Hemorrhagic intracranial malignant neoplasms: spin-echo MR imaging

Twelve patients with 15 separate, spontaneously hemorrhagic, intracranial malignant lesions (seven primary gliomas, eight metastatic lesions) were examined with spin-echo magnetic resonance imaging at 1.5 T, and with computed tomography. The signal intensity patterns of these lesions, as seen on both short repetition time (TR)/short echo time (TE) and long-TR/long-TE spin-echo pulse sequences, were compared with the previously described appearance at 1.5 T of non-neoplastic intracerebral hematomas. The images of hemorrhagic intracranial malignancies showed notable signal heterogeneity, often with identifiable nonhemorrhagic tissue corresponding to tumor; diminished, irregular, or absent hemosiderin deposition; delayed hematoma evolution; and pronounced or persistent edema, compared with non-neoplastic hematomas. The demonstration of these characteristics in the appropriate clinical setting may suggest malignancy as the cause of an intracranial hematoma.     

Magnetic resonance imaging of disseminated bone marrow disease in patients treated for malignancy

Magnetic resonance imaging (MRI) is a sensitive method for the diagnosis of bone marrow abnormalities, but its usefulness in detecting active disseminated cancer in this tissue in treated patients has not been determined. We therefore examined 14 children who had been treated for disseminated bone marrow involvement by neuroblastoma (n=6), lymphoma (n=3), Ewing's sarcoma (n=3), osteosarcoma (n=1), and leukemia (n= 1). MRI studies were performed at 21 marrow sites to evaluate residual or recurrent tumor and were correlated with histologic material from the same site. T₁- and T₂-weighted sequences were employed in 21 and 14 studies, respectively; short tau inversion recovery (STIR) in 18; and static gadolinium diethylene triamine pentaacetic acid (Gd-DPTA)-enhanced, T₁-weighted sequences in 13. All MRI studies showed an altered bone marrow signal. Technetium 99m methylene diphosphonate (^99mTc-MDP) bone scintigraphy was also performed (19 studies). On histologic examination, 7 marrow specimens contained tumor, and 14 did not. Of the 7 tumor-positive lesions, all T₁-weighted, 4 of 6 T₂-weighted, and all 6 STIR sequences showed abnormal signal; all 5 GdDTPA-enhanced, T₁-weighted sequences showed enhancement of the lesion. However, abnormal signals were also observed on all T₁-weighted, 6 of 8 T₂-weighted, 11 of 12 STIR, and 5 of 8 Gd-DTPA-enhanced, T₁-weighted images of the tumor-negative sites. In this clinical setting, MRI did not consistently differentiate changes associated with treatment from malignant disease.     

The role of magnetic resonance imaging in the evaluation of Ewing sarcoma

The experience with magnetic resonance imaging (MRI) in 27 patients with Ewing sarcoma is reported and compared with computed tomography (CT) and plain films. Plain radiography proved to be the best imaging method to asses probable histological diagnosis in all cases (n=6). For the evaluation of chemotherapeutic response (n=4), CT and MRI gave the same information about the variation in size of the tumor. In this small series, the high signal in T2 weighted images was not altered significantly by therapy. In preoperative evaluation (n=14), MRI gave better information than CT of soft tissue involvement and extension within the bone marrow in two cases each. The ability of MRI to accurately define extension through the epiphyseal plate in two cases permitted limb salvage which otherwise would not have been possible. In the long-term follow-up (n=12), three patients without recurrence one year after therapy showed a low signal in the surgical area in T2 weighted images. Nine patients had a high signal in T2 weighted images: four were reactive lesions, two had obvious recurrence, and one was a hematoma. In the two remaining cases plain films and CT were normal, in the presence of both active tumor and reactive lesions. It was not possible with MRI to differentiate active tumor from reactive change, even after Gd-DTPA infusion.     

