Fat-suppressed T2-weighted Images Research Articles

Magnetic resonance imaging features of multiple duodenal lipomas: a rare cause of intestinal obstruction

A 65-year-old man was evaluated because of vomiting and epigastric pain. The patient underwent upper gastrointestinal endoscopy and endoscopic ultrasound examination and was found to have multiple polypoid lesions in the D1 and D2 portions of the duodenum, causing almost complete obstruction of the duodenal lumen. The lesions were hyperintense on T1-weighted and intermediately intense on T2-weighted images, with a drop in signal on T1- and T2-weighted fat-suppressed images, consistent with a diagnosis of duodenal lipomas. Pathohistological examination confirmed the diagnosis of duodenal lipomas.

Experimental Study of Artificially Induced Intramuscular Gossypiboma in Rabbits: Correlation of Sequential MRI Findings With Pathologic Findings

The purpose of this study was to evaluate the sequential MRI findings of intramuscular gossypiboma and to correlate them with the pathologic findings in rabbits. Sterile gauze was packed in the hamstring muscles of 12 rabbits, and sequential MR images were obtained 1, 2, and 4 weeks and 2, 6, and 12 months after gauze insertion. Two rabbits were sacrificed at each time point. Their pathologic findings were compared with the MRI findings on each date. At the acute stage, the gossypibomas appeared as areas of heterogeneous low signal intensity on T2-weighted MR images with inflammatory change around the gossypiboma. In the subacute stage, the gossypibomas appeared as areas of peripheral low and central high signal intensity with wavy stripes of low signal intensity on T2-weighted images. On contrast-enhanced fat-suppressed T1-weighted images, the peripheral enhancement of the masses advanced toward the center of the mass as the fibrocollagenization between the gauze bundles progressed centrally. In the chronic stage, on contrast-enhanced fat-suppressed T1-weighted images, central advancement of the peripheral enhancement occurred according to the maturation of the fibrocollagenization. Calcifications around individual gauze fibers were observed 6-12 months after gauze insertion. On sequential contrast-enhanced fat-suppressed T1-weighted images of rabbits, intramuscular gossypiboma exhibited a chronologic centripetal enhancement pattern for 1 year mainly owing to concentric progression of fibrocollagenization between gauze bundles toward the center of the mass.

Subacute progressive ophthalmoplegia associated with dermatomyositis

Dermatomyositis is a systemic autoimmune disorder that primarily affects the skin and skeletal muscle in the extremities, and is characterized by weakness of the proximal groups of limb muscles. Extraocular muscle involvement is a very rare manifestation of dermatomyositis [5, 8]. We herein report a patient who manifested dermatomyositis with subacute progressive ophthalmoplegia. The patient was a 53-year-old Japanese male who presented with myalgia and difficulty in climbing stairs. He developed progressive diplopia with eyelid edema and ocular pain 2 weeks after presentation, followed by difficulties in raising his arms. No autoimmune, endocrinopathy, or malignant diseases were observed. The physical examination revealed the presence of Gottron’s papules on the dorsal surface of the hands, and a neurological examination showed symmetrical weakness of the proximal muscles, including the upper limbs muscles, and bilateral ophthalmoplegia with total limitations of eye movements (Fig. 1). There was no weakness of the facial muscles or bulbar palsy. Laboratory tests revealed an increased creatine kinase (CK) level (10,808 U/l; normal range, 25–190). There was no abnormal thyroid function or serum autoantibody, including antinuclear antibody, anti-acetylcholine receptor antibody, and anti-thyroid antibodies. No malignant tumors, including thymoma or thymic hyperplasia, were observed using whole-body CT and PET imaging. Intravenous edrophonium had no effect on the ophthalmoplegia. The repetitive nerve stimulation test was normal. The muscle biopsy at the left vastus medialis muscle revealed inflammatory myopathic changes, which showed the invasion of mononuclear cells into the interfascicular septae and within the fascicles, perifascicular atrophy, and variations in the muscle fiber size. An immunohistochemical analysis showed the mononuclear cells to be CD4and CD8-positive lymphocytes. Ragged red fiber or cytochrome c oxidase-negative fibers were absent. The patient was treated with 60 mg/day oral prednisolone. His ocular impairment, weakness of the proximal muscles, and elevated CK values became markedly improved 1 month after the steroid therapy. Orbital magnetic resonance imaging (MRI) scans revealed an increased thickness of the extraocular muscles on T1-weighted images (Fig. 2a) and high-intensity signals of the extraocular muscles on fat-suppressed T2-weighted images (Fig. 2c), which were both improved after the steroid therapy (Fig. 2b, d). No myositis-associated autoantibodies, including anti Jo-1, PM-Scl-100, PL-7, PL-12, EJ, OJ, KS, M2, Ku (p70/80), SRP, Rib-P antibodies and the antimitochondrial antibody of M2 subtype, were detectable in the serum. Previous reports have suggested that the ophthalmoplegia observed in inflammatory myopathies is caused by the S. Kono (&) T. Bunai T. Konishi K. Shirakawa H. Miyajima First Department of Medicine, Hamamatsu University School of Medicine, 1-20-1, Handayama, Hamamatsu 431-3192, Japan e-mail: satokono@hama-med.ac.jp

