Focal Low Signal Research Articles

Frequency of MRI Low Signal Intensity in the Buccal Fat of Fetuses and Speculation as to What It May Reflect.

We aimed to characterize the fetal buccal fat pad (BFP) on magnetic resonance imaging (MRI) to determine the frequency and types of sequences on which the BFP demonstrates low signal intensity and determine any possible correlation with timing of the MRI during fetal development. A retrospective review of all fetal MR studies was performed, and a pediatric radiologist blinded to the referring and final fetal diagnosis as well as outcome evaluated the included cases. A positive buccal fat pad sign (BFS) was recorded as present if a round, symmetric, and bilateral area was seen in the submalar region of the face with the following signal characteristics: T1 hyperintensity, low signal on echo planar imaging (EPI), low signal on true fast imaging with steady-state free precession (TRUFI), and with restriction on diffusion-weighted imaging (DWI). A total of one hundred sixty-seven (167) fetal MRI studies: one hundred fourteen (114) body (68%) and fifty-three (53) neuro (32%) scans were reviewed during the study period. The BFS was most commonly seen on EPI (63%) and TRUFI (49%) sequences. Substantial agreement between TRUFI and EPI (κ = 0.68; p < 0.01); moderate agreement between TRUFI and T1 (κ = 0.53; p < 0.01) as well as T1 and EPI (κ = 0.53; p < 0.01), and fair agreement between EPI and Diffusion (κ = 0.28; p < 0.01) was observed. The median gestational age (GA) was 24 weeks (IQR 22-30 weeks). The fetuses with a positive BFS were significantly older (mean GA of 27 weeks or higher) than those without, for each sequence. The focal low signal in the fetal buccal fat pad, termed the fetal BFS, is a commonly encountered normal finding in the majority of fetal MRI scans on TRUFI and EPI sequences. This finding may be related to the presence and development of brown adipose tissue in the buccal fat pad resulting in T2* effects, but further studies are needed in order to confirm this. Further work can incorporate any of the sensitive sequences demonstrating low signal in brown adipose tissue to map its distribution and development in the fetus and beyond.

Diagnosis and management of temporomandibular joint synovial chondromatosis: A systematic review

The aim of this study was to systematically review the diagnosis and management of temporomandibular joint synovial chondromatosis (TMJ-SC). Using a systematic study design based on the PRISMA guideline, the researchers implemented and analyzed a cohort of relevant publications indexed by PubMed, Embase, Medline, and LILACS between January 1990 and December 2022. The outcomes of interest were demographics of the primary studies, and Clinical, radiological, and therapeutic data associated with TMJ-SC. The study samples included 8 studies presenting 121 TMJ-SC cases (73.6% female; 100% unilateral; 53.7% left-sided; mean age, 43.3 ± SD 5,80 [range, 21–81]. Non-specific symptoms were mostly reported, including TMJ pain, noise and local inflammation, and/or malocclusion. Radiographically, loose bodies, masses with low-signal foci, and calcification were common charateristics. Until now, there has been no internationally accepted consensus on diagnosis and management of TMJ-SC. Arthroscopic surgery should be performed on masses confined to the superior TMJ space, while open arthroplasty is indicated in cases with the extra-articular extension. A combination of both treatment methods may be necessary, when the lesion locates extending beyond the medial groove of the condyle.

Imaging Features and Risk Factors of Pancreatic Cystic Lesions Complicating Autoimmune Pancreatitis: A Retrospective Study.