Abdominal tuberculous lymphadenopathy: MRI features

The aim of this study was to describe the MRI features of abdominal tuberculous lymphadenopathy. MRI studies of 13 patients with abdominal tuberculous lymphadenopathy were reviewed with regard to anatomic distribution and size. Signal intensities, in relation to abdominal wall muscle, on unenhanced T1- and T2-weighted images and patterns of contrast enhancement of lymphadenopathy were evaluated in each patient. In each patient, the largest lymph node with the same imaging characteristic was evaluated. The upper paraaortic region was the most common site of involvement (n=12 patients), followed by the lesser omentum (n=10 patients), the anterior pararenal space (n=9 patients), the lower paraaortic area (n=8 patients), the small bowel mesentery (n=6 patients), the greater omentum (n=2 patients) and the originating site of the inferior mesenteric artery (n=2 patients). The mean lymph node size was 1.8 cm (range 0.5–5 cm). The overall mean lymph node number per patient was 16 (range 2–50). A total of 41 lymph nodes were evaluated in 13 patients. On T2-weighted images, 40 lesions were hyperintense and one lesion was isointense. Nine hyperintense lesions showed a hypointense peripheral rim and seven internal heterogeneïty. Perinodal T2-hyperintensity was present in 23 lesions. The latter finding was valid for all patients. On T1-weighted images, 30 lesions were hypointense and 11 isointense. Nine hypointense lesions demonstrated a hyperintense peripheral rim, and six were heterogeneous. Contrast-enhanced fat-suppressed T1-weighted images demonstrated predominant peripheral enhancement in 28 lesions: (1) peripheral uniform, thin (n=19); (2) thick irregular, complete (n=3); and (3) conglomerate group of nodes showing peripheral and central areas of rim enhancement (n=6). Heterogeneous and homogeneous enhancement was present in ten and three lesions, respectively. Combinations of enhancing patterns in the same nodal group and different nodal groups were seen in eight and nine patients, respectively. Abdominal tuberculous lymphadenopathy may show a variety of signal intensities and patterns of contrast enhancement on MRI. Lymphadenopathy, hypointense on T1-weighted, hyperintense on T2-weighted images with perinodal hyperintensity, and predominant peripheral rimlike enhancement may suggest the diagnosis of tuberculosis.     

Gadopentetate-dimeglumine-enhanced MR imaging of osteonecrosis and osteochondritis dissecans of the elbow: initial experience

Magnetic resonance imaging (MRI) was performed on seven patients with aseptic osteonecrosis (n=4) and osteochondritis dissecans (OCD;n=3) of the elbow. Precontrast MRI was superior to plain radiographs, which did not show any abnormality in three cases of osteonecrosis. On gadopentetate-dimeglumine-enhanced T1-weighted images, which were obtained in three patients with osteonecrosis and three patients with OCD, all cases of osteonecrosis demonstrated homogeneous enhancement of the lesions. All cases of OCD were diagnosed on plain radiographs. On MRI one showed significant enhancement of the loose body. In another case an incompletely enhancing loose body was surrounded by a diffusely enhancing region. In the third patient only a small marginal enhancement of the defect was observed. Our results suggest that MRI can improve the accuracy in diagnosis of aseptic osteonecrosis of the elbow. The use of gadopentetate dimeglumine allows the viability of the lesions or the loose bodies to be demonstrated and reparative tissue to be detected.     

Chondroblastoma of the hands and feet

Objective To review the imaging findings, age and gender distribution of chondroblastoma of the hands and feet.Design and patients Twenty-five cases of pathologically proven chondroblastoma of the hands and feet were reviewed. Available imaging modalities included radiographs (n=24), CT (n=3), MRI (n=5), and radionuclide bone scintigraphy (n=1). The following imaging features for each case were tabulated: location, presence of sclerotic margin, calcification, expansion, presence of fluid/fluid levels on cross-sectional imaging and surrounding edema on MRI. The images were evaluated for skeletal maturity using closure of the physeal plate in the region as a standard.Results The average age at time of diagnosis was 23 years (range 7–57 years). Eighty-four percent (n=21) of the patients were skeletally mature. Males (20 of 25) outnumbered females by a ratio of 5:1. The bones of the foot accounted for 22 cases: calcaneus (n=8), talus (n=8), metatarsals (n=3), and the cuboid (n=3). The bones of the hand accounted for three cases: phalanx (n=1), triquetrum (n=1), and a metacarpal (n=1). Radiographically all lesions were osteolytic with identifiable calcification in 54% (13 of 24). Fluid/fluid levels were seen in four of five cases on MRI. Edema on MR images was seen in 40% (2 of 5). The size of the lesions ranged from 2 to 41 cm².Conclusion Chondroblastomas of the hands and feet share many of the radiographic characteristics seen in the long bones, but manifest in skeletally mature patients with a higher male to female ratio than in long bone chondroblastoma. Talar and calcaneal lesions were encountered only in males. Chondroblastoma of the wrist and hand appears to be exceptionally rare.Presented at the special scientific session of the International Skeletal Society held in San Francisco, California, USA, September 2003     