Abstract 2572: Dual Imaging with MRI and 18 F-FDG PET Can Highly Predict Lipid and Hematoma in Carotid Plaque

Background and Purpose - Recent studies have disclosed that inflamed and vulnerable plaques in the carotid artery are at high risk for subsequent ischemic stroke, suggesting the importance of non-invasive diagnostic modalities with high sensitivity and specificity to detect them in patients with carotid artery stenosis. Although many investigators have reported that MR imaging is a useful tool to predict the components of carotid plaque, its validity is not established. On the other hand, 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) may be an alternative modality to directly identify the inflamed plaque in carotid artery stenosis. Therefore, this study was aimed to evaluate the validity of MR imaging and 18 F-FDG PET to predict the components of carotid plaques. Methods - Totally 19 patients were included in this study. Prior to carotid endarterectomy (CEA), 18 F-FDG PET, black-blood fat-suppressed T1-weighted (FS-T1) imaging, and 3-dimensional time-of-flight (TOF) imaging were performed in all of them. During CEA, macroscopic observation of carotid plaque was performed under surgical microscope. The specimens were stained with primary antibodies against CD68 and MMP9. Results - 18 F-FDG PET revealed that 11 of 19 patients had the carotid plaque with significantly high 18 F-FDG uptake (SUVmax >2.0). All of them had lipid-rich soft plaque with strong immunoreactivity against CD68 and MMP9. Its sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to identify lipid-rich soft plaque were all 100%. On the other hands, 6 out of 19 patients had the carotid plaque with high signal intensity on both FS-T1 and TOF imaging. Carotid plaque had a large intraplaque hematoma in these 6 patients. Their sensitivity, specificity, PPV, and NPV to identify intraplaque hematoma were 86%, 100%, 100%, and 92%, respectively. Conclusions - These findings strongly suggest that MRI and 18 F-FDG PET are complementary to predict the components of carotid plaque. The former would be useful to detect vulnerable plaque with subintimal hemorrhage, and the latter would be sensitive to identify vulnerable plaque with lipid-rich component. Therefore, combination of these two modalities may be quite valuable to non-invasively predict the carotid plaque at higher risk for subsequent ischemic stroke.

Middle cerebral artery intraplaque hemorrhage: Prevalence and Clinical Relevance

Little is known about the composition of middle cerebral artery (MCA) plaques and how they relate to clinical status. Using high-resolution magnetic resonance imaging (HR-MRI), we aimed to examine the occurrence of high signal on T1-weighted fat-suppressed images (HST1) of MCA plaques, which are highly suggestive of fresh or recent intraplaque hemorrhage. We retrospectively analyzed the HR-MRI and clinical data of 107 adult patients with high-grade (>70%) MCA stenosis. On HR-MRI, HST1 within an MCA plaque was defined as an area with an intensity >150% of the signal of adjacent muscles. The relationship between HST1 and clinical presentations was analyzed. A total of 109 stenotic MCAs (46 symptomatic and 63 asymptomatic) on 981 image slices were analyzed. HST1 was revealed on HR-MRI in 11 vessels (10.1%, 9 symptomatic and 2 asymptomatic). The occurrence rate of HST1 between symptomatic and asymptomatic MCAs was significantly different (19.6% vs 3.2%, p = 0.01). HST1 within MCA plaque on HR-MRI is associated with ipsilateral stroke. Our results provide new insight into the vascular biology of MCA atherosclerosis.

