Magnetic resonance imaging of intramuscular myxoma with histological comparison and a review of the literature

Objective To evaluate the magnetic resonance (MR) features of intramuscular myxoma (IM) compared with its pathological findings.Design Two radiologists retrospectively reviewed records and imaging studies of patients with histologically proven IM. Two radiologists also analyzed by consensus all the MR studies (pre- and post-contrast T1-weighted and T2-weighted sequences) and a pathologist reviewed the available histological material.Patients Seventeen patients with 18 histologically proven IM were reviewed. Histological samples of 11 of these 18 tumors were available for pathological analysis.Results There were 14 women and three men, with a mean age of 58.9 years. IM involved predominantly the thigh (n=10). MR imaging showed well-circumscribed intramuscular masses, hypointense on T1-weighted and hyperintense on T2-weighted images. Eleven masses were homogeneous and seven slightly heterogeneous due to fibrous septa. Enhanced MR imaging demonstrated three different patterns: peripheral enhancement (n=1), peripheral and patchy internal enhancement (n=7) or peripheral and linear internal enhancement (n=4). Intratumoral cysts were detected in four masses. MR imaging showed the presence of a pseudocapsule (n=12), fat around the lesion (n=16) and peritumoral edema (n=16). Histologically, all the tumors were hypocellular, hypovascular and myxoid. Peripheral areas of collagenous fibers formed a partial capsule and IM often merged into surrounding muscular fibers. More cellular tumors and those with scanty myxoid stroma tended to show a more prominent internal enhancement.Conclusion IM shows several recognizable MR features which suggest its diagnosis.     

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     

Subcutaneous and musculoskeletal sparganosis: imaging characteristics and pathologic correlation

Objective. To document the imaging characteristics of subcutaneous and musculoskeletal sparganosis. Design and patients. Ten patients with musculoskeletal sparganosis were examined, with a variety of imaging modalities including MRI (n=6), ultrasonography (n=8), plain radiography (n=7) and CT (n=1). Pathologic correlation was carried out in all cases. Results. Nine lesions involved soft tissues, of which seven were in the thigh, two in the trunk and one involved a vertebral body. The majority of the lesions in soft tissue were confined to the subcutaneous layer but two extended deep into underlying muscles. Sonography revealed low-echoic serpiginous tubular tracts (8/8), and an intraluminal echogenic structure (4/8). MRI revealed multiple serpiginous tubular tracts and peripheral rim enhancement. Two patients showed perilesional soft tissue edema. Pathologically, the lesion consisted of a larva surrounded by three layers of inflammation: an inner epithelioid granulomatous cell layer, middle chronic inflammatory cell layers, and an outer fibrous layer. Conclusion. The study suggests that if serpiginous tubular tracts are seen at imaging studies, musculoskeletal sparganosis should be included in the differential diagnosis. Received: 27 July 1999 Revision requested: 20 September 1999 Revision received: 11 February 2000 Accepted: 14 March 2000     

Quadriceps fat pad edema: significance on magnetic resonance images of the knee

Objective While clinically reading magnetic resonance (MR) images of the knees we have occasionally noted edema within the suprapatellar fat pad, with mass effect both on the suprapatellar joint recess posteriorly, and on the quadriceps tendon anteriorly. This MR appearance is analogous to Hoffa’s disease described in the infrapatellar fat pad. We sought to evaluate the frequency and pattern of this finding and to provide clinical and histological correlation. Patients The suprapatellar (quadriceps) fat pad was evaluated in 770 consecutive MR examinations (on 1.5 T and 0.3 T) in 736 patients (353 females and 383 males, age range 5–86 years, mean 44.3 years). Design The MR images were retrospectively evaluated by two observers in consensus for the presence of quadriceps fat pad edema with mass effect. In 46 patients who had intravenous administration of gadolinium, the presence of enhancement was also evaluated. Clinical correlation was performed in abnormal cases; in one patient, 1-year follow-up MRI was evaluated and in one patient a percutaneous biopsy as well as 2-year clinical follow-up was performed. Results Thirty-two (4.2%) knees in 29 patients showed quadriceps fat pad edema and mass effect. In five of these patients imaging of the contralateral knee was also performed and four of these showed symmetric edema. Another five cases had gadolinium-enhanced images with prominent enhancement. Most patients had clinical symptoms of meniscal tears (n=16, 55%) or anterior knee pain (n=8, 27.6%). The remainder had nonspecific pain (n=4, 13.8%) or suspected avascular necrosis (n=1, 3.4%). In the case with 1-year follow-up MRI, improvement was seen. Biopsy in another patient revealed vasculitis with obliteration of the small vessels. Resection of the fat pad in this patient led to complete resolution of the symptoms. Conclusion Suprapatellar fat pad edema may be analogous to Hoffa’s disease, is rare, and may be a cause of anterior knee pain. However, this finding is not infrequent and its precise association with symptoms remains unclear. The study was done when all authors worked at Thomas Jefferson Medical College.     