Alveolar soft part sarcoma: MR and angiographic findings

Objective. To present the MR and angiographic findings of alveolar soft part sarcoma (ASPS). Design and patients. MR examinations (12 tumors of 10 patients) of ASPS performed at multiple hospitals were retrospectively reviewed. The tumors were found in the thigh (n=4), lower leg (n=4), femur (n=2, local metastasis), scalp (n=1) and arm (n=1). The MR signal characteristics including signal intensity, homogeneity and signal void of lesions and bony invasion including direct invasion or local metastasis were evaluated. Angiographic findings (n=4) and post-embolotherapy follow-up MR imaging (n=2) findings were also assessed. Results. Local bony metastasis was found in two cases. Seven tumors showed heterogeneous high signal intensity on T1- and T2-weighted images with good enhancement. One tumor had a very high signal on T1-weighted images. Eight tumors (67%) showed numerous signal voids in or near the tumors. All four angiographic studies showed numerous enlarged vessels, arteriovenous shunts and delayed washout. Two cases mimicked arteriovenous malformations on angiographic studies but MR images demonstrated solid soft tissue components as well as tortuous vessels. Conclusions. High signal on T1-weighted image and numerous signal voids are highly suggestive of ASPS, although they are not universal as has been suggested and arteriovenous malformation should be included in the differential diagnosis. Local bony metastases in ASPS were seen in two cases and should be carefully investigated. Received: 12 April 2000 Revision requested: 27 June 2000, 8 August 2000 Revision received: 2 August 2000, 21 August 2000 Accepted: 22 August 2000     

Magnetic resonance imaging findings of intracranial papillary meningioma: a study on eight cases

ObjectivesTo increase the awareness on intracranial papillary meningiomas (PMs) by presenting magnetic resonance imaging (MRI) findings on this disease.Materials and methodsThe MRI findings and clinical presentations of nine discrete lesions in eight patients with pathologically documented PMs were retrospectively analyzed.ResultsMost tumors occurred in young adults. The tumors originated from the convexity meninges in five cases and from the parasagittal regions in four cases. The tumor shape was irregular in six cases, lobulated in two cases, and round in one case. By MRI, nine masses were primarily isointense (n=5) or mildly hypointense (n=4) to gray matter on T1-weighted images and inhomogeneous hyperintense (n=3) or isointense (n=6) to the cortex on T2-weighted and fluid-attenuated inversion recovery images. On diffusion-weighted imaging, the signal intensity of the tumor was increased in all lesions compared with the adjacent parenchyma. Tumor and brain interfaces were unclear in seven cases, cyst formation was observed in eight tumors, scattered hemorrhage was observed in three tumors, signal voids due to vessels were visible in four cases, and eight tumors had moderate or marked irregular peritumoral edema. Enhancement was homogeneous (n=2) or heterogeneous (n=7), an area of focal nodular enhancement was observed in three lesions, and the dural tail sign was visible in seven cases.ConclusionAlthough PM is rare, it should be considered in the differential diagnosis when evaluating intracranial neoplasms. Younger patient age, as well as imaging features such as unclear tumor–brain interface, internal heterogeneity including cyst formation, irregular enhancement, signal voids of vessels, and marked peritumoral edema can help distinguish PM from typical benign meningiomas.     

