Deep soft tissue leiomyoma of the thigh

A case of ossified leiomyoma of the deep soft tissues of the left thigh is presented. The radiographic appearance suggested a low-grade chondrosarcoma. MRI of the lesion showed signal characteristics similar to muscle on both T1- and T2-weighted spin echo sequences with linear areas of high signal intensity on T1-weighted images consistent with medullary fat in metaplastic bone. Histopathological examination of the resected specimen revealed a benign ossified soft tissue leiomyoma. Received: 23 December 1998 Revision requested: 31 January 1999 Revision received: 11 March 1999 Accepted: 16 March 1999     

Intramuscular metastasis from malignant melanoma: MR findings

We present a rare case of intramuscular metastasis from malignant melanoma. The lesion showed intermediate to high signal intensity on T1-weighted magnetic resonance (MR) images and mixed signal intensities containing high and low signals on T2-weighted images. The signal intensity on T1-weighted images, which is due to the paramagnetic effect of melanin, is a characteristic MR finding of this entity. Received: 10 June 1999 Revision requested: 7 July 1999 Revision received: 9 August 1999 Accepted: 9 August 1999     

Angiosarcoma associated with chronic lymphedema (Stewart-Treves syndrome) of the leg: MR imaging

Magnetic resonance (MR) imaging findings of two patients with Stewart-Treves syndrome are presented. MR imaging showed edematous changes in the subcutaneous fat and skin masses that proved to be angiosarcomas. MR signal intensity of the tumor was low compared with fat on T1-weighted images and intermediate and heterogeneous on T2-weighted images. In one patient, administration of intravenous Gd-DTPA showed marked enhancement in the early phase, which persisted until the delayed phase. These finding on dynamic MR imaging may reflect the abundant vascular spaces seen in these tumors. Received: 20 August 1999 Revision requested: 28 October 2000 Revision received: 31 January 2000 Accepted: 8 February 2000     

Hemangioma of bone arising in the ulna: imaging findings with emphasis on MR

An 18-year-old woman presented with left elbow joint pain. Radiographs and computed tomographic scan showed a well-defined osteolytic lesion of the left ulna associated with a honeycomb appearance on the radiographs. Magnetic resonance images showed intermediate signal intensity on T1-weighted images and mixed intermediate and high signal intensities on T2-weighted images. Only the periphery of the lesion enhanced with intravenously injected gadolinium-diethylenetriamine pentaacetic acid. The lesion was curetted to avoid pathologic fracture, and a histologic diagnosis of cavernous hemangioma of bone was made. Hemangioma involving the ulna is rare, but should be included in the differential diagnosis of a radiographic osteolytic lesion with a honeycomb appearance. Received: 17 September 1999 Revision requested: 31 October 1999 Revision received: 10 December 1999 Accepted: 13 December 1999     

Soft tissue perineurioma of the foot with 10q24 rearrangements: unique MRI features with histopathologic correlation

Perineurioma is an uncommon benign peripheral nerve sheath tumor with advanced perineurial differentiation. Two distinct subtypes are recognized: intraneural and soft tissue. We herein present a unique case of soft tissue perineurioma in the right foot of a 43-year-old man. Radiographs showed a non-specific soft tissue mass. On computed tomography scan, the mass was iso- to slightly hypodense relative to muscle. On T1- and T2-weighted images, the mass exhibited iso- to slightly low signal intensity relative to muscle with foci of high signal intensity. Slight contrast enhancement was noted on enhanced T1-weighted images with fat suppression. A marginal excision of the tumor was performed and histopathologic examination confirmed the diagnosis of soft tissue perineurioma. The clinicopathologic, radiologic, and cytogenetic findings are described, and the relevant literature is reviewed.     

Parasellar dermoid tumor with intra-tumoral hemorrhage

We report a case of parasellar dermoid tumor with intra-tumoral hemorrhage. It is rare for a dermoid tumor that hemorrhage was detected as high attenuation on the initial CT. In the present case, the tumor content included a little fat component and mostly cholesterin-rich fluid which resulted in extremely low signal intensity on T2-weighted and high signal on T1-weighted MR images. In addition to this, hemosiderin accumulation in the tumor could be the reason for low signal intensity on T2-weighted images. Received 26 August 1997; Revision received 24 February 1998; Accepted 1998     

Increased signal intensity on fat-suppressed three-dimensional T1-weighted pulse sequences in patellar tendon: magic angle effect?