Differentiating high-grade from low-grade chondrosarcoma with MR imaging

The purpose of the study was to evaluate the MR imaging features that differentiate between low-grade chondrosarcoma (LGCS) and high-grade chondrosarcoma (HGCS) and to determine the most reliable predictors for differentiation. MR images of 42 pathologically proven chondrosarcomas (28 LGCS and 14 HGCS) were retrospectively reviewed. There were 13 male and 29 female patients with an age range of 23–72 years (average age 51 years). On MR images, signal intensity, specific morphological characteristics including entrapped fat, internal lobular architecture, and outer lobular margin, soft tissue mass formation and contrast enhancement pattern were analysed. MR imaging features used to identify LGCS and HGCS were compared using univariate analysis and multivariate stepwise logistic regression analysis. On T1-weighted images, a central area of high signal intensity, which was not seen in LGCS, was frequently observed in HGCS (n = 5, 36%) (p < 0.01). Entrapped fat within the tumour was commonly seen in LGCS (n = 26, 93%), but not in HGCS (n = 1, 4%) (p < 0.01). LGCS more commonly (n = 24, 86%) preserved the characteristic internal lobular structures within the tumour than HGCSs (n = 4, 29%) (p < 0.01). Soft tissue formation was more frequently observed in HGCS (n = 11, 79%) than in LGCS (n = 1, 4%) (p < 0.01). On gadolinium-enhanced images, large central nonenhancing areas were exhibited in only two (7.1%) of LGCS, while HGCS frequently (n = 9, 64%) had a central nonenhancing portion (p < 0.01). Results of multivariate stepwise logistic regression analysis showed that soft tissue formation and entrapped fat within the tumour were the variables that could be used to independently differentiate LGCS from HGCS. There were several MR imaging features of chondrosarcoma that could be helpful in distinguishing HGCS from LGCS. Among them, soft tissue mass formation favoured the diagnosis of HGCS, and entrapped fat within the tumour was highly indicative of LGCS.     

Diagnostic value of delineating deep fascia in distinguishing between benign and malignant soft-tissue tumors in lower limbs using 3.0 T magnetic resonance imaging

Purpose

To determine the association between morphological changes to the deep fascia and the malignancy of soft‐tissue tumors in the lower limbs using 3.0 T magnetic resonance imaging (MRI).

Materials and Methods

MR images of 47 consecutive patients with 48 pathologically proven soft‐tissue tumors in the lower limbs were retrospectively reviewed by two radiologists. Lesions were divided into four groups according to their predominant location relative to the deep fascia: Group A: subcutaneous lesions superficial to the deep fascia (n = 9); Group B: lesions located beneath the deep fascia (n = 8); Group C: lesions centered in the interspaces of the deep fascia investment (n = 11); and Group D: intramuscular lesions (n = 20).

Results

The deep fascial structures were complete in all of the 19 benign lesions. In malignant lesions, destruction signs of the deep fascia were observed in 27 of the 29, which were characterized by disappearance/disruption of the fascial line and aggressive growth penetrating through the fascial line into the adjacent compartment, or disappearance/disruption of the intermuscular septa and embedding the mutilated fascial septa within the lesion, or destruction of the fascia‐muscle planes and abolishment of the deep fascial interspaces. Diagnosis of malignancy based on the signs of destruction of the deep fascial structure delineated with 3.0 T MRI, the sensitivity, specificity, and accuracy were 93.10%, 100%, and 95.83%, respectively.