MRI features of tuberculosis of the knee

Objective  The objective of this study was to describe the magnetic resonance imaging (MRI) features of tuberculosis (TB) of the knee joint. Materials and methods  The MRI features in 15 patients with TB of the knee, as confirmed by histology of the biopsied joint synovium, were reviewed retrospectively. The images were assessed for intra-articular and peri-articular abnormalities. Results  All patients had florid synovial proliferation. The proliferating synovium showed intermediate to low T2 signal intensity. In the patients who were administered intravenous contrast, the hypertrophic synovium was intensely enhancing. Marrow edema (n = 9), osteomyelitis (n = 4), cortical erosions (n = 5), myositis (n = 6), cellulitis (n = 2), abscesses (n = 3), and skin ulceration/sinus formation (n = 2) were seen in the adjacent bone and soft tissue. Conclusion  Synovial proliferation associated with tuberculous arthritis is typically hypointense on T2-weighted images. This appearance, in conjunction with other peri-articular MRI features described, can help in distinguishing TB arthritis from other proliferating synovial arthropathies.     

Human fascioliasis: MR imaging findings of hepatic lesions

Our objective was to describe MR imaging findings of liver lesions in human fascioliasis. The MR imaging of the liver was performed in 29 patients with fascioliasis. Seventeen patients were women and 12 were men, with a mean age of 47.5 years (age range 17–75 years). Hepatic lesions were grouped into five types based on their signal characteristics. Three patients had normal imaging findings. One or more lesions were observed in the other 26 patients. The lesion types and the frequency of appearances were as follows: hyperintensity of the liver capsule on T2-weighted images (n=16, 55.2%); ill-defined slightly hyperintense areas on T2-weighted images (n=18, 62.1%); lesions which were hypointense on T1-weighted and hyperintense on T2-weighted images (n=10, 34.5%); hypointense on T1-weighted images and centrally hypo- or hyperintense, surrounded by peripherally less hyperintense area on T2-weighted images (n=4, 13.8%); and hypointense foci or ill-defined hypointense areas on T1- and T2-weighted images (n=10, 34.5%). We describe the MR imaging features of the disease. Our findings may help the differential diagnosis in which fascioliasis should be added to the list. Electronic Publication     

Synovial hemangioma: imaging features in eight histologically proven cases,review of the literature,and differential diagnosis

Objective This study was undertaken to describe the imaging characteristics of synovial hemangioma, with the goal of improving the disappointing rate (22%) of clinical diagnosis of this condition. A review of the literature and the differential diagnosis of intra-articular lesions, including synovial osteochondromatosis and pigmented villonodular synovitis, are also presented.Patients The subjects of the study were 8 patients (4 males, 4 females; age range: 5–47 years; mean age: 19 years) with histologically confirmed synovial hemangioma involving the knee (n=7) or wrist (n=1). We retrospectively examined the imaging studies performed in these patients, including plain radiography (n=8), magnetic resonance imaging (MRI; n=4), angiography (n=3), arthrography (n=2), and contrast-enhanced computed tomography (CT; n=2).Results Plain radiographs showed a soft tissue density suggesting either joint effusion or a mass in all patients. Phleboliths and bone erosions on plain films in four patients with extra-articular soft tissue involvement pointed to the correct diagnosis. Angiography, showing fine-caliber, smooth-walled vessels, contrast pooling in dilated vascular spaces, and early visualization of venous structures, was diagnostic in two patients. Neither arthrography nor CT yielded specific enough findings. MRI was consistently effective in allowing the correct diagnosis to be made preoperatively, showing an intra-articular or juxta-articular mass of intermediate signal intensity on T1-weighted images and of high signal intensity on T2or T2^*-weighted images with low-signal channels or septa within it. A fluid-fluid level was found in two patients with a cavernous-type lesion.Conclusion Despite the limited nature of this study, it shows clearly that MRI is the procedure of choice whenever an intra-articular vascular lesion such as synovial hemangioma is suspected. Nonetheless, phleboliths and evidence of extra-articular extension on plain radiographs point to angiography as an effective procedure of first resort because it can be combined with embolotherapy.     