This study aimed to explore the imaging features and risk factors of PCLs complicating AIP, and investigate its prognosis through continuous imaging follow-up. Patients who were diagnosed with AIP from January 2014 to December 2020 in our hospital were recruited. We analyzed the CT and MRI features of PCLs complicating AIP, and investigated its prognosis through imaging follow-up. We also compared subjects with and without PCLs using clinical, laboratory, and imaging data; the related risk factors associated with PCLs were investigated in a multivariate logistic regression analysis. In this group, 16 patients had PCLs and 86 did not. A total of 43 PCLs larger than 5mm were found in 15 patients. Among these PCLs, 35 showed homogeneous signal (density); one, bleeding; three, linear separation; and four, small focal low signal on T2WI. Eight patients with 23 PCLs appeared for the follow-up after steroid treatment. Short-term follow-up showed that 11 PCLs disappeared, nine reduced, one unchanged and two enlarged. Of the 12 PCLs that did not disappear, 10 PCLs disappeared at long-term follow-up, except for two reduced PCLs were not re-examined. Logistic regression analysis showed that drinking history was an independent risk factor, age ≥ 65 years was an independent protective factor for PCLs complicating AIP. The imaging features of PCLs complicating AIP are various, which can be single or multiple, most of them are homogeneous, and some lesions may be accompanied by hemorrhage, separation and necrosis. Age ≥ 65 years and avoiding drinking may help to reduce the occurrence of these lesions.

Cerebral fat embolism: An unusual case report and literature review

BackgroundFat embolism syndrome (FES) is a rare syndrome induced by embolization of lipid droplets in the bloodstream, commonly seen after long-bone fractures or orthopedic surgery. Case presentationWe report an unusual case of cognitive impairment following a motor scooter accident for which repeated brain MRI, performed on the tenth day after trauma, showed decreased hyperintense lesions on T2-FLAIR and DWI and numerous scattered small foci of low signal in the regions in T2*-weighted (T2*WI) gradient-echo and SWI images. ConclusionWe report a case of mental deterioration after a lucid interval that illustrates the usefulness of repeating brain MRI, especially the SWI sequence, to show the classic “starfield pattern” but also a possible dynamic and extensive appearance of hypointense punctate foci suggestive of the diagnosis. We recommend actively searching for an uncommon distal bone fracture if the initial body CT scan is negative and the diagnosis of CFE is suspected.

Diagnosis and Treatment of Cerebral Syphilitic Gumma: A Report of Three Cases

Cerebral syphilitic gumma is very rare and is often pathologically confirmed following surgery. This study reports three patients with cerebral syphilitic gumma. The first case was a 62-year-old man who was admitted to our hospital due to speech arrest for 10 hours. Head MRI showed a nodular signal shadow with a significant enhancement and a significant centerline shift. He subsequently received surgery, and cerebral syphilitic gumma was confirmed by postoperative pathology. The second patient was a 66-year-old man who was admitted to our hospital due to complaints of gradually decreasing right eye vision and headache for nearly 50 days. Enhanced MRI at admission indicated irregular clumping of high-signal mixed with low-signal foci on the frontal lobe. Subsequently, he was operatively treated and was confirmed to have cerebral syphilitic gumma by postoperative pathology. The third patient was a 37-year-old man who was admitted to our hospital due to dizziness for approximately 15 days. Head MRI indicated a slightly abnormal lamellar and longer T1, T2 signal shadow on the left side. He did not receive surgery, and his symptoms disappeared after anti-syphilitic treatment. Hence, we recommend a critical interpretation of preoperative imaging data, understanding the unique changes that arise in the brain that can be detected through imaging, and an analysis of the patient history and laboratory tests to re-evaluate the value of surgery, with the ultimate goal of performing a stabilizing treatment for cerebral syphilitic gumma.

A model of acute central cervical spinal cord injury syndrome combined with chronic injury in goats.