Infrapatellar plica of the knee: Revisited with MR arthrographies undertaken in the knee flexion position mimicking operative arthroscopic posture

PurposeTo describe the appearance of the infrapatellar plica (IPP) on magnetic resonance arthrography (MRA) taken in 70° knee flexion, corresponding to the arthroscopic posture. Materials and methodsTwenty-two patients (23 knee joints) who underwent MRA with 70° knee flexion were enrolled. All patients underwent MRA with 70° knee flexion to simulate operative arthroscopy. The images included fat-suppressed T1-weighted spin echo axial, sagittal, and coronal images. The visualization and morphology of the IPP were retrospectively assessed by two musculoskeletal radiologists. ResultsThe IPP was demonstrated in 78.3% (n=18/23) and was best visualized on the sagittal section through the intercondylar notch. The IPP manifested as a linear hypointense structure with variable thicknesses. The intercondylar component was delineated clearly, arising from the anterior intercondylar notch in parallel with the ACL and curving gently downward to attach to the infrapatellar fat pad. On the other hand, the Hoffa's fat pad component was not depicted clearly. The morphology of the IPP was either a separate type (60.9%) or a split type (17.4%). ConclusionThe IPPs can be visualized with a high rate of detection and various morphologic appearances must be appreciated under the review of a flexed knee MRA.

Characteristic magnetic resonance features of focal autoimmune pancreatitis useful for differentiation from pancreatic cancer

To identify characteristic magnetic resonance (MR) features of focal autoimmune pancreatitis (f-AIP) useful for differentiation from pancreatic cancer (PC). We retrospectively analyzed MR imaging findings of 20 f-AIP lesions and 40 PC lesions smaller than 40 mm in diameter. On fat-suppressed T2-weighted images and dynamic contrast-enhanced fat-suppressed T1-weighted images (DCE-T1WI), we classified MR features of internal signal intensity for each lesion into homogeneous, speckled, or target type. We assessed the sensitivity, specificity, and accuracy of these findings in the diagnosis of f-AIP. We also investigated the incidence of previously reported findings for differentiation between f-AIP and PC. Speckled enhancement within a hypointense or isointense lesion on pancreatic phase DCE-T1WI (speckled type) was observed more frequently in f-AIP than in PC, with high sensitivity, high specificity, and high accuracy. Hypointensity to hyperintensity surrounding a less enhanced focal area on DCE-T1WIs (target type) and upper stream main pancreatic duct dilatation were observed more frequently in PC than in f-AIP. Speckled enhancement inside an f-AIP lesion on pancreatic phase DCE-T1WI was useful for differentiation from PC.

The role of breast MR imaging in pre-operative determination of invasive disease for ductal carcinoma in situ diagnosed by needle biopsy

To evaluate whether magnetic resonance (MR) imaging features can predict the presence of occult invasion in cases of biopsy-proven pure ductal carcinoma in situ (DCIS). We retrospectively reviewed 92 biopsy-proven pure DCIS in 92 women who underwent MR imaging. The following MR imaging findings were compared between confirmed DCIS and invasive breast cancer (IBC): lesion size, type, morphological and kinetic assessments by ACR BI-RADS MRI, and findings of fat-suppressed T2-weighted (FS-T2W) imaging. Sixty-eight of 92 (74%) were non-mass-like enhancements (NMLE) and 24 were mass lesions on MR imaging. Twenty-one of 68 (31%) NMLE and 13 of 24 (54%) mass lesions were confirmed as IBC. In NMLE lesions, large lesions (P = 0.007) and higher signal intensities (SI) on FS-T2W images (P = 0.032) were significantly associated with IBC. Lesion size remained a significant independent predictor of invasion in multivariate analysis (P = 0.032), and combined with FS-T2W SIs showed slightly higher observer performances (area under the curve, AUC, 0.71) than lesion size alone (AUC 0.68). There were no useful findings that enabled the differentiation of mass-type lesions. Breast MR imaging is potentially useful to predict the presence of occult invasion in biopsy-proven DCIS with NMLE. MR mammography permits more precise lesion assessment including ductal carcinoma in situ A correct diagnosis of occult invasion before treatment is important for clinicians This study showed the potential of MR mammography to diagnose occult invasion Treatment and/or aggressive biopsy can be given with greater confidence MR mammography can lead to more appropriate management of patients.