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     

Preoperative breast MRI in patients with invasive lobular breast cancer

To investigate the use of MRI in preoperative characterization of invasive lobular breast cancer (ILC) and in detection of multifocal/multicentric disease. We retrospectively reviewed T1-weighted FLASH 3D precontrast and postcontrast MR images together with subtraction images of 26 women with histopathologically proven invasive lobular cancer. Two experienced radiologists described tumor patterns of ILC independently. MR findings of unifocal, multifocal, single quadrant and multiquadrant disease were correlated with results of other imaging techniques and compared with histopathological findings as gold standard. Most ILC presented on MRI as a single spiculated/irregular, inhomogeneous mass (pattern 1, n=12) or as a dominant lesion surrounded by multiple small enhancing foci (pattern 2, n=8). Multiple small enhancing foci with interconnecting enhancing strands (pattern 3) and an architectural distortion (pattern 4) were both described in three cases. There was one case of a focal area of inhomogeneous enhancement (pattern 5) and one normal MR examination (pattern 6). Unifocal and multifocal lesions were identified on MRI in four patients with normal conventional imaging. In nine women, multiple additional lesions or more extensive multiquadrant disease were correctly identified only on MRI. MRI may play an important role in the evaluation of patients with ILC, which is often difficult to diagnose on clinical examination and conventional imaging and more likely occur in multiple sites and in both breasts. However, false-negative MR findings do occur in a small percentage of ILC.     

Gastrointestinal stromal tumors: CT and MRI findings

The objective of this study was to report the CT and MRI appearances of primary and metastatic gastrointestinal stromal tumor (GIST). The clinical and imaging findings of 31 patients with histological and immunohistochemical diagnosis of GIST were reviewed. The CT and MRI findings were assessed independently for size, location, enhancement characteristics, and pattern of metastatic disease. The tumors were of enteric (n=13), gastric (n=12), duodenal (n=2), and rectal (n=3) origin. In one case the primary site was the mesentery, without involvement of bowel. Primary tumors were typically exophytic (79%), larger than 5 cm (84%), and inhomogeneously enhancing (84%). Central necrosis of all tumors (37%) and aneurysmal dilation of enteric tumors (33%) were less common. Metastases were most commonly to mesentery (26%) or liver (32%). Less common findings were ascites (7%) and omental caking (3%). Liver metastases were hypervascular in 92% of patients and rapidly became cystic following therapy with imatinib mesylate (Gleevec; Novartis, East Hanover, NJ, USA). Lung metastases, bowel obstruction, vascular invasion, and significant lymphadenopathy were not seen in any patient. GISTs have some specific CT findings which could help differentiate them from other gastrointestinal tumors. Liver metastases became cystic following therapy, mimicking simple cysts. MRI was better than single-phase CT for assessing liver metastases, while CT was more sensitive for mesenteric metastases.     

MDCT and superparamagnetic iron oxide (SPIO)-enhanced MR findings of intrapancreatic accessory spleen in seven patients

The aim of this study is to retrospectively evaluate intrapancreatic accessory spleen (IPAS) with mutidetector computed tomography (MDCT) and superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) with emphasis on the role of SPIO-MRI for the diagnosis of IPAS. Seven patients (four men and three women; mean age, 50.7 years) with IPAS underwent quadriphasic MDCT and SPIO-enhanced MRI. IPAS was diagnosed histopathologically (n=2) or by scintigraphy (n=5). Two radiologists evaluated CT and MRI in consensus for the location and size of each lesion and compared its attenuation on CT and signal intensity (SI) on MRI with those of the pancreas and spleen. For quantitative analysis, another radiologist calculated the mean lesional, pancreatic, and splenic attenuations or SIs on MDCT or MRI in each patient. All lesions were located in the pancreatic tail. The average lesion size was 1.5±0.5 cm. All IPASs except one appeared high-attenuating to the pancreas and were isoattenuating to the spleen on all dynamic CT phases. The IPASs were hypointense and hyperintense compared with the pancreas on unenhanced T1- and T2-weighted images, respectively, and their SI was similar to that of the spleen. On SPIO-enhanced, T2-weighted images, a similar degree of signal drop to that of the spleen was noted in all lesions. The results of the quantitative analysis were compatible with those of the subjective analysis. In most IPASs, the attenuation on CT and SI on MRI were identical to those of the spleen, and on SPIO-enhanced MRI, the degree of the signal drop in all lesions was similar to that of the spleen.     