To develop a large animal model for acute central cervical spinal cord injury syndrome (ACCSCIS. Twenty-four adult male goats were randomized into four groups including group A with acute compression injury, group B with anterior chronic compression, group C as the test group that received anterior chronic compression by screw and acute compression by posterior balloon insertion, and group D as normal controls that received sham surgery. Neurological function (modified Tarlov motor function), CT, MRI, cortical somatosensory evoked potentials (CSEP), and pathological analysis were evaluated. The data were analyzed statistically. The motor function of the goats in group C was significantly lower than other groups. CSEP before spinal cord compression showed a stable pattern. Spinal cord compression resulted in a gradual decrement in the peak latency and significant increment in the peak amplitude. Cervical spinal canal occupying ratio was significantly lower in group C than the other groups. MRI revealed focal low signal in T1 weighted images and focal high signal in T2 weighted images in group C. Pathological analysis showed more severe lesions in the gray matter than that in the white matter in group C. The model well simulated the pathogenesis and resembled the clinical characteristics of ACCSCIS. This model seems to have the potential to contribute to the development of effective therapies for ACCSCIS.

The Clinical Significance of Dark Cartilage Lesions Identified on MRI.

The purpose of this study was to determine the clinical significance of foci of low signal intensity in morphologically normal cartilage. This retrospective study included 887 patients who underwent 898 knee MRI examinations performed within 6 months of arthroscopic knee surgery. A musculoskeletal radiologist reviewed all MRI examinations for the presence of foci of low signal in cartilage where there was no visible morphologic abnormality, referred to as "dark cartilage lesions." The surgical reports of all patients were reviewed for the presence of cartilage degeneration at arthroscopy. Logistic regression was used to model the probability of dark cartilage lesions corresponding to cartilage degeneration at arthroscopy as a function of patient age. In the 5388 articular surfaces assessed on MRI, 142 dark cartilage lesions were identified. The proportion of dark cartilage lesions corresponding to cartilage degeneration at arthroscopy was 52.0% (13 of 25) in the patella, 57.1% (28 of 49) in the trochlea, 90.9% (10 of 11) in the medial femoral condyle, 50.0% (two of four) in the lateral femoral condyle, 80.0% (four of five) in the medial tibial plateau, and 70.8% (34 of 48) in the lateral tibial plateau. There was a direct correlation (R(2) = 0.89) between patient age and the likelihood that a dark cartilage lesion would correspond to cartilage degeneration at arthroscopy. Dark cartilage lesions may be found on every articular surface of the knee joint and may be a sign of otherwise occult cartilage degeneration.

Mycetoma Involving the Heart

A 59-year-old female farm worker developed a dark-centered cutaneous lesion in her right leg, associated with progressive swelling for the past 35 years. During the past 4 years, she also had dry cough and dyspnea, which became more intense for the past 6 months. She complained of asthenia and weight loss of 10 kg in the previous year. The patient had diabetes mellitus and hypertension. On physical examination, she had crackling rale at the base of the lungs, edema of the distal right lower limb, with several sinuses and ulcerated lesions of ≈1 cm with purulent discharge (Figure 1). Figure 1. Right lower foot with several ulcerated lesions with purulent discharge. Radiographic studies showed lytic foci of destruction in the medullary cavity with bone expansion, reactive sclerosis, and thickening of the cortex in right tibia and in bones of the right foot. Metatarsal bones also had cortical scalloping (Figure 2A and 2B). T1-weighted magnetic resonance image of the right foot with fat suppression after intravenous gadolinium demonstrate numerous round lesions containing small low-signal foci, also known as dot-in-circle sign, representing granulation tissue surrounded …

Enchondroma protuberans of the rib

A 20-year-old man presented with a hard and painless swelling at the left chest wall. Plain radiographs showed an expansile lesion of the third rib. Most of the lesion was intramedullary located, well-defined and osteolytic, whereas the inner portion (black arrow) was partially calcified and protruding within the chest (Fig. A). The costochondral junction was not involved. Subsequent CT confirmed the eccentric location of the lesion. The inner part contained chondroid-like calcifications and showed intimate relationship with the left lung (white arrow). There was osseous expansion resulting in focal absence of the outer cortex. Sparing of a thin layer of fat adjacent to the outer cortex was indicative of absence of soft tissue extension (Fig. B). On MRI, the outer medullary part of the lesion was of high signal on T2-weighted images, in keeping with cartilaginous matrix. The exophytic inner part (white arrow) was of intermediate signal, with internal foci of low signal due to chondroid calcifications (Fig. C).