Conclusion

Tumor involvement and destruction of the deep fascial structures visualized by 3.0 T MRI may be of utility in differentiating malignant from benign soft‐tissue tumors. J. Magn. Reson. Imaging 2011;33:173–179. © 2010 Wiley‐Liss, Inc.     

Adhesive capsulitis of the shoulder: evaluation with MR arthrography

The purpose of this study was to determine the usefulness of magnetic resonance (MR) arthrography for diagnosing adhesive capsulitis. Shoulder MR images of 28 patients with (n=14) and without (n=14) adhesive capsulitis were retrospectively analyzed. MR images were assessed for capsule and synovium thickness as well as the width of the axillary recess on oblique coronal fat-suppressed T1-weighted images and T2-weighted images, respectively. On oblique sagittal fat-suppressed T1-weighted images, the width of the rotator interval and the presence of abnormal tissue in the interval were evaluated. Significant differences were found between the two groups in capsule and synovium thickness on both sides of the recess on oblique coronal T2-weighted images (P=0.000), whereas thickness on the humeral aspect showed no significant difference on oblique coronal fat-suppressed T1-weighted images (P=0.109). On oblique coronal T2-weighted images, a cut-off value of 3-mm thickness gave the highest diagnostic accuracy for adhesive capsulitis with sensitivity, specificity, and accuracy of 79% (11/14), 100% (14/14), and 89% (25/28) at the humeral side and 93% (13/14), 86% (12/14), and 89% (25/28) at the glenoid side, respectively. There were significant differences in rotator interval width, presence of abnormal tissue in the rotator interval, and axillary recess width between the two groups (P<0.05). Thickness of capsule and synovium of the axillary recess greater than 3 mm is a practical MR criterion for diagnosing adhesive capsulitis when measured on oblique coronal T2-weighted MR arthrography images without fat suppression. The presence of abnormal tissue in the rotator interval showed high sensitivity but rather low specificity.     

Characteristics and pitfalls of contrast-enhanced, T1-weighted magnetization transfer images of the brain

RATIONALE AND OBJECTIVES: This study was undertaken to clarify the difference in signal pattern on contrast material-enhanced T1-weighted magnetic resonance (MR) magnetization transfer (MT) images between enhancing and nonenhancing lesions in various intracranial diseases and to determine the necessity of nonenhanced MT images for evaluating lesional contrast enhancement. MATERIALS AND METHODS: MR images of 116 patients who underwent nonenhanced T1-weighted imaging, nonenhanced MT imaging, and contrast-enhanced MT imaging were reviewed. The increase in signal intensity of lesions relative to normal brain was compared between nonenhanced T1-weighted images and contrast-enhanced MT images. Signal intensity of lesions was compared with that of the striate nucleus and white matter on contrast-enhanced MT images. True enhancement was determined by comparison with nonenhanced MT images. RESULTS: In all, 143 lesions, including 86 enhancing and 57 nonenhancing lesions, were identified among 63 patients. Almost all (99%) of the enhancing lesions were hyperintense to striate nucleus on contrast-enhanced MT images, and most (>87%) showed moderate to marked signal intensity increase from nonenhanced T1-weighted images to contrast-enhanced MT images. Most (>95%) of the nonenhancing lesions showed mild or no increase in relative signal intensity, and most (75%) were iso- or hypointense to striate nucleus on contrast-enhanced MT images. A few nonenhancing lesions (4%-6%), however, showed increase in signal intensity that was indistinguishable from true enhancement without comparison to non-enhanced MT images. CONCLUSION: Nonenhanced MT images should be obtained to assess pathologic enhancement accurately.     