Magnetic resonance imaging (MRI) detection of synovitis and bone lesions of the wrists and finger joints in early-stage rheumatoid arthritis: comparison of the accuracy of plain MRI-based findings and gadolinium-diethylenetriamine pentaacetic acid-enhanced MRI-based findings

To explore whether synovitis and bone lesions in the wrists and finger joints visualized by plain magnetic resonance imaging (MRI)-based findings correspond exactly or not to those judged by gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced MRI-based findings. Magnetic resonance imaging of the wrists and finger joints of both hands were examined in 51 early-stage rheumatoid arthritis (RA) patients whose median disease duration from the onset of articular manifestations to entry was 5 months, by both plain (T1 and short-time inversion recovery images) and Gd-DTPA-enhanced MRI (post-contrast fat-suppressed T1-weighted images) simultaneously. We focused on 15 sites per hand, to examine the presence of synovitis and bone lesions (bone edema and bone erosion). Gd-DTPA-enhanced MRI-based findings were considered "true" lesions, and we evaluated the accuracy of plain MRI-based findings in comparison to Gd-DTPA-enhanced MRI-based findings. Synovitis, judged by plain MRI-based findings, appeared as false-positive at pretty frequency; thus, the specificity, positive predictive value and accuracy of the findings were low. The rate of enhancement (E-rate) in false-positive synovitis sites was significantly low compared with true-positive synovitis sites where Gd-DTPA enhancement appears. In contrast to synovitis, the false-positivity of bone lesions, judged by plain MRI-based findings, was very low compared with Gd-DTPA-enhanced MRI-based findings. Synovitis judged by plain MRI-based findings is sometimes considered false-positive especially in sites where synovitis is mild. However, plain MRI is effective in identifying bone lesions in the wrist and finger joints in early-stage RA.

Successful First‐line Treatment With Propranolol of Multifocal Infantile Hepatic Hemangioma With High‐flow Cardiac Overload

Successful First‐line Treatment With Propranolol of Multifocal Infantile Hepatic Hemangioma With High‐flow Cardiac Overload

1H-magnetic resonance spectroscopy of the breast at 3.0-T: Comparison of results obtained before and after administration of gadolinium-based contrast agent

To assess the effects of gadolinium-based contrast agent (GBCA) on (1) H-magnetic resonance spectroscopy (MRS) of the breast at 3.0-T. Patients (n = 98) with breast cancer (98 lesions) underwent MRS (point-resolved spectroscopy sequence [PRESS]; TR/TE, 2000/100 msec; voxel size, 15 × 15 × 15 mm) before the administration of GBCA. In 52 of those patients, MRS was also performed after the administration of GBCA. The voxel-of-interest (VOI) was placed by referring to the noncontrast-enhanced MRI (diffusion-weighted images combined with fat-suppressed T2-weighted images). We reviewed and graded the appropriateness of VOI location compared to the correlating enhancement lesions. Integral values of the choline peak at a frequency of 3.2 ppm on MRS were compared before and after the administration of GBCA. The VOI was placed correctly in 64 lesions (65%), although the VOI was placed outside the targeted lesion in 34 lesions (35%). The integral value of the choline peak on MRS decreased significantly after the administration of GBCA (P < 0.001). Accumulation of GBCA in breast cancer could affect the choline peak on MRS. MRS of breast cancer at 3.0-T can be recommended to be acquired before contrast-enhanced study; however, some problems remain in VOI placement with reference to the noncontrast-enhanced study.

