Short Tau Inversion Recovery Images Research Articles

Association of preoperative magnetic resonance imaging findings with surgical features in Dachshunds with thoracolumbar intervertebral disk extrusion

To evaluate the accuracy of specific magnetic resonance imaging (MRI) sequences in determining the site, lateralization, and extent of extruded intervertebral disk material (EIDM), compared with surgical findings, in Dachshunds with thoracolumbar intervertebral disk extrusion (TLIDE). Prospective clinical study. 16 Dachshunds with clinical signs of intervertebral disk disease. Preoperative T1-weighted, T2-weighted, and short tau inversion recovery (STIR) MRI measurements and description of the location of EIDM were compared with intraoperative measurements and determination of the EIDM position. The T12-13 intervertebral disk space was the most frequent site of EIDM (6/16 dogs). The EIDM lateralized with equal frequency to the left and right sides; no central extrusions were seen. There was moderate to substantial agreement (kappa, 0.59) between MRI and surgical findings for evaluation of the craniocaudal distribution of the EIDM. For measurement of the length of EIDM, the T1-weighted, T2-weighted, and STIR sequences had a mean error of -1.15, -0.38, and -1.93 mm, respectively; concordance correlation coefficients were 0.666, 0.904, and 0.458, respectively. Mean absolute errors were 2.54, 1.35, and 2.90 mm, respectively; these values did not differ significantly. In the thoracolumbar vertebral column of Dachshunds with clinical signs of intervertebral disk disease, MRI is a valuable technique for determining location and craniocaudal length of EIDM. Compared with T1-weighted and STIR images, T2-weighted images appeared to be more accurate and precise and are potentially more reliable for determination of the length of EIDM in those dogs.

Pelvic phased-array MR imaging of anal carcinoma before and after chemoradiation

The aim of this study was to evaluate the MR findings of anal carcinoma using an external pelvic phased-array coil before and after chemoradiation treatment. 15 patients with carcinoma of the anal canal underwent T(2) weighted and short-tau inversion recovery (STIR) imaging before and after chemoradiation. Images were reviewed in consensus by two radiologists. At pre-treatment imaging, the tumour size and stage, signal intensity and infiltration of adjacent structures were recorded. MR imaging was repeated immediately after chemoradiation, every 6 months for the first year and then yearly. Tumour response was assessed by recording change in tumour size and signal intensity. Prior to treatment, the mean tumour size was 3.9 cm (range, 1.8-6.4 cm). Tumours appeared mildly hyperintense at T(2) weighted and STIR imaging. There was good agreement in T staging between clinical examination and MR imaging (kappa = 0.68). In 12 responders with long disease remission, a greater percentage reduction in the size of MR signal abnormality in the tumour area was observed at 6 months (mean 54.7%; 46-62%) than immediately after treatment (mean 38.6%; 30-46%) (p = 0.002, t-test). 7/12 showed stabilization of T(2) signal reduction in the tumour area after 1 year, and 5/12 showed complete resolution of signal alterations at 2 years. Pelvic phased-array MR imaging is useful for local staging of anal carcinoma and assessing treatment response. After treatment, a decrease in tumour size accompanied by reduction and stability of the MR T(2) signal characteristics at 1 year after chemoradiation treatment was associated with favourable outcome.

MRI of the thorax during whole‐body MRI: Evaluation of different MR sequences and comparison to thoracic multidetector computed tomography (MDCT)