Symmetrical central tegmental tract (CTT) hyperintense lesions on magnetic resonance imaging in children

The central tegmental tract (CTT) is mainly the extrapyramidal tract connecting between the red nucleus and the inferior olivary nucleus. There are only a few case reports describing CTT abnormalities on magnetic resonance imaging (MRI) in children. Our purpose was to evaluate the frequency of CTT lesions and their characteristics on MRI, and to correlate the MR imaging findings with clinical features. We reviewed retrospectively the MR images of 392 children (215 boys and 177 girls) ranging in age from 1 to 6 years. To evaluate symmetrical CTT hyperintense lesions, we defined a CTT lesion as an area of bilateral symmetrical hyperintensity in the tegmentum pontis on both T2-weighted images and diffusion-weighted images in more than two slices. We measured the ADC (apparent diffusion coefficient) values of symmetrical CTT hyperintensity, and compared them with those of children without CTT abnormality. CTT lesions were detected in 20 (5.1%) of the 392 children. The mean ADC value for these 20 children was significantly lower than that of the normal CTT (p < 0.001). On MR imaging, other than CTT lesions, associated parenchymal lesion included: none (n = 6); other abnormalities, including periventricular leukomalacia (n = 3); thin corpus callosum (n = 3); ventricular dilatation (n = 2); encephalopathy (n = 2). Clinically, cerebral palsy was the most frequent clinical diagnosis (n = 6), accounting for 30%, which was significantly more frequent than the prevalence of cerebral palsy among children without CTT lesions (13%) (n < 0.05). CTT lesions were detected in 5.1% of all the children examined. Cerebral palsy was the most frequent clinical diagnosis.     

Aggressive fibromatosis: MRI features with pathologic correlation

OBJECTIVE: We present the MRI features with pathologic correlation of aggressive fibromatosis, incorporating 203 cases over a 5-year period from the Royal Marsden Hospital Sarcoma Unit database. MATERIALS AND METHODS: Sixty patients had imaging available for retrospective review of which 29 had preoperative MRI and final histopathologic diagnosis of aggressive fibromatosis. RESULTS: The average age at diagnosis was 41.3 years with a female-to-male sex ratio of 1.2:1. Twenty lesions were extraabdominal; six, intraabdominal; and three, in the abdominal wall (classic desmoid). The average tumor size was 6.4 cm (range, 2.2-13.7 cm). Intraabdominal aggressive fibromatosis produced the largest tumors, averaging 9.5 cm. Most lesions were ovoid (52%) or infiltrative (34.5%) in outline with an irregular or lobulated contour (76%). The lesions crossed major fascial boundaries in 31% of cases overall and in 66% of patients referred for recurrent disease. On MRI, homogeneous isointensity or mild hyperintensity on T1-weighted images and heterogenous high signal on T2-weighted or STIR images were seen. All lesions enhanced after IV gadolinium, usually avidly. In contrast to previous reports, 38% of cases failed to show low signal on all pulse sequences and no abnormalities were seen in local bone structures. Histology showed sheets of bland spindle cells in dense collagen and did not vary with the MRI signal characteristics of the lesion. Patients referred for recurrent disease were most likely to have a recurrence after surgery. MRI and pathology findings did not predict recurrence. CONCLUSION: Accurate diagnosis and staging of aggressive fibromatosis by MRI have important treatment and prognostic implications.     

Magnetic resonance signal alterations in the acute onset of heterotopic ossification in patients with spinal cord injury