Diagnostic performance of MRI for detection of intestinal fistulas in patients with complicated inflammatory bowel conditions

The diagnostic performance of magnetic resonance imaging (MRI) for detection of intestinal fistulas, other than perianal, in patients with known complicated inflammatory bowel conditions (CIBC) was investigated. Our study group consisted of 20 patients (12 women, mean age 43 years) with CIBC, including Crohn’s disease (n=13), colonic diverticulitis (n=3), colitis after radiotherapy (n=3) and of postoperative origin (n=1). Eleven surgically proven enteral fistulas were known in ten (50%) of these patients, being of enterovesical (n=3), enterocolic (n=2), enteroenteral (n=2), rectovaginal (n=2), rectovaginovesical (n=1) and of entercutaneous (n=1) localisation. The other ten patients (50%), used as the control group, showed MR features of CIBC, although without any fistulous tract. Multiplanar T1- and T2-weighted sequences had been performed, including gadolinium-enhanced acquisition with fat saturation (1.5 T). MR findings were independently blindly and retrospectively reviewed by three radiologists for the presence and etiology of any fistula, as well as visualization and characterization of the fistulous tract. Results were compared with surgical findings (n=16) and clinical evolution (n=4). Interobserver agreement was calculated. Interobserver agreement kappa for fistula detection was 0.71. Overall sensitivity, specificity and accuracy for fistula detection were 78.6%, 75% and 77.2%, respectively. Sensitivity for fistula characterization was 80.6%, with visualization of the fistulous tract in all cases, whereby T1-weighted gadolinium-enhanced fat-saturated images were considered the most useful sequences. Gadolinium-enhanced MRI is a reliable and reproducible tool for detection of enteral fistulas secondary to inflammatory conditions.     

Autogenous osteochondral ”plug” transfer for the treatment of focal chondral defects: postoperative MR appearance with clinical correlation

Objective: To describe the MR appearance following autogenous osteochondral ”plug” transfer for the treatment of focal chondral defects of the knee. Design and patients: Twenty-nine 1.5-T MR knee studies including dynamic gadolinium enhancement were performed on 21 patients following autogenous osteochondral ”plug” transfer. Three musculoskeletal radiologists retrospectively reviewed images to evaluate graft and donor site appearance and MR findings were correlated with clinical outcomes. Results: MR images demonstrated graft protuberance (n=12/21; range 1–2 mm), depression (n=2/21; range 1 mm), and surface incongruity: mild (n=17/21), moderate (n=2/21), marked (n=1/21). The T2 signal of graft cartilage was similar to that of adjacent cartilage in 25 of 29 examinations, and increased in four. Graft cartilage thickness relative to adjacent cartilage was <50% in six patients, 50–100% in 15. Graft enhancement in bone was absent at 2 weeks, but present at between 4 and 6 weeks following surgery. All patients had clinical follow-up examinations and knee outcome survey scores were obtained in 15 patients with follow-up greater than 3 months after surgery. All patients demonstrated the expected short-term progressive clinical improvement. Conclusion: MR images reveal a wide range of appearances following osteochondral ”plug” transfer. Minor variations in graft orientation and surface congruity do not result in adverse clinical outcome in the short term. Received: 8 January 2001 Revision requested: 21 February 2001 Revision received: 6 March 2001 Accepted: 6 March 2001     

The plantar fasciotomy: MR imaging findings in asymptomatic volunteers

Objective. To determine the postoperative appearance of the plantar fascia on MR imaging after a fasciotomy has been performed, and to compare the postsurgical appearance of the fascia after an open and endoscopic procedure.<@head-abs-p1.lf>Design and patients. Fifteen asymptomatic volunteers (12 women, 3 men; age range 22–49 years, mean age 33 years) with prior fasciotomies for treatment of longstanding plantar fasciitis were studied. Fourteen volunteers had a unilateral release and one volunteer had bilateral releases, allowing for assessment of 16 ankles. Eight fasciotomies were performed through an open incision and eight were performed endoscopically. The average time between surgery and imaging was 24 months (range 11–46 months). The site of surgery was established from the operative reports. Proton density (PD)-weighted and T2-weighted images in three orthogonal planes were obtained on a 1.5-T magnet. In eight studies, T1-weighted sagittal and STIR sagittal images were included. The fascia in each ankle was assessed for morphology and signal intensity. Perifascial soft tissues and bone marrow were assessed for edema. Preoperative MR studies were available in five volunteers.<@head-abs-p1.lf>Results. There was no apparent difference in the postoperative appearance of the ankle after an open or endoscopic procedure except for scar formation in the subcutaneous fat which was common after an open procedure (P<0.05). Three ankles had a gap in the fascia (one open, two endoscopic). The plantar fascia measured a mean of 7.0 mm (range 5–10 mm) at the fasciotomy, and 8.3 mm (range 6–12 mm) at the enthesis. At the fasciotomy, 11 of 13 ankles had an indistinct deep contour and 9 of 13 had an indistinct superficial contour. At the enthesis, 13 of 16 ankles had an indistinct deep contour and 6 of 16 had an indistinct superficial contour. Compared with preoperative MR studies there was an average reduction in the fascial thickness at the enthesis of 14% (range 9–20%), but the thickness at the fasciotomy nearly doubled. No edema was evident in the fascia, perifascial tissues, deep plantar muscles, or calcaneal bone marrow.<@head-abs-p1.lf>Conclusions. The average thickness of the plantar fascia in asymptomatic volunteers after surgery is nearly 2–3 times that of normal. While there is increased thickness at the site of surgery, the changes in morphology and signal intensity were most prominent at the enthesis. The key observation was absence of edema in the fascia and perifascial soft tissues. This baseline information may be of value when assessing MR studies of symptomatic patients. Received: 23 March 1999 Revision requested: 19 May 1999 Revision received: 4 June 1999 Accepted: 9 June 1999     