Objective. To assess the frequency of increased signal intensity in the patellar tendon using three-dimensional T1-weighted MRI pulse sequences. Design and patients. Sixty patients were examined with a 1.0 T scanner (15mT/m gradient strength) using a quadrature coil. Three pulse sequences were applied in the sagittal plane: PD turbo spin echo (PD-TSE), 3D T1-weighted gradient echo with fat suppression (3D-T1-FFE-FS) and 3D T1-weighted echo planar imaging with fat suppression (3D-T1-EPI-FS). The high signal intensity areas were measured in their maximum length. The angle of the patellar tendon relative to the main field position was measured in the same slice. In eight patients with anterior knee pain, and in 11 with no anterior knee pain, a fourth T2-weighted TSE pulse sequence (T2-TSE) was obtained to rule out patellar tendinitis. Results. The correlation of the high signal intensity areas with the relative position of the tendon was found to be significant with the 3D sequences (P=0.03 for 3D-T1-FFE-FS and P=0.003 for 3D-T1-EPI-FS). The length of the high signal intensity area in the tendon was 5.4 mm with 3D-T1-FFE-FS, 4.9 mm with 3D-T1-EPI-FS and 3.1 mm with PD-TSE images. No patellar tendinitis was demonstrated on the T2-TSE images. Conclusion. The magic angle effect is commonly observed in the 3D based T1-weighted pulse sequences with fat suppression. The presence of the above sign must be recognized by radiologists, so that misdiagnosis of patellar tendinitis is avoided. Received: 31 March 2000 Revision requested: 11 July 2000 Revision received: 2 August 2000 Accepted: 26 October 2000     

Variable MR findings in ovarian functional hemorrhagic cysts

PURPOSE: To describe the magnetic resonance (MR) findings in ovarian functional hemorrhagic cysts (FHC). MATERIALS AND METHODS: A total of 21 patients with 22 FHC, proven by follow-up ultrasound (US) in 11 women and surgery in 10 women, had US and MR examinations within 24 hours. The study was limited to cysts with obvious an echogenic pattern. All patients had T2-weighted fast spin echo (FSE), T1-weighted spin echo (SE), and T1-weighted SE fat-suppressed sequences. RESULTS: Four cysts (18%) were hypointense on T1-weighted-images without and with fat suppression, and hyperintense on T2-weighted-images. Five cysts (23%) were hypointense on T1-weighted images without and with fat suppression but heterogenous on T2-weighted images. Five cysts (23%) were hypointense on T1-weighted images but showed intermediate signal intensity on T1-weighted fat suppression images and heterogenous signal intensity on T2-weighted images. Two cysts (9%) were entirely intermediate on T1-weighted images. Five cysts (23%) displayed high signal intensity occupying less than 30% of the cystic content on T1-weighted images and one cyst (5%) displayed high signal intensity occupying more than 30% of the cystic content. CONCLUSION: Despite an obvious echogenic pattern on US, 64% of FHC were hypointense on T1-weighted images and 18% were also hyperintense on T2-weighted images. Only 36% demonstrated intermediate or high signal intensity on T1-weighted images.     

MRI of pancreatic tumors

MRI employing current imaging techniques is able to detect various pancreatic tumors well, and is able to stage and characterize tumors accurately. This review article describes various current MR techniques emphasizing breath hold spoiled gradient echo (SGE) imaging, fat suppression, dynamic gadolinium administration and MR cholangiographic techniques. Pancreatic ductal adenocarcinomas are generally low signal intensity on T1-weighted and T2-weighted images and enhance poorly on immediate post gadolinium SGE images. Islet cell tumors are generally low signal intensity on T1-weighted images, high signal intensity on T2-weighted images and enhance intensely on immediate post gadolinium images. The appearances of less common tumors is also described. Received 23 September 1996; Revision received 14 November 1996; Accepted 22 November 1996     

Phalangeal microgeodic syndrome: MR appearance

The authors describe the MR features of a case of microgeodic phalangeal syndrome in a 9-year-old boy. Roentgenograms showed multiple small areas of osteolysis in the middle phalanx of the right index finger. T1-weighted MR images showed lesions with diffuse low signal intensity not only in this phalanx but also in other phalanges. These lesions exhibited high signal intensity on T2-weighted images. Contrast- enhanced T1-weighted images showed a wide non-enhancing area in the middle phalanx of the index finger. Received: 26 September 2000 Revision requested: 2 November 2000 Revision received: 25 November 2000 Accepted: 27 November 2000     