To evaluate the accuracy of four MR sequences used as part of a whole-body MRI protocol to detect pulmonary lesions in cancer patients. A total of 31 oncology patients were imaged in a 1.5T MR scanner (Magnetom Avanto; Siemens Medical Solutions, Germany) for whole-body staging. MR chest imaging included: axial and coronal T2-weighted (T2w)-short-tau inversion-recovery (STIR), axial T2w turbo spin-echo (TSE), and contrast-enhanced (CE) three-dimensional (3D) volumetric interpolated breathhold examination (VIBE). Multidetector computed tomography (MDCT) of the thorax served as the reference standard. The MDCT and MR images were evaluated independently by two radiologists. Comparative analysis was performed per lesion, per lobe, and per patient. Sensitivity, specificity, and predictive values were determined. Compared to MDCT that detected 268 pulmonary lesions ranging from 2 to 75 mm in diameter, the MR sensitivities were 91.1%, 92.5%, 90.8%, and 87.3% for the coronal STIR, the axial STIR, the axial T2w-TSE, and the axial CE 3D-VIBE, respectively. Undetected pulmonary lesions were either calcified or smaller than 10 mm in the axial diameter. With coronal STIR, six false-positive findings were detected; with axial STIR, 14 were detected; with axial T2w-TSE, 10 were detected; and with 3D-VIBE, seven were detected. Pulmonary MRI is feasible as part of a whole-body MRI protocol. In our study, STIR images achieved high accuracy compared to chest MDCT for pulmonary lesions of 3 mm in size or larger.

Spinal Nerve Root Hypertrophy on MRI: Clinical Significance in the Diagnosis of Chronic Inflammatory Demyelinating Polyradiculoneuropathy

To investigate the clinical usefulness of measuring diameters of spinal nerve roots on magnetic resonance imaging (MRI) in patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) with regard to the diagnosis and estimation of neurofunctional impairment. Fourteen patients with CIDP (mean age, 38.9+/-19.2 years) and 10 controls were enrolled in this study. Diameters of cervical and lumbosacral spinal nerve roots were determined on the short tau inversion recovery image of MRI. Correlations between these diameters and clinical indices, including the conduction velocity of median and tibial nerves, were examined. Mean diameters of cervical and lumbosacral spinal nerve roots in CIDP patients were 6.0 to 6.8 mm and 7.3 to 10.4 mm, respectively. CIDP patients showed higher values of the diameter in C5 (p<0.05), C6 (p<0.05), C7 (p<0.005) and C8 (p<0.01) than controls. C7 and C8 showed significantly negative correlations between diameters of spinal nerve roots and the F-wave conduction velocity (FWCV) (p<0.05). In the lumbosacral region, L3, L4 and S1 showed significantly negative correlations between diameters of spinal nerve roots and FWCV (p<0.005, p<0.0005 and p<0.005, respectively). The latency-time difference between F- and M-waves increased with diameters of spinal nerve roots, and there were significantly positive correlations between them in L3 (p<0.05) and L4 (p<0.005). Hypertrophy of spinal nerve roots shown on MRI may be useful as a clue to the diagnosis of CIDP and also as a clinical marker suggesting impairment of peripheral nerve conduction, particularly FWCV.

MAGNETIC RESONANCE IMAGING FEATURES OF ORBITAL INFLAMMATION WITH INTRACRANIAL EXTENSION IN FOUR DOGS

This retrospective study describes the clinical and magnetic resonance (MR) imaging features of chronic orbital inflammation with intracranial extension in four dogs (two Dachshunds, one Labrador, one Swiss Mountain). Intracranial extension was observed through the optic canal (n=1), the orbital fissure (n=4), and the alar canal (n=1). On T1-weighted images structures within the affected skull foramina could not be clearly differentiated, but were all collectively isointense to hypointense compared with the contralateral, unaffected side, or compared with gray matter. On T2-, short tau inversion recovery (STIR)-, or fluid-attenuated inversion recovery (FLAIR)-weighted images structures within the affected skull foramina appeared hyperintense compared with gray matter, and extended with increased signal into the rostral cranial fossa (n=1) and middle cranial fossa (n=4). Contrast enhancement at the level of the affected skul foramina as well as at the skull base in continuity with the orbital fissure was observed in all patients. Brain edema or definite meningeal enhancement could not be observed, but a close anatomic relationship of the abnormal tissue to the cavernous sinus was seen in two patients. Diagnosis was confirmed in three dogs (one cytology, two biopsy, one necropsy) and was presumptive in one based on clinical improvement after treatment. This study is limited by its small sample size, but provides evidence for a potential risk of intracranial extension of chronic orbital inflammation. This condition can be identified best by abnormal signal increase at the orbital fissure on transverse T2-weighted images, on dorsal STIR images, or on postcontrast transverse or dorsal images.