The purpose of our study was to evaluate magnetic resonance (MR) signal characteristics of acutely forming heterotopic ossification (HO) in paralyzed patients. Fourteen patients with spinal cord injury (female n=2, male n=12, mean age 38.3 years) and acute onset of radiographically proven HO had contrast-enhanced 1.5-T MRI within 13.4±18.3 days of clinical onset of symptoms. MR signal alterations of affected muscles, fascia, subcutaneous tissue, skin and adjacent bone were evaluated. A diffuse T2-hyperintense signal of multiple muscle groups was seen in all patients (bilateral in 12) involving quadriceps (n=13, 93%), adductors (n=13, 93%) and iliopsoas (n=12, 86%) with contrast enhancement in n=11 (79%), n=8 (57%) and n=8 (57%) patients. All patients had nonenhancing areas (mean size 2×3.5×5.8 cm) within diffusely enhancing muscles. HO formation occurred around these nonenhancing areas in four patients with computed tomography follow-up. Other MR findings included fascial edema (n=14, 100%), fascial enhancement (n=13, 93%), subcutaneous edema (n=13, 93%), subcutaneous enhancement (n=12, 86%), bone marrow edema (n=5, 36%), and joint effusion (n=12, 86%). MRI reveals mostly bilateral edema and enhancement of muscles, fascia and subcutaneous tissue during acute onset of HO. HO develops in the periphery of well-defined areas of no enhancement.     

MR findings of Rosai-Dorfman disease in sellar and suprasellar region

Background

Rosai–Dorfman disease (RDD) in sellar/suprasellar region is a rare intracranial disorder. The diagnostic evaluation of this condition using magnetic resonance imaging (MRI) has seldom been described previously. The purpose of our study was to describe MRI characteristics of sellar/suprasellar region RDD.

Methods

Five patients with proved sellar/suprasellar region RDD from May 2005 to March 2010 were retrospectively reviewed. All the patients had undergone magnetic resonance scanning. The number, location, signal intensity (SI), and enhancement pattern of the lesions on MRI were retrospectively evaluated.

Results

Pathological diagnosis of RDD was achieved in all 5 cases including 4 by surgery and 1 by biopsy. The most common presenting symptoms were headache (n = 4) and blurred vision (n = 3). On MRI, isolated suprasellar lesion was found in 2 cases. Suprasellar lesion combined with intrasellar, dural, intra-axial and orbital lesions was found in 3 cases. All lesions showed homogeneous isointense SI on T1-weighted images and hypointense to isointense SI on T2-weighted images except one lesion in the midbrain with slight hyperintense SI on T2-weighted images. All lesions showed homogeneous enhancement.

Conclusion

Homogenously enhancing sellar/suprasellar masses of hypointense to isointense SI on T2-weighted images are suggestive of RDD, and central hypointensity on T2-weighted images may be a specific finding. Intra-axial and extra-axial involvements may coexist with sellar/suprasellar region RDD. Although radiological findings can provide some evidence for this rare entity, differential diagnosis is still needed.     

Capillary telangiectasias of the pons. Does diffusion-weighted MR increase diagnostic accuracy?

Background and Purpose

Capillary telangiectasias are benign lesions of the brainstem which are sometimes difficult to distinguish from other lesions in standard MRI. The purpose of this study was to evaluate if diffusion-weighted imaging (DWI) could help to improve diagnostic accuracy.

Methods

148 MR examinations of patients with pontine lesions were evaluated retrospectively and revealed capillary telangiectasia (n = 18), presumed microvascular disease (n = 20), encephalitis disseminata (n = 21), pontine myelinolysis (n = 16), tumor (n = 20), acute infarction (n = 20), subacute infarction (n = 13) and chronic infarction (n = 20).All patients were examined using identical measurement parameters for DWI, Fluid attenuated inversion recovery, T2-weighted turbo spin-echo, and T1-weighted spin-echo before and after application of contrast agent in transverse orientation.

Results

All capillary telangiectasias showed low signal intensity in DWI and significant contrast enhancement after application of gadolinium. Hypointense signal on DWI was very rare for the remaining lesions: only 1 pontine myelinolysis, 1 tumor, 4 subacute infarctions, and 19 chronic infarctions also revealed low signal intensity on DWI. The combination of high signal intensity on T1-weighted post-contrast images and low signal intensity on DWI was found for all capillary telangiectasias, but only for 1/20 tumor and for 4/13 subacute infarctions. These lesions could be differentiated by their clinical course and/or MRI follow-up examinations.The results of the visual assessment were confirmed by quantitative evaluation.

Conclusion

DWI seems to be a useful adjunct for the diagnosis of capillary telangiectasias which will facilitate the differential diagnosis concerning tumorous, inflammatory and ischemic lesions.