Subchondral insufficiency fracture of the femoral head: histopathologic correlation with MRI

Objective. To correlate the magnetic resonance imaging (MRI) features with the histopathologic findings in subchondral insufficiency fracture (SIF) of the femoral head. Design and patients. This study was based on a retrospective review of the MRI features and histopathologic findings in seven patients with SIF who had had total hip replacement. Results. In all seven cases, MRI showed a bone marrow edema pattern in the femoral head, and a focal low-intensity band beneath the articular cartilage on some slices (not all) on the T1-weighted images. The shape of the low-intensity band varied: it was irregular and serpentine in four cases, well-delineated, smooth, and a mirror image to the articular surface in two cases, and parallel to the articular surface in one case. On histologic examination, the low-intensity band on MRI corresponded to a fracture line and its associated repair tissue. In all but one case, the band was not visible on T2-weighted or fat suppression images, and the proximal subchondral portion of the lesion had a homogeneous high signal intensity. This region of high signal intensity corresponded histopathologically to viable bone and marrow tissue with associated callus, edema, and vascular granulation tissue. Conclusions. SIF of the femoral head characteristically demonstrates a low-intensity band on T1-weighted images that corresponds, histopathologically, to a linear subchondral fracture and its associated repair tissue. In most cases, the subchondral portion of the lesion appears on T2-weighted images as an area of homogeneously high signal intensity. Received: 1 June 2000 Revision requested: 17 August 2000 Revision received: 11 October 2000 Accepted: 9 January 2001     

MR imaging of clear cell sarcoma (malignant melanoma of the soft parts): a multicenter correlative MRI-pathology study of 21 cases and literature review

Objective. To evaluate MR imaging and pathology findings in order to define the characteristic features of clear cell sarcoma of the soft tissues (malignant melanoma of the soft parts). Design and patients. MR examinations of 21 patients with histologically proven clear cell sarcoma of the musculoskeletal system were retrospectively reviewed and assessed for shape, homogeneity, delineation, signal intensities on T1- and T2-weighted images, contrast enhancement, relationship with adjacent fascia or tendon, secondary bone involvement, and intratumoral necrosis. In 19 cases the pathology findings were available for review and for a comparative MR-pathology study. Results. On T1-weighted images, lesions were isointense (n=3), hypointense (n=7) or slightly hyperintense to muscle (n=11). Immunohistochemical examination was performed in 17 patients. All 17 specimens showed positivity for HMB-45 antibody. In nine of 11 lesions with slightly increased signal intensity on T1-weighted images, a correlative MR imaging-pathology study was possible. All nine were positive to HMB-45 antibody. Conclusions. Clear cell sarcoma of the musculoskeletal system often has a benign-looking appearance on MR images. In up to 52% of patients, this lesion with melanocytic differentiation has slightly increased signal intensity on T1-weighted images compared with muscle. As the presence of this relative higher signal intensity on T1-weighted images is rather specific for tumors displaying melanocytic differentiation, radiologists should familiarize themselves with this rare entity and include it in their differential diagnosis when confronted with a well-defined, homogeneous, strongly enhancing mass with slightly higher signal intensity compared with muscle on native T1-weighted images. Received: 18 October 1999 Revision requested: 19 November 1999 Revision received: 21 January 2000 Accepted: 25 January 2000     