Uterine perforation with omentum incarceration after dilatation and evacuation/curettage: magnetic resonance imaging findings

Cervical dilatation and/or uterine evacuation and curettage (D/E&C) is the most commonly performed and safest gynecological procedure. Although procedure-related uterine perforation is rare, this condition may require surgical intervention. Ultrasound examination and computed tomography are useful for diagnosing such perforations with incarceration of an intra-abdominal organ. However, the use of magnetic resonance imaging (MRI) for detecting postabortal uterine damage has seldom been discussed in the literature. A 31-year-old woman was referred to our department for lower abdominal pain and a small amount of vaginal bleeding 28 days after D/E&C for a missed abortion. Transvaginal ultrasound examination showed the presence of a hyperechogenic structure in the anterior wall of the uterine body, which was verified to be fatty tissue by MRI, particularly on the fat-suppressed T1-weighted images. An emergency laparotomy showed a uterine perforation with omentum incarceration. After dissecting the omental loop, the uterine perforation site was incised, and the involved omental tissue was debrided appropriately. To our knowledge, this is the first report wherein MRI was used for the detection of incarcerated omental fat within the uterus. Delayed presentation of uterine perforation may be observed 1 month or more after D/E&C, although such a finding is extremely rare. Therefore, postabortal follow-up bimanual vaginal examination using transvaginal ultrasonography is recommended. The current study indicates the usefulness of MRI when myometrial perforation with or without incarceration of an extrauterine organ is suspected.

Retroportal main pancreatic duct with circumportal pancreas: radiographic visualization

Purpose The aim of this study was to investigate the imaging findings of retroportal main pancreatic duct (RMPD), a rare anomaly of the pancreas, and circumportal pancreas (CP) on computed tomography (CT) and magnetic resonance (MR) imaging. We also reviewed the previous literature and discussed its best imaging method, etiology and clinical importance. Methods This work is a retrospective study. Two cases of RMPD were enrolled. The imaging findings of RMPD and CP were reviewed among the various CT and MR images obtained. Differences in visualization among the scans were evaluated using a four-stage model. Results RMPD was always accompanied by CP. RMPD was detectable on contrast-enhanced CT but not on noncontrasted CT. RMPD was shown most clearly on arterial, portal and late phases of contrast-enhanced CT, contrast-enhanced fat-suppressed T1-weighted images and fat-suppressed T2-weighted images. CP was much easier to detect than RMPD and could be identified even on noncontrasted images. Conclusions We described the fourth and the fifth reported cases of RMPD. This is the first study to describe its MR imaging findings. CP was always present in cases of RMPD and was easily detectable on tomographic images. When radiologists or surgeons notice CP, it is necessary to pay attention to the course of the main pancreatic duct, particularly preoperatively to avoid surgical complications. It should be noted that these anomalies are undetectable on projection images.

MRI manifestations of bone marrow changes after recombinant human granulocyte colony stimulating factor was subcutaneous injected for healthy adults

Objective To investigate MRI manifestations of lumbar and proximal femoral bone marrow changes before and after recombinant human granulocyte colony stimulating factor (rhG-CSF) was subcutaneous injected for healthy adults. Methods Twenty healthy blood stem cell donors without hematologic disease were enrolled in this study. All of them underwent lumbar sagittal and proximal femur coronal MRI examination with spin echo T1 WI and fat-suppressed T2WI. The first examination were performed before subcutaneous injection of rhG-CSF for comparison. In 4-7 days and 30-60 days after injection, the other two examinations were performed. The signal changes of lumbar and proximal femoral bone marrow were investigated by reading pictures and calculating the contrasted noise ratio (CNR).Results Before rhG-CSF injection, all patients presented normal signal intensity of hone marrow. In 4-7 days after injection, all the 20 cases presented homogeneous signal decrease in lumbar vertebral bodys on T1 WI, accompanied by reduced fatty signal. In proximal femur, patchy or stripped hypointensity areas were found in intertrochanteric and subtrochanteric areas on T1 WI. On fat-suppressed T2 WI images, the signal of lumbar and proximal femoral bone marrow changed to equal or slightly-high signal intensity. In all cases,abnormal signal areas presented in lumbar and proximal femoral bone marrow occurred simultaneously in the same case. In the 10 cases received the third MRI during 30-60 days after rhG-CSF injection, signal intensity of lumbar bone marrow turned to normal in all sequence, but abnormal signal intensity areas were still existed and extended to distal part in femoral bone marrow, which appeared as symmetric stripped or patchy equal or slightly-low signal intensity on T1 WI and equal or slightly-high signal intensity on T2 WI. The CNR of lumbar bone marrow to subcutaneous fat before rhG-CSF injection, in 4-7 days and 30-60 days after rhG-CSF injection were 114. 11 ± 15. 11,71.04 ± 12. 25 and 91.64 ± 1 I. 68, respectively. Significant difference was found between before rhG-CSF injection and 4-7 days after injection ( P ＜ 0. 05 ) , but no significant difference between the others( P ＞ 0. 05 ). Conclusion After injection of rhG-CSF, the short-term changes of hematopoietic cells and fat content in bone marrow can be displayed on MRI, which provided non-invasive information for bone marrow transplantation. Key words: Stem cell transplantation; Bone marrow; Magnetic resonance imaging