Frantz's tumor of the pancreas

BACKGROUND: The solid-cystic tumor of the pancreas is rare, and had several names, including "papillary cystic tumor," "solid cystic tumor," "solid and papillary epithelial neoplasm." About 90% of cases are found in young women, measuring between seven and 20 cm in diameter, with 40% of them in the head, tail 32% and 28% in the body. CASE REPORT: Woman of 29 years was admitted for investigation of strong and persistent pain in right hypochondrium. It was performed ultrasonography and abdominal computed tomography, showing lobulated mass with the consistency of soft parts in the tail of the pancreas, peripheral capsular enhancement and hypovascular center measuring 5.5x5,5x5,0 cm. MRI better defined, with intermediate signal on T1 and T2, small scattered foci of low signal on T2 and peripheral enhancement by gadolinium, suggesting tumor Frantz. She underwent parcial pancreatectomy and total splenectomy. Macroscopic and microscopic findings suggested, and immunohistochemistry confirmed the diagnosis. CONCLUSION: Should be considered this tumor in the differential diagnosis of abdominal masses in young women.

A Case of Sclerosed Hemangioma Mimicking Intrahepatic Cholangiocarcinoma

Hemangioma is one of the most frequently encountered benign hepatic neoplasm which can develop secondary degeneration. Sclerosed hemangioma is a rare disease histologically characterized by large amount of collagen and elastic fibril between sclerosed small vessels. Its differential diagnosis is very difficult. It should be included in the differential diagnosis of other hepatic lesions such as hepatocellular carcinoma, intrahepatic cholangiocarcinoma, and metastatic hepatic tumor. A 77-year old male was admitted with upper abdominal discomfort. Abdominal ultrasonography revealed GB stone, dilated common bile duct with bile duct stone, and a 4.6 cm sized hyperechoic mass at segment 5 and 6 of the liver. Abdominal dynamic computed tomography demonstrated dilated intrahepatic bile ducts and a 5 x 5 cm sized mass which showed minimally delayed enhancement. Abdominal magnetic resonance imaging revealed the mass with low signal intensity in T1 weighted image, high signal intensity and focal low signal in T2 weighted image which showed minimal enhancement. We removed common bile duct stone with endoscopic retrograde cholangiopancreatography then decided to undergo right lower segmentectomy of liver due to possibility of cholangiocarcinoma. Histopathological examination of hepatic mass showed large amount of fibrous tissue with occasional residual vascular channels. We describe one case of sclerosed hemangioma mimicking cholangiocarcinoma.

Focal lesions on magnetic resonance imaging in aplastic anaemia: Multiple metastases or haemopoietic marrow

We describe the imaging findings in the spine of a 26-year-old man with aplastic anaemia who is undergoing immunosuppressive therapy. Magnetic resonance imaging of the thoracolumbar spine revealed multiple focal low signal intensity lesions involving most of the thoracic and lumbar vertebral bodies. A CT-guided biopsy of one of these lesions was performed at the level of L2, demonstrating normal haemopoietic tissue, with no evidence of lymphoma or metastases. Magnetic resonance imaging of bone marrow has been widely described previously, but few reports have examined the pattern of marrow regeneration following immunosuppressive therapy. The presence of low signal intensity lesions scattered through high signal intensity fatty marrow usually raises suspicion of pathology such as lymphoma, metastases or myeloma. In this case, the low signal intensity lesions represent regenerating, expanding haemopoietic marrow.