Fibrolipomatous hamartoma: pathognomonic on MR imaging

Purpose. To assess the MR imaging characteristics, presenting symptoms, age and nerve distribution of fibrolipomatous hamartoma. Design. A computer search was performed of the term fibrolipomatous hamartoma through the musculoskeletal section MR imaging results at our institution from June 7, 1996 to January 21, 1998 followed by a search of the terms lipomatous hamartoma, median nerve, surrounding fat, increased fatty signal, coaxial, and neuroma. MR images and medical files were retrospectively reviewed by two experienced musculoskeletal radiologists for imaging characteristics, nerve and age distribution as well as for history of trauma. In addition three consultation cases from outside institutions were added for determination of image characteristics. Results. Ten fibrolipomatous hamartomas were identified: eight in the median nerve, one in the ulnar nerve and one in the sciatic nerve. Mean age was 32.3 years (range 4–75 years, SD 21 years). Imaging characteristics were serpiginous low-intensity structures representing thickened nerve fascicles, surrounded by evenly distributed fat, high signal intensity on T1-weighted sequences and low signal intensity on T2-weighted sequences. The amount of fat varied; however, distribution in eight cases (80%) was predominantly between nerve fibers rather than surrounding them peripherally. All had a coaxial-cable-like appearance on axial planes and a spaghetti-like appearance on coronal planes that was not seen in any other type of median nerve abnormality imaged during the study period. Conclusion. The MR imaging characteristics of fibrolipomatous hamartoma are pathognomonic, obviating the need for biopsy for diagnosis. Received: 19 October 1998 Revision requested: 11 December 1998 Revision received: 22 January 1999 Accepted: 25 January 1999     

High intensity signal of the posterior pituitary. A study with horizontal direction of frequency-encoding and fat suppression MR techniques

PURPOSE: To evaluate the consistency of fat in the high intensity signals of the normal neurohypophysis and to differentiate the high signal of posterior pituitary from that of dorsum sella. Sagittal SE T1-weighted images with frequency encoding in the horizontal direction were used in order to differentiate the high signal of posterior pituitary and dorsum sella by the vertically-oriented chemical shift artifact. MATERIAL AND METHODS: The sellae of 46 normal volunteers were imaged with a commercially available fat suppression technique and SE sequences with frequency encoding in vertical (25 cases) and horizontal (21 cases) axes. RESULTS: The high signal intensity was absent in 9% of the normal volunteers with no predilection to any specific age group. None of the cases with posterior pituitary high intensity signals showed suppression of the signal with fat suppression technique. A fat suppression technique was helpful in documenting the hyperintensity in 7% of normal volunteers. Nineteen of the 21 (90%) cases with high signal intensity were detected by routine SE T1-weighted images, whereas 18 of the 19 (95%) cases were detected by imaging with frequency encoding in the horizontal direction. CONCLUSION: The high signal does not indicate the presence of fat. Fat suppression technique and a horizontal direction of frequency encoding help in differentiating the high signal of the neurohypophysis from that of dorsum sella.     

Traumatic adrenal hemorrhage: radiologic findings

Four patients with traumatic hemorrhage in the right adrenal gland were examined with computed tomography (CT) and ultrasound (US) (initial US studies in three patients; follow-up study at least 1 month after the trauma in all patients). CT showed an enlarged inhomogeneous gland of normal to increased attenuation. This finding was associated with stranding of the periadrenal fat and stranding of the subcutaneous fat of the right flank, which corresponded to the site of trauma. US showed an enlarged, hyperechoic mass with a bright central echo that became cystic on follow-up examinations. Magnetic resonance imaging, performed in one patient, showed an enlarged gland that was isointense with liver on T1-weighted images and had increased signal intensity on T2-weighted images. Stranding of the periadrenal and subcutaneous fat of the right flank was present on T2-weighted images and appeared as streaky areas of increased signal intensity.     

四肢黏液样脂肪肉瘤的MRI诊断

目的探讨四肢黏液样脂肪肉瘤的临床和MRI特点。方法对7例经病理证实的四肢黏液样脂肪肉瘤的临床和MRI资料进行了回顾性分析。患者年龄41-59岁，中位年龄51岁。结果3例肿瘤发生在大腿，2例在小腿，1例在足部，1例在肩部；6例位置深在，1例位置表浅。与肌肉相比病变在T1WI上主要呈等或稍低信号，6例可见“线”状、“花边”状或“云絮”状高信号；在T2WI上病变与脂肪相比大部分区域呈高信号；增强扫描病变均呈不均匀的显著强化；病变内部可见分隔，边缘清楚，周围无明显水肿，均未侵犯邻近骨骼。结论四肢黏液样脂肪肉瘤MRI表现有一定特点，在T1WI上主要呈等或稍低于肌肉的信号，并可见脂肪成分所致的“线”状、“花边”状或“云絮”状高信号，在T2WI上则以高于脂肪的信号为主，增强扫描呈不均匀的显著强化。     

Marginal erosive discovertebral ”Romanus” lesions in ankylosing spondylitis demonstrated by contrast enhanced Gd-DTPA magnetic resonance imaging