Comparison of MRI manifestations and histopathologic findings of the elderly carotid arteries in ex vivo

Objective To evaluate the ability of high resolution magnetic resonance (MR) imaging at 3.0 tesla to depict the characterization of human carotid arterial vessel wall and detect atherosclerotic lesions ex vivo in comparison to histopathologic results. Methods Eighteen carotid arteries obtained from 9 elderly donors underwent fat-suppressed T1 - and T2-weighted MR imaging at 3.0 tesla MR system with a mouse coil. Corresponding histological sections were obtained for the comparison. Correlation between MR images and histopathologic slices was obtained by Pearson or Spearman correlation coefficient. Cohen K was computed to quantify the agreement between MRI and histopathologic findings. Results Lumen area,intima and media area measured on fat-suppressed T2-weighted images showed stronger correlation with the corresponding histopathologic slices [ MRI vs. histopathology: ( 27. 53 ± 6. 77 ) mm2 vs. ( 25.83 ±6. 69 ) mm2, r2 ＝ 0. 91,P2 ＝ 0. 024, ( 12.31 ± 3. 31 ) mm2 vs. ( 12. 28 ± 3.71 ) mm2, r2 ＝ 0. 70, P2 ＝ 0. 020,Median 12. 29 mm2(Min 1.12 mm2, Max 33.18 mm2) vs. Median 11.62 mm2(Min 0.89 mm2, Max 32. 84 mm2 ), r2 ＝ 0. 74, P2 ＝ 0. 016, respectively]. The Cohen K score between the MR imaging and American Heart Association classifications was 0. 74, which corresponds to a good agreement. Conclusions 3.0 T high-resolution multi-sequence MRI can clearly show the structure of ex vivo carotid artery wall and allow quantitative assessment. Fat-suppressed T2W imaging has a greater advantage in presenting atherosclerotic lesions. Key words: Carotid artery diseases ; Atherosclerosis; Magnetic resonance imaging

The iliac wing sign: An indicator of the presence of bone and/or soft-tissue injury of the pelvis and hips

PurposeTo prospectively evaluate the feasibility of using the “iliac wing sign (IWS)” as an indicator of bone and/or soft-tissue injury of the pelvis and hips on magnetic resonance (MR) imaging. IWS means edema of the iliacus muscle attachment entering the iliac wing that is visualized as a linear high signal intensity on fat-suppressed T2-weighted MR images. MethodsConsecutive 106 patients who complained of hip pain were enrolled in this study. We evaluated the correlation between IWS and bone and/or soft-tissue injury of the pelvis and hips using Fisher's exact test. Further, performance parameters of sensitivity, specificity, accuracy, the positive predictive value (PPV), and negative predictive value (NPV) of IWS were calculated. ResultsThirty-eight of the 106 (36%) patients had bone and/or soft-tissue injury. Twenty-seven of these 38 (71%) patients with injury showed a positive IWS, while only 11 of 68 (16%) patients without injury showed a positive IWS (p<.0001). IWS, thus, yielded a sensitivity of 71%, specificity of 84%, accuracy of 79%, positive predictive value (PPV) of 71%, and negative predictive value (NPV) of 84%. ConclusionIn cases with a positive IWS, the careful interpretation of MR images is needed because injury presence is highly likely, as suggested by the relatively high sensitivity and PPV. IWS absence may mean a low probability of injury because of the high specificity and NPV.