Age-related signal intensity changes in the corpus callosum: assessment with three orthogonal FLAIR images

The presence of age-related hyperintensities of the corpus callosum has not been thoroughly evaluated. Fifty-two patients of 50 years of age or older (mean, 71 years; range, 50–87 years) were included in this study. Fluid-attenuated inversion recovery images were obtained in three orthogonal planes. Periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs) were graded according to Fazekas rating scale. Correlations between the presence of hyperintensities in the corpus callosum and age, and the grade of PVH and DWMH were statistically analyzed. PVH was categorized as grade 0 (n=4), grade 1 (n=28), grade 2 (n=10), or grade 3 (n=10). DWMH was categorized as grade 0 (n=4), grade 1 (n=25), grade 2 (n=8), or grade 3 (n=15). Hyperintensity was considered present in the corpus callosum in 31 of the 52 patients (60%). In these 31 patients, PVH was categorized as grade 1 (n=16), grade 2 (n=7), or grade 3 (n=8), while DWMH was categorized as grade 0 (n=1), grade 1 (n=10), grade 2 (n=7), or grade 3 (n=13). The presence of callosal hyperintensities was significantly correlated with age (p=0.001), and with PVH (p=0.04) and DWMH grades (p=0.004). Hyperintensities may be present in the corpus callosum with aging, and are correlated with PVH and DWMH.     

Prevalence of muscle injury following intra-arterial chemotherapy

 Objective. Intra-arterial chemotherapy (IAC) is frequently used as an adjuvant treatment for musculoskeletal tumors. Past studies have noted that IAC not only induces favorable effects in tumor, but may also cause muscle edema and necrosis in previously normal tissue, reflected as increased signal on T2-weighted scans. In order to evaluate the prevalence of these effects, we reviewed all patients receiving IAC and MRI at our institution. Methods. Our study population consisted of 24 patients who underwent IAC. All subjects were studied with MRI both pre-and post-IAC. None of the subjects in this study underwent surgery or radiation therapy until after the post-IAC MRI examination. Any muscle group involved by the tumor or peritumoral edema on the initial scan was excluded from the study. Catheter position during IAC was recorded as central or peripheral. Scans were scored positive if muscle groups in regions remote from the tumor site demonstrated increased T2 signal following IAC. Results. Six out of these 24 patients (25%) were found to have positive results. A significant association was found between peripheral catheter position and a positive scan post-IAC (Fisher’s exact test, P=0.024). Conclusion. Because of our exclusion criteria, we are convinced that the finding of increased T2 signal in 25% of our patients was caused by IAC and represents muscle edema or necrosis. Knowledge of this post-chemotherapy MR finding should help prevent confusion during the interpretation of follow-up MR examinations.     