Objective. To assess the value of Gd-DTPA magnetic resonance (MR) imaging in the demonstration of marginal destructive discovertebral Romanus lesions in ankylosing spondylitis. Design and patients. A prospective study of Gd-DTPA MR imaging was performed in 39 patients with a clinical diagnosis of ankylosing spondylitis and typical Romanus lesions seen on radiographs of the thoracolumbar spine. MR morphological appearances and signal intensity changes at the discovertebral junctions were analysed and compared with the radiographic findings. Results. Ninety-nine discovertebral junctions with Romanus lesions showed low signal intensity on T1-weighted and high signal on T2-weighted and T1-weighted postcontrast images at the vertebral corners consistent with oedematous hyperaemic inflammatory tissue. There were nine discovertebral junctions with similar MR findings but normal radiographs. Fifty-three discovertebral junctions showed syndesmophyte formation with increased signal intensity on both T1- and T2-weighted images with no contrast enhancement. Sixty-five discovertebral junctions showed a mixture of radiographic features and varied high and low signal changes at the vertebral rim on MR imaging with rims of enhancement in the vertebral body following contrast administration. Conclusion. Gd-DTPA MR imaging demonstrates a variable signal pattern and degree of contrast enhancement which may reflect the evolutionary stages of discovertebral enthesitis in ankylosing spondylitis. MR imaging may identify early erosive changes in radiographically normal vertebra. The role of MR imaging needs further investigation. Received: 6 April 1998 Revision requested: 7 May 1998 Revision received: 26 October 1999 Accepted: 27 October 1999     

Granular cell tumor of the subcutis: CT and MRI findings

Three cases of granular cell tumor (GCT) of the subcutis are presented. Computed tomography showed a mass isodense with muscle with an ill-defined margin. Magnetic resonance imaging showed a mass with inhomogeneous low signal intensity on both T1- and T2-weighted images. Another characteristic feature of subcutaneous GCT is its attachment in part to muscle. Histological examination confirmed the diagnosis in all cases. Received: 20 July 1998; Revision requested: 12 October 1998; Revision received: 30 October 1998; Accepted: 16 November 1998     

CT and MR imaging features of oral and maxillofacial hemangioma and vascular malformation

PURPOSE: To present CT and MR images and compare CT and MRI features of oral and maxillofacial hemangioma and vascular malformation. MATERIAL AND METHODS: The clinical materials consisted of nine vascular tumors from nine patients examined by both CT and MR scanners between November 1996 and March 2002. Both CT and MR images were retrospectively evaluated. The following features were evaluated: detectability of the lesion, border of the lesion, tumor margin, inner nature of the lesion, contrast between the lesion and surrounding tissues, degree of CT value or signal intensity of the lesion, enhancement of contrast medium, inner nature of the lesion after contrast medium injection, detectability of phleboliths and detectability of bone resorption. RESULTS: In two patients, we could not detect lesions in any of the CT images because of artifacts from the teeth and/or dental restorations. In contrast, we could detect all lesions on T2-weighted MR images and contrast enhanced T1-weighted MR images. On T2-weighted images with the fat suppression technique, tumors tended to show higher contrast compared to surrounding tissues. CONCLUSION: T2-weighted images with the fat suppression technique and contrast enhanced T1-weighted images with the fat suppression technique were very useful for the detection of vascular lesions. Observation from optional directions (axial, coronal and sagittal images) seemed appropriate for delineating the extension of the tumor. Phleboliths detectability on CT images was superior to that on MR images.     

周围软组织血管瘤和血管畸形MRI鉴别诊断

目的探讨血管瘤和血管畸形MRI的鉴别诊断。方法回顾性分析61例手术证实的血管瘤和血管畸形MRI表现并与病理进行对照。结果29例血管瘤中,在T1WI上,20例为等信号(等于肌肉信号),9例为高等混杂信号;在T2WI上,24例呈较高信号(接近脂肪信号),5例呈高信号(高于脂肪信号),另见25例条状低信号分隔,其中4例增强呈分块状强化。32例血管畸形中,T1WI图,16例为等信号,16例为高等混杂信号;T2WI图,3例呈较高信号,29例呈高信号。其中15例增强呈不均匀强化。结论MRI对血管瘤和血管畸形的鉴别诊断有重要价值。