor extent of aggressive fibromatosis.

PURPOSE: We evaluated the usefulness of MR imaging for aggressive fibromatoses in order to determine tumor extent. MATERIALS AND METHODS: 17 lesions of 16 patients were examined with a 1.5-Tesla MR unit with unenhanced and gadolinium-enhanced T1WI, and T2WI. We retrospectively reviewed the MR features. RESULTS: The tumor had a smooth margin in 41% of cases, while an irregular margin was present in 59%. A low signal intensity band (LSB) followed a normal muscle tendon or fascia. LSBs were seen in all of the lesions with an irregular margin, but not in those with a smooth margin. LSB resembled thickened or uneven tendons. Five of the seven lesions with LSB had a positive surgical margin at the LSB on pathological feature, and they recurred. CONCLUSION: Detection of LSBs on MR images is important for the determination of tumor extent, which allows the surgical method to be decided and postoperative recurrence predicted.

Benign pleomorphic adenoma with extensive cystic degeneration: unusual MR findings in two cases.

Two cases of benign pleomorphic adenoma (PA) with extensive cystic degeneration are described. In both cases magnetic resonance (MR) imaging revealed entirely cystic tumors with an irregularity at the cyst wall. Some additional findings were observed: one case showed layering within the cyst contents caused by intratumoral hemorrhage, and the other had a small mural nodule at the cyst wall that showed very low intensity on both T1- and T2-weighted images and corresponded pathologically to the hyaline stroma. In both cases, preoperative diagnosis was difficult based on the MR findings alone. Benign PA should be included in the differential diagnosis of an entirely cystic parotid mass.

CT and MR findings of basal cell adenoma of the parotid gland.

We report a case of basal cell adenoma in the left parotid gland. A 34-year-old woman presented with a non-tender mass in the left parotid gland. She had first noted it 7- years previously, and it had been gradually increasing in size. The tumor was well-circumscribed with a smooth contour. On noncontrast-enhanced CT, the tumor showed homogeneous soft tissue attenuation. No cystic portion or calcification was seen. The tumor showed homogeneous moderate enhancement on contrast-enhanced CT. Capsule-like ring enhancement was demonstrated. On T1-weighted MR imaging, the tumor was homogeneously hypointense to the surrounding parotid tissue and isointense to muscle. On T2-weighted imaging the tumor was homogeneously hyperintense to muscle but slightly hypointense to the surrounding parotid tissue. On Gd-enhanced T1-weighted imaging, the tumor demonstrated homogeneous moderate enhancement. Capsule-like ring enhancement was also demonstrated. Salivary (technetium-99m-pertechnetate) scintigraphy did not show any uptake in the tumor.

Brown tumor of the sphenoid sinus in a patient with secondary hyperparathyroidism: CT and MR imaging findings.

We present a case of brown tumor of the sphenoid sinus in a patient with secondary hyperparathyroidism. CT showed an expansile soft-tissue attenuation mass centered in the sphenoid sinus. CT at bone window setting demonstrated expansile, lytic change and remodeling of the surrounding bone. On MR imaging, the lesion showed iso-intensity to gray matter on T1-weighted images and heterogeneous hyperintensity on T2-weighted images, and showed intense enhancement. The extent of the lesion and its relationship to the surrounding structures were best evaluated by CT and MR imaging.

Myolipoma of the retroperitoneum.

A case of retroperitoneal myolipoma is reported. A 55-year-old woman with the main complaint of an abdominal mass was admitted to Teikyo University Hospital, Tokyo, Japan. Retroperitoneal liposarcoma was suspected based on magnetic resonance imaging, and the tumor was resected. The resected tumor was well encapsulated and 30 x 15 x 8 cm in size. Histologically, it consisted of mature adipose cells and smooth muscle cells. Neither nuclear atypia nor mitosis was observed in either component. The tumor was pathologically diagnosed as myolipoma of the retroperitoneum. Retroperitoneal myolipoma is often misdiagnosed radiologically as liposarcoma because the overwhelming majority of large retroperitoneal tumor containing fat is liposarcoma, however, the clinical course of myolipoma is quite different from that of liposarcoma. Although myolipoma is very rare, pathologists should consider it in the differential diagnosis of fat-containing retroperitoneal masses.