MAGNETIC RESONANCE IMAGING OF SUBARTICULAR BONE MARROW LESIONS IN DOGS WITH STIFLE LAMENESS

A bone bruise is a magnetic resonance (MR) imaging sign thought to signify acute traumatic microfracture of trabecular bone with hemorrhage and edema in the marrow that may occur without grossly visible disruption of the adjacent cortices or overlying cartilage. In approximately 75% of people with acute anterior-cruciate ligament tears, bone bruises are detected in characteristic locations within the femur and tibia and are best seen as high-signal lesions using fat-suppression sequences. We questioned whether this is a component of naturally acquired stifle lameness in dogs and obtained short-tau inversion recovery (STIR) images of six dogs with stifle lameness. High-signal STIR lesions were detected in five of six (83%) dogs and eight of 12 (67%) limbs. We observed these lesions deep to the intercondylar fossa of the femur and intercondylar eminence of the tibia, which are atypical locations in people. High-signal STIR lesions were detected in dogs with only synovitis, partial tear of the cranial cruciate ligament (CCL) and complete tear of the CCL. One of these lesions was seen in the lateral tibial condyle, a typical location in humans with acute anterior cruciate ligament tear. As the MR imaging appearance of stress fractures and bone bruises are similar, and the high-signal STIR lesions are at attachment sites of the CCL, this finding may be due to stress disease or other unknown causes, rather than bone bruising. High-signal STIR lesions may be a common sign in naturally acquired canine stifle disease, but the pathogenesis, prognostic and diagnostic values need further investigation.

Short-term outcome of painful bone marrow oedema of the knee following oral treatment with iloprost or tramadol: results of an exploratory phase II study of 41 patients

To compare the therapeutic effects of oral iloprost and tramadol on the outcome of bone marrow oedema (BME) of the knee by MR imaging and clinical assessment. Forty-one patients with painful ischemic or mechanical BME of the knee were enrolled in a double-blind, randomized controlled study. Patients were randomized either to iloprost (n = 21, group 1) or tramadol (n = 20, group 2). The treatment duration was 4 weeks. The Larson knee score was used to assess function before treatment and then 3 days, 1, 2, 3, 4 weeks and 3 months after the start of treatment. Short tau inversion recovery and T1-weighted MR images of the affected knees were obtained before and 3 months after the start of treatment. Bone marrow oedema was assessed visually and by computer-assisted quantification for baseline and follow-up MR examinations. Thirty-three patients completed the study as scheduled. The mean Larson score improved from 58.6 points to 81.8 points in group 1, and from 59.6 points to 86.8 points in group 2, after 3 months (no significant difference between the treatment groups). On MR images, complete BME regression in at least one bone was observed in nine patients (52.9%) in group 1, as opposed to three patients (18.7%) in group 2, after 3 months (P = 0.034). Correspondingly, the median BME volume decreased by 58.0% in group 1, and by 47.5% in group 2. The analgesic effect of iloprost and tramadol was similar. BME regression on MR images was more pronounced under iloprost treatment.

Rhabdomyolysis

Our purpose was to describe the magnetic resonance (MR) imaging and computed tomography (CT) findings in patients with rhabdomyolysis. The medical records and imaging studies of 10 patients (5 males, 5 females; age range, 14-60 years; mean age, 28.3 years) with rhabdomyolysis were retrospectively reviewed. Magnetic resonance imaging was available in 9 patients and CT in 2 patients. Two distinct imaging types of rhabdomyolysis were observed. For type 1 rhabdomyolysis (n = 2), the affected muscles revealed homogeneously isointense to hyperintense on T1-weighted, homogeneously hyperintense on T2-weighted and short-tau inversion recovery (STIR) images, and homogeneously enhanced on contrast-enhanced MR images. For type 2 rhabdomyolysis (n = 8), the affected muscles revealed homogeneously or heterogeneously isointense to hyperintense on T1-weighted images, heterogeneously hyperintense on T2-weighted and STIR images, heterogeneously hypodense on CT images, and rim enhanced on contrast-enhanced MR and CT images with the presence of a specific presentation, named as the "stipple sign." Rhabdomyolysis is a clinical and biochemical syndrome comprising 2 distinct imaging types. Homogeneous signal changes and enhancement in the affected muscles advocate type 1 rhabdomyolysis. The stipple sign is helpful in demonstrating the areas of myonecrosis in type 2 rhabdomyolysis and, together with clinical and laboratory presentations, in reaching the correct diagnosis.