MR imaging of thymic epithelial tumors: correlation with World Health Organization classification

The aim of this study was to determine magnetic resonance imaging (MRI) features of various subtypes of thymic epithelial tumors based on the World Health Organization classification. The study included 64 patients with histologically proven thymic epithelial tumors. Two observers evaluated the MRI findings in terms of tumor size, contour, lobulation, shape, homogeneity, the presence of intratumor high- and low-signal foci, enhancement degree and pattern, the presence of capsule and septum, and associated mediastinal lymphadenopathy and pleural effusion. Type A tumors were more likely to have a smooth contour, round shape, distinct capsule, and smaller size compared to any other type of thymic epithelial tumor. Thymic carcinomas demonstrated a higher prevalence of low-signal foci within the mass on T2-weighted images and mediastinal lymphadenopathy than any other types. The frequency of heterogeneous intensity on T2-weighted images increased from type A tumors to thymic carcinomas. The presence of a smooth contour, round shape, and capsule is highly suggestive of a type A tumor. Foci of low signal intensity in the mass on T2-weighted images and mediastinal lymphadenopathy are highly suggestive of thymic carcinomas.

MR Imaging Findings of Acute Gouty Arthritis

Purpose: The purpose of this study was to describe the clinical and MR imaging features of acute gouty arthritis and to define the characteristic findings that would be helpful for differentiating acute gouty arthritis from septic arthritis. Materials and Methods: The authors retrospectively studied seven patients who suffered from acute gouty arthritis. The MR imaging findings were analyzed by two musculoskeletal radiologists who focused on joint effusion, subchondral bone erosion, bone marrow edema, synovial thickening (regular and even, or irregular and nodular), and the soft tissue changes (edema or abscess). The clinical records of the patients were reviewed with regard to age and gender, the clinical presentation and the laboratory findings (serum uric acid, WBC, erythrocyte sedimentation rate, C-reactive protein and synovial fluid culture). Results: The patients consisted of six men and one woman whose mean age was 41 years (age range: 24-65 years). The joints involved were the knee (n=6), and ankle (n=1). Two patients had medical histories of gouty attacks that involved the first metatarsophalangeal joint. In six cases, the serum uric acid level during acute attacks was elevated. In all the patients, the affected joint became swollen, hot, erythematous and extremely tender, and this was accompanied by a high ESR and a high C-reactive protein level at the time of presentation. The results of Gram stain and culture of the synovial fluid were negative. In all patients, the MR images showed large amounts of joint effusion, thick irregular and nodular synovial thickening and soft tissue edema without subchondral bone erosions and soft tissue abscess. In one case, subchondral bone marrow edema of the medial femoral condyle was present. In five cases, there were multiple low signal foci in the joint on the spin-echo T2-weighted MR image. Conclusion: Even though the MR imaging findings of acute gouty arthritis are nonspecific, it should be considered as a possible diagnosis when a large amount of joint effusion, irregular and nodular synovial thickening and soft tissue edema without subchondral bone erosion, bone marrow edema or soft tissue abscess are seen in the knee or ankle joint, and especially if this is accompanied by the clinical and laboratory features of infection

Is haemosiderin visible indefinitely on gradient-echo MRI following traumatic intracerebral haemorrhage?

Gradient-echo (GE) MRI has been demonstrated to be the most sensitive current technique for detection of intracerebral haemosiderin, especially in the chronic stage of haemorrhage. Our purpose was to see whether GE MRI shows old haemorrhage indefinitely. We reviewed serial GE images of 105 adults with imaging features consistent with post-traumatic intracerebral haemorrhage, who had serial MRI at 1, 4-6, 12, and 24 months after trauma. Of 1235 scattered low-signal foci consistent with isolated intracerebral haemosiderin deposits on images at 4-6 months, 248 (20.1%) were not seen at 24-month assessment. Reviewing individual patients, we saw that in 71.8% of those with scattered haemosiderin deposits and 46.4% of those with haemosiderin surrounded by gliosis, the low-signal foci appeared less conspicuous with time. Even given certain limitations to the interpretation of these findings, it would appear that, even with the use of GE MRI, time affects the visibility of haemorrhagic intracerebral lesions. We therefore conclude that a time of 4-6 months to 1 year or slightly more should be recommended for most precise detection of haemosiderin deposits on MRI of head-injured patients, should this be thought desirable. Normal GE images may not exclude old haemorrhage.