Parachordoma with multiple metastases.

We present a very rare case of parachordoma with local aggressiveness and widespread metastases. A 68-year-old male presented with a mass in his left calf. The lesion was depicted as a poorly marginated mass with inhomogeneous signal intensity on magnetic resonance imaging. The tumor invaded surrounding muscles, neurovascular bundles, and bones. Widespread metastasis to lung, bone, and skin developed after amputation surgery. The histologic features of primary and metastatic lesions were the same and consistent with parachordoma.

Optimum iodine concentration of contrast material through microcatheters: hydrodynamic analysis of experimental results.

It is important to increase the iodine delivery rate (I), that is the iodine concentration of the contrast material (C) x the flow rate of the contrast material (Q), through a catheter to obtain high quality arteriograms. The iodine delivery rate varies depending on the iodine concentration of the contrast material. The purpose of this study is to estimate the optimum iodine concentration (Copt) of contrast material (i.e. the iodine concentration at which I becomes maximum) through a microcatheter of a given length (L), inner diameter (D) and injection pressure (P). Iohexol, ioversol and iopamidol of 11-12 iodine concentrations (140-350, 160-350 or 160-370 mg cm(-3)) at 37 degrees C are used. I and Reynolds number (Re) of the flow of each contrast material through four microcatheters (0.49-0.68 mm in inner diameter, 1000-1500 mm in length) at injection pressures of 1.38, 2.76, 4.14 and 5.52 x 10(6) Pa (200, 400, 600 and 800 pounds per square inch) are obtained experimentally. The relationships between I and C and between I and Re are examined for each catheter and injection pressure. Copt is 160-280 mg cm(-3) for iohexol, 180-280 mg cm(-3) for ioversol and 200-300 mg cm(-3) for iopamidol. I becomes maximum when Re approximates the critical Reynolds number (Re approximately 2300). Utilizing this principle, we can estimate Copt and its flow rate through a microcatheter of a given L, D and P.

[A case of adenomyosis showing multiple large cysts on MR imaging].

Adenomyosis is a condition characterized by benign invasion of the endometrium into the myometrium associated with reactive hypertrophy of the surrounding musculature. The ectopic endometrium in adenomyosis is of the basalis type, and menstrual bleeding is less common than in endometriosis. We report a rare case of adenomyosis that had multiple, large, adenomyotic cysts. These cysts were located in the outer layer of adenomyosis on MR imaging. Pathologic features consisted of blood-filled cysts of 1 cm to 5 cm in maximum diameter of the functioning endometrial type.

Effect of superparamagnetic iron oxide-enhanced MRI of the liver with hepatocellular carcinoma and hyperplastic nodule.

PURPOSE: To evaluate the possibility of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) of the liver in predicting the histologic grade of hepatocellular carcinoma (HCC) and differentiating HCC from benign hyperplastic nodule (HPN). MATERIALS AND METHODS: Thirty patients with 31 histologically proved HCC and HPN underwent MRI (1.5 Tesla). HCCs were graded into well-differentiated HCC (HCCw; n = 10) and moderately to poorly differentiated HCC (HCCmp; n = 15). HPN was categorized into dysplastic nodule (DN; n = 1) and focal nodular hyperplasia (FNH; n = 6). T2-weighted fast spin echo images were obtained before and after administration of SPIO. Signal-to-noise ratios (SNR) of the lesion and surrounding liver parenchyma and contrast-to-noise ratios (CNR) were calculated pre- and postcontrast study. Relative enhancement ratios (RER), also known as signal intensity reduction ratios of the lesions, were also calculated. RESULTS: HCCw, HCCmp, DN, and FNH decreased in SNR after injection of SPIO. RER of HCCw was 19.5 +/- 13.3%, that of HCCmp was 6.8 +/- 5.8%, DN was 44.0%, and FNH was 42.9 +/- 4.8%. Significant statistical differences were seen between HCCw and HCCmp and HCC and HPN in RER. HCCw, HCCmp, and DN increased in CNR, and FNH decreased in CNR, but no lesion showed a statistically significant difference in CNR. CONCLUSION: SPIO-enhanced MR images may help to predict the histologic grade of HCC and distinguish HCC from HPN.