MRI appearance of multiple eccrine spiradenoma

Multiple eccrine spiradenoma is one of the rarest tumours of the sweat gland. We report a case of multiple eccrine spiradenoma that was distributed in several parts of the body. On MRI the lesions presented with multiple dispersive foci with clear circumferences in the cutis and the subcutaneous tissue. The lesions showed low signal intensity on T1 weighted images, and high signal intensity on short tau inversion recovery images. Although the signal intensities of the lesions were not characteristic in this patient, multiple eccrine spiradenoma should be included in the differential diagnosis of the lesions in the cutis and the subcutaneous tissue.

Magnetic resonance imaging and radiographic findings of seal finger

To describe the magnetic resonance imaging (MRI) and radiographic findings of five patients with seal finger. The MR images and radiographs of five patients with seal finger were retrospectively evaluated. MRI was performed on four patients in the subacute phase, and follow-up imaging was done on one of them at 5 months. One patient had MRI only at a later stage 5 years after onset. Radiographs were taken three times in the subacute phase and once at a later stage. One patient had had seal finger in another finger previously. Short-tau inversion-recovery (STIR) sequence showed extensive subcutaneous soft tissue edema in all four patients in the subacute phase and tenosynovitis of the flexion tendons in two cases. Three patients had edema in 2-3 phalanges, and effusion in the distal interphalangeal (DIP) joint was seen in one case. At the later stage, no signal pathology in soft tissues or bones was seen in STIR images. In the subacute phase, radiographs showed digital soft-tissue swelling in three patients, and one patient had a narrowed DIP joint, periarticular osteoporosis, and a periosteal reaction. At the later stage, flexion contracture of the finger was seen. In addition to soft-tissue infection, seal finger causes bone marrow edema, tenosynovitis, and effusion in the interphalangeal joints visible as increased signal intensity in STIR images. Radiographs reveal periarticular osteoporosis with loss of cartilage in the subacute phase and flexion contracture at the later stage. MRI (STIR) allows more precise delineation of the inflammatory process compared to radiography.

Non-arteritic anterior ischaemic optic neuropathy: evaluation of the brain and optic pathway by conventional MRI and magnetisation transfer imaging

The purpose of the study was to examine the brain and the visual pathway of patients with non-arteritic anterior ischaemic optic neuropathy (NAION) by using conventional MRI (cMRI) and volumetric magnetisation transfer imaging (MTI). Thirty NAION patients, aged 67.5 +/- 8.14 years, and 28 age- and gender-matched controls were studied. MTI was used to measure the magnetisation transfer ratio (MTR) of the chiasm and for MTR histograms of the brain. The presence of areas of white matter hyperintensity (WMH) was evaluated on fluid-attenuated inversion recovery (FLAIR) images. Area of the optic nerves (ONs) and volume of the chiasm were assessed, as were coronal short-tau inversion recovery (STIR) and MTI images, respectively. More areas of WMH were observed in patients (total 419; mean 14.4; SD 19) than in controls (total 127; mean 4.7; SD 5.7), P < 0.001. Area (in square millimetres) of the affected ONs, volume(in cubic millimetres) and MTR (in percent) of the chiasm (10.7 +/- 4.6), (75.8 +/- 20.2), (56.4 +/- 6.5), respectively, were lower in patients than in controls (13.6 +/- 4.3), (158.2 +/- 75.3) (62.1 +/- 6.2), respectively, P < 0.05. Mean MTR of brain histograms was lower in patients (53.0 +/- 8.0) than in controls (58.0 +/- 5.6), P < 0.05. NAION is characterised by decreased ON and chiasmatic size. The low MTR of the chiasm and brain associated with increased areas of WMH may be suggestive of demyelination and axonal damage due to generalised cerebral vascular disease.