Tophaceous Gout of the Spine: MR Imaging Features

AIM: To define the magnetic resonance (MR) imaging features of tophaceous gout of the spine. MATERIALS AND METHODS: We present the MR imaging examinations of 4 patients with spinal tophaceous gout. Spin-echo T1-weighted and fast spin-echo T2-weighted images were obtained for all patients, and 2 patients had gadolinium-enhanced MR imaging studies. Corresponding computed tomography (CT) was performed in one patient. All images were evaluated for the characteristics of the gouty tophi. RESULTS: The gouty tophi were located at the lower thoracic (n=1) and lumbar (n=3) levels. All tophi yielded homogeneous intermediate to low signal on T1-weighted images and variable signal intensity on T2-weighted images, comprising small foci of very low signal intensity on all sequences. Gadolinium-enhanced MR imaging studies revealed homogeneous enhancement or heterogeneous peripheral enhancement. Diffuse stippled calcifications were found in the tophi on CT images. Periarticular tophi with juxtaarticular bony erosions around facet joints occurred in 3 patients. CONCLUSION: Spinal tophaceous gout should be considered in the differential diagnosis when periarticular deposits contain very low signal foci on all MR imaging sequences. Hsu, C.-Y. et al. (2002)Clinical Radiology57, 919–925.

Idiopathic synovial osteochondromatosis of the hip: radiographic and MR appearances in 15 patients.

ObjectiveTo evaluate the radiographic and MR appearance of idiopathic synovial osteochondromatosis of the hip.Materials and MethodsRadiographs and MR images of 15 patients with idiopathic synovial osteochondromatosis of the hip were assessed. The former were analysed in terms of the presence of 1) juxta-articular calcified and/ or ossified bodies, 2) osteophytes, 3) bone erosion, 4) juxta-articular osteopenia, and 5) joint space narrowing, while for the latter, analysis focused on 1) the configuration of intra-articular bodies, 2) bone erosion, 3) synovial thickening, 4) conglomeration of intra-articular bodies, and 5) extra-articular extension.ResultsAt hip radiography, juxta-articular calcified and/ or ossified bodies were seen in 12 of the 15 patients (80%), bone erosion in eight (53%), osteophytes in seven (47%), juxta-articular osteopenia in five (33%) and joint space narrowing in five (33%). In eight patients (53%), MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, and areas of iso-intensity at T1WI and hyperintensity at T2WI. In three (20%), intra-articular bodies of focal low signal intensity and areas of hyperintensity at all pulse sequences were observed, with areas of iso-intensity at T1WI and hyperintensity at T2WI, while in four (27%), intra-articular bodies of only focal low signal intensity at all pulse sequences were apparent. Synovial thickening was present in 13 patients (87%), bone erosion in 11 (73%), conglomeration of the intra-articular bodies in 11 (73%), and an extra-articular herniation sac in six (40%).ConclusionThe most common radiographic finding of synovial osteochondromatosis of the hip was the presence of juxta-articular calcified and/ or ossified bodies. MR imaging depicted intra-articular bodies of focal low signal intensity at all pulse sequences, with areas of iso-intensity at T1WI and hyperintensity at T2WI. In addition, the presence of an extra-articular herniation sac was not uncommon.

Magnetic resonance imaging features of allografts.