Chondromyxoid Fibroma of the Ethmoid Sinus

Abstract : A 43-year old Black female complained of sinus pressure and was found to have a mass of the right ethmoid sinus. A T1-weighted fat-suppressed (FS) post-clear coronal magnetic resonance imaging (MRI) study revealed right mid-level ethmoid air cells that were expanding the sinus cavity. A slightly lower density signal compared to brain was noted, at 35 Hounsfield units, and was found to be isointense with skeletal muscle. Notably, this coronal image showed that the mass was not descending from the cranial compartment, thereby effectively ruling out an encephalocele. A T1 axial FS MRI showed bone remodeling as the tumor had eroded through the lamina papyracea at the medial wall of the orbit. A fluid attenuated inversion recovery MRI indicated the absence of bright signals to indicate hemoglobin, necrosis, calcification, or proteinaceous debris. No edema was noted in the medial rectus muscle and no infiltration of fat of the orbit was identified, suggesting a non-aggressive nature to this lesion.

Le syndrome d’œdème médullaire de la tête fémorale

Transient bone marrow edema of the hip is characterized by moderate homogeneous low MR signal intensity with ill-defined margins that involves at least a portion of the femoral head. Spin echo T1-weighted images are helpful to exclude other underlying diseases (tumor, infection, necrosis from systemic origin…), for which marrow edema is secondary or no epiphyseal in location. High-resolution fat-suppressed T2-weighted or proton density images allow evaluation of the articular cartilage, subchondral bone and subchondal marrow: if the articular cartilage is abnormal, the lesion is irreversible (arthrosis or necrosis); if the subchondral bone is focally interrupted and/or if the femoral is no longer spherical, the lesion is irreversible (necrosis); if a focal linear fluid collection is present under the subchondral bone, the lesion is irreversible (necrosis). Finally, subchondral changes may provide useful prognostic information: the absence of any abnormality other than marrow edema typically indicates that complete resolution is likely; the presence of a focal T2-weighted hypointense lesion immediately next to the subchondral bone suggests an irreversible lesion, especially if it is equal to or thicker than 4mm or the joint space. In some instances, prognosis cannot be reliably determined requiring the need for follow-up imaging.

Active gastrointestinal hemorrhage identification by blood pool contrast-enhanced magnetic resonance angiography

Localization of the source of gastrointestinal hemorrhage can be challenging. Currently, this is often accomplished with tagged red blood cell scintigraphy, with attendant ionizing radiation and relatively poor spatial resolution. We describe an analogous method of detecting acute gastrointestinal hemorrhage by enhanced MRI with blood pool contrast agent. Briefly, following precontrast fat-suppressed volumetric T1-weighted image acquisition, single-dose gadofosveset trisodium, a blood pool agent, is administered. Then serial post-T1-weighted images are obtained. This technique is a novel method for evaluating gastrointestinal hemorrhage.

Pigmented Villonodular Synovitis of the Ankle

Pigmented villonodular synovitis (PVNS) of the ankle is a rare benign proliferative growth of the synovium. Studies of the radiologic characteristics of ankle PVNS are sparse. To characterize the radiologic features of ankle PVNS, five patients with histologically proven ankle PVNS were retrospectively studied. The features of their radiographs, computed tomographic scans, and magnetic resonance images were reviewed, with emphasis on the morphological features, extension, margin, bone involvement, signal intensity, and degree of magnetic resonance enhancement. All five lesions were diffuse, affecting the ankle and distal tibiofibular joint; three lesions also involved the subtalar joint. Radiography demonstrated extrinsic bone erosions with marginal sclerosis of the involved joints in all of the patients, but computed tomography identified this much better than did radiography. Magnetic resonance imaging revealed multiple lobulated soft-tissue masses in all of the cases. These soft-tissue masses surrounded the flexor hallux longus tendon and were hypointense on T1-weighted images, with a heterogeneous signal in two cases and homogenous hypointensity in three cases on fat-suppressed T2-weighted images. In one patient who underwent gadolinium-enhanced imaging, the masses showed intense enhancement. Magnetic resonance imaging is the best way to reveal ankle PVNS. Magnetic resonance imaging findings of predominant hypointensity on all pulse sequences and standard radiography findings of bone erosion with marginal sclerosis are characteristic.