Emergency MRI of acute pelvic pain: MR protocol with no oral contrast

The aim of this study was to evaluate the efficacy of magnetic resonance (MR) without oral contrast in the assessment of suspected acute pathologies of the pelvis in pregnant and non-pregnant patients. Sixty-seven patients who had MR of the lower abdomen and pelvis for acute abdomen were included in the study. The MR examinations were evaluated for indication of the study, type of MR sequences, and sensitivity of MR in diagnosing the disease. T2 single shot fast spin echo (SS-FSE), T2 FSE, short tau inversion recovery, pre-gadolinium T1, and post-gadolinium T1 sequences were utilized. There were 30 pregnant and two postpartum women in the study group. Positive pelvic MR findings were seen in 73% (49/67). Final diagnoses were acute appendicitis (n = 12), ovarian torsion (n = 6), abscess (n = 3), tubo-ovarian abscess (n = 2), ovarian tumor (n = 2), degenerating fibroid (n = 3), and perianal fistula (n = 2). For acute appendicitis, sensitivity was 100% (12/12), and positive predictive value was 92% (12/13). Post-gadolinium T1-weighted sequences and T2 SS-FSE with FS were the sequences, which were most likely to best demonstrate the acute appendicitis. For ovarian torsion, the sensitivity was 86% (6/7), and positive predictive value was 100% (6/6). MR imaging is an efficacious means of diagnosing acute appendicitis, ovarian torsions, and other adnexal diseases in the acute setting. The four sequence protocol without oral contrast offers an excellent means of investigating the cause of acute lower abdominal and pelvic pain.     

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.     

Mangafodipir trisodium-enhanced MR imaging of pancreatic disease

Our study aimed to assess the diagnostic capabilities of mangafodipir trisodium-enhanced MRI for the evaluation of pancreatic disease. Sixty-three patients suspected of having pancreatic disease underwent MRI with a 1.5-T device. After the acquisition of axial and coronal T2-weighted sequences, the MR protocol included T1-weighted fat-suppressed breath-hold SPGR images obtained before and 30 min after the infusion of Mn-DPDP (Teslascan). The detection of a focal pancreatic lesion and its intensity were evaluated in consensus by two observers, who also attempted to characterize each lesion as benign or malignant. The reviewers were blinded to patient identification and all clinical, laboratory and previous imaging findings. MR imaging results were correlated with surgery (n=37), laparoscopy (n=1), biopsy (n=2) and imaging follow–up (n=22). Sixty-two subjects were effectively included in our analysis because one patient was lost to follow-up; final malignant and benign diagnoses were determined in 22 (35%) and 29 (47%) of the patients, respectively. The level of confidence in the diagnosis of the pancreatic lesion was significantly increased by the administration of Mn-DPDP as demonstrated by ROC analysis of unenhanced and post-contrast image sets (P=0.009). Overall, on the basis of observers’ readings, MR assessment of pancreatic disease resulted in 57 correct diagnoses (accuracy, 92%) and five (8%) incorrect diagnoses. The sensitivity, specificity, positive predictive value and negative predictive value of the reviewers for the detection of pancreatic lesions and for the differentiation between benign and malignant masses were 91% (95% CI: 84 and 98%), 93% (95% CI: 86 and 99%), 87% (95% CI: 79 and 95%) and 95% (95% CI: 89 and 100%), respectively. Mn-DPDP-enhanced MRI is an effective diagnostic tool for evaluating pancreatic disease.     

Role of FIESTA combined with conventional MRI in the evaluation of traumatic brachial plexus roots injury

Purpose

Purpose was to evaluate the role of Fast imaging employing steady-state acquisition (FIESTA) together with conventional MR sequences in the evaluation of traumatic brachial plexus roots injury compared to post contrast MR and Spin Echo MR myelographic studies.

Patients and methods

In this prospective study, 16 patients with a mean age of 17.9 y who presented with traumatic brachial plexus roots injury in motor cycle and car accidents were studied with FIESTA, conventional MR, post contrast MR and MR myelography sequences. Imaging findings included: pseudo-meningocele/hemorrhage near the nerve root exit, failure of visualization of the nerve root (dorsal, ventral or both), retracted avulsed nerve root ends, spinal cord edema, and para spinal muscles edema and hemorrhage. Diagnostic accuracy was calculated for each MR sequence. Imaging findings were compared with the gold standard operative findings.