To investigate the magnetic resonance imaging (MRI) features of allografts at various time intervals after surgery in patients with osteoarticular allografts. Sixteen patients who were treated with osteoarticular allografts and who were followed over time with MRI studies as part of their long-term follow-up were retrospectively selected for this study. T1-weighted images were obtained both before and after gadolinium administration along with T2-weighted images. All images were reviewed by an experienced musculoskeletal radiologist, with two other experienced radiologists used for consultation. Imaging studies were organized into three groups for ease of discussion: early postoperative period (2 days to 2 months), intermediate postoperative period (3 months to 2 years), and late postoperative period (greater than 2 years). In the early postoperative period, no gadolinium enhancement of the allograft was visible in any of the MR images. A linear, thin layer of periosteal and endosteal tissue enhancement along the margin of the allograft was visible in images obtained at 3-4 months. This enhancement appeared gradually to increase in images from later periods, and appears to have stabilized in the images obtained approximately 2-3 years after allograft placement. The endosteal enhancement diminished after several years, with examinations conducted between 6 and 8 years following surgery showing minimal endosteal enhancement. However, focal enhancement was noted adjacent to areas of pressure erosion or degenerative cysts. All the cases showed inhomogeneity in the marrow signal (scattered low signal foci on T1 with corresponding bright signal on T2), and a diffuse, inhomogeneous marrow enhancement later on. We have characterized the basic MRI features of osteoarticular allografts in 16 patients who underwent imaging studies at various time points as part of routine follow-up. We believe that the endosteal and periosteal enhancement observed on MRI during the first few months to 2 years following surgery represents vascular ingrowth and early skeletal repair. The zone of periosteal enhancement could also include the new bone laid on the surface of the allograft through which the soft tissues bind to the cortex. The exact reason for the inhomogeneity in the marrow signal, and the diffuse, inhomogeneous marrow enhancement is not clear. This may represent saponified and/or necrotic marrow fat interspersed with the fibrovascular tissue. The features noted here should provide radiologists with useful information regarding imaging characteristics they can expect to see in other allograft replacement patients.

Peripheral focal low signal intensity areas in the degenerated annulus fibrosus on T2-weighted fast spin echo MR images: correlation with macroscopic and microscopic findings in elderly cadavers.

To correlate the peripheral focal low signal intensity areas in the degenerated annulus fibrosus on T2-weighted fast spin echo MR images with the macroscopic and microscopic findings in cadavers derived from elderly subjects. Twenty-eight intervertebral disks (16 lumbar and 12 cervical) derived from four nonembalmed cadavers were examined with T1-weighted spin echo and proton density-weighted and T2-weighted fast spin echo MR imaging. The signal intensities of the annulus fibrosus were evaluated on sagittal MR images and correlated with the findings on corresponding sagittal anatomic sections. The MR imaging-histologic correlation was then studied. Peripheral focal low signal intensity areas and adjacent regions of high signal intensity were found in five lumbar intervertebral disks. Peripheral focal low signal intensity regions consisted of disorganized compact annular fibers, tiny fissures, and dense fibrosis. The high signal intensity regions, adjacent to the areas of low signal intensity, consisted of mucoid degeneration, tiny fissures, and chondroid metaplasia. Awareness of the histologic findings in regions that reveal peripheral focal low signal intensity with adjacent regions of high signal intensity in the degenerated annulus fibrosus on T2-weighted images may facilitate effective interpretation of clinical MR images of the spine.

Hippocampal atrophy in recurrent major depression.

Hippocampal volumes of subjects with a history of major depressive episodes but currently in remission and with no known medical comorbidity were compared to matched normal controls by using volumetric magnetic resonance images. Subjects with a history of major depression had significantly smaller left and right hippocampal volumes with no differences in total cerebral volumes. The degree of hippocampal volume reduction correlated with total duration of major depression. In addition, large (diameter > or = 4.5 mm)-hippocampal low signal foci (LSF) were found within the hippocampus, and their number also correlated with the total number of days depressed. These results suggest that depression is associated with hippocampal atrophy, perhaps due to a progressive process mediated by glucocorticoid neurotoxicity.