Results

FIESTA combined with conventional MR depicted pseudomeningoceles, non visualized nerve roots, cord displacement, and para spinal muscles abnormalities in 15 patients (93.8%), cord edema in four patients (25%). Pre and post contrast MR detected pseudomeningoceles and non visualized nerve roots in 13 patients (81.3%) while Spin Echo myelography detected pseudomeningoceles and non visualized nerve roots in 14 patients (87.5%). FIESTA combined with conventional MR showed the highest diagnostic accuracy (93.8%) compared to pre and post MR (81.3%) and Spin Echo myelography (87.5%).

Conclusion

It is crucial to differentiate between preganglionic and postganglionic injuries for optimal treatment planning in patients with BPI. Conventional MR imaging yielded suboptimal information regarding the fine details of nerve roots’ injury. MR myelography showed some artifacts that decreased overall diagnostic accuracy, FIESTA combined with conventional MR depicted nerve segments in greater detail and provided important information about the relationship of the nerves to nearby structures, it provided high contrast resolution between cerebrospinal fluid and solid structures, allowing the reconstruction of elegant multi-planar images that highlight the injured nerves. Contrast study is recommended in mild trauma cases with normal morphological study.     

Posttraumatic pseudolipoma: MRI appearances

The goal of this study was to describe the MRI characteristics of posttraumatic pseudolipomas. Ten patients with previous history of blunt trauma or local surgery were investigated with MRI at the level of their deformity. The etiology was blunt trauma in eight patients and postoperative trauma in two. For all patients medical documentation, in the form of clinical history and physical examination, confirmed that a visible hematoma was present acutely at the same location following the injury and that the contour deformity subsequently appeared. All patients underwent liposuction. Preoperative bilateral MRI examinations were performed on all patients. The mean clinical follow-up was 17.8 months. MRI examinations were interpreted in consensus by two experienced musculoskeletal radiologists with attention to fatty extension (subcutaneous fatty thickness and anatomical extension), asymmetry compared with the asymptomatic side, the presence or absence of fibrous septae or nonfatty components, and patterns of contrast enhancement. Ten posttraumatic pseudolipomas were identified. Clinically, they showed as subcutaneous masses with the consistency of normal adipose tissue. Their locations were the abdomen (n=1), hip (n=1), the upper thigh (n=6), the knee (n=1), and the ankle (n=1). On MRI examinations, using the contralateral side as a control, pseudolipomas appeared as focal fatty masses without a capsule or contrast enhancement. Posttraumatic pseudolipomas may develop at a site of blunt trauma or surgical procedures often antedated by a soft tissue hematoma. Characteristic MRI findings are unencapsulated subcutaneous fatty masses without contrast enhancement.     

Incidence and MR imaging features of fractures of the anterior process of calcaneus in a consecutive patient population with ankle and foot symptoms

Objective To determine the incidence, appearances and associated injuries of fractures affecting the anterior process of calcaneus from a general population with foot and ankle symptoms.Design and patients A retrospective review of foot and ankle MR imaging procedures was performed for detection of cases with a fracture affecting the anterior process of calcaneus over a four year period. Radiographs, MR imaging studies, radiology reports, medical records, and operative notes were reviewed. Imaging analysis included fracture pattern, displacement, associated fractures, and presence of tendon and ligamentous injuries.Results The incidence of anterior process of calcaneus fracture on MR imaging was 0.5% (14/2577). Fractures were more common in female subjects (71%, 10/14). Fracture orientation was predominantly vertical (93%, 13/14). No comminuted fractures were seen and only three fractures were displaced. Three of the eight MR imaging evident fractures of anterior process of calcaneus were seen on radiographs. Associated fractures of the talus (n=5), navicular bone (n=3), cuboid (n=2), and calcaneal body (n=1) were noted. Associated injuries to the anterior talofibular ligament (n=3) and tears of the peroneus brevis (n=3) and peroneus longus (n=1) tendons were present. All fractures were treated non-operatively. Two patients had subtalar joint steroid injection for symptomatic relief.Conclusions Fractures of the anterior process of the calcaneus are uncommon in MR examinations of a general population of patients with foot and ankle symptoms. Although anterior process of calcaneus fractures are rare, there was a moderately high incidence of associated bone and soft-tissue injuries.