Acetaminophen, like conventional NSAIDs, may reduce synovitis in osteoarthritic knees

To determine the extent to which treatment of patients with symptomatic knee osteoarthritis (OA) with non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen (ACET) reduces total effusion volume and synovial tissue volume, as quantified by magnetic resonance imaging (MRI). Sequential pilot studies used subjects whose knee OA was treated with NSAIDs (n=10) or with ACET <or=4 g/day (n=20), respectively. After a five half-lives washout of their pain medication, the OA knee with the higher pain score >or=15 of 25 on the Western Ontario and McMaster Universities' pain scale underwent l.5T MRI. Effusion was quantified in axial short tau inversion recovery images; to measure synovial tissue volume, fat-suppressed T1-weighted axial images were obtained 3 min after i.v. injection of gadolinium contrast. After the initial MRI examination, patients resumed their customary pain medications until the severity of knee pain returned to baseline, when pain was again measured and the MRI was repeated. Pain severity after washout was similar in subjects taking ACET and NSAIDs. Reinstitution of ACET resulted in a 50% decrease in the mean of pain scores (P=1.7 x 10(-12)) that was comparable with that seen after the reinstitution of NSAID (49%, P=6.0 x 10(-7)). The mean total effusion volume measured during the flare of knee pain induced by the withdrawal of the two drugs was comparable (ACET 16.9 ml, NSAID 16.2 ml; P=0.884). Significant decreases in mean total effusion volume were observed after reinstitution of both ACET (-4.5 ml, P=0.009) and NSAID (-3.3 ml, P=0.013); the difference between drugs was not significant. Analyses of synovial volume yielded similar results. While uncontrolled and derived from small samples, these data suggest that ACET may have a significant anti-inflammatory effect in patients with knee OA, comparable with that achieved with NSAIDs, possibly through an effect on neurogenic inflammation. Joint pain is the clinical feature of OA that most often leads the affected individual to seek medical attention. Because many patients with OA improve symptomatically with the use of NSAIDs, it has been widely assumed that the pain of OA is due to synovial inflammation. However, the origins of OA pain are numerous and may vary from patient to patient and, within the same subject, from visit to visit. Although the articular cartilage is usually the site of the most obvious pathological changes in this disease, it is aneural and, therefore, is not the source of joint pain. However, in addition to the synovium, the subchondral bone, joint capsule, osteophytes, menisci, ligaments, periarticular tendons, entheses and bursae all contain nociceptive nerve endings, stimulation of which by chemical or physical mediators may be a basis for OA pain.

High-resolution MR imaging of the proximal zone of the lunotriquetral ligament with a microscopy coil

To evaluate high-resolution MRI of the proximal zone of the lunotriquetral ligament (LTL) using a microscopy surface coil with a 1.5 T scanner. The proximal zone of the LTL was reviewed in 90 subjects (23 asymptomatic normal volunteers and 67 patients with suspicion of triangular fibrocartilage complex injury) with high-resolution MRI using a 47-mm microscopy surface coil. High-resolution MR images were obtained with gradient recalled echo (GRE) T2*-weighted sequence and short tau inversion recovery imaging, with a 1- to 1.5-mm slice thickness, a 50-mm field of view, an imaging matrix of 140-224x512 using zero fill interpolation, and 3-4 excitations. As a qualitative analysis, the LTL was classified in shape and signal intensity. The triangle-shaped low-signal-intensity LTL was identified in 77 of 90 subjects (85.6%) on GRE images. The triangle was classified as regular (41.1%), broad-based (20.0%), narrow-based (6.7%), or asymmetrical (17.8%). The bar-shaped ligament was seen in one patient, and unclassified ligaments were seen in 12 patients. All volunteers showed triangle-shaped LTL. The MR signal intensity of the proximal zone in the LTL was characterized as homogeneously low intensity (type 1; 33.8%), linear intermediate or high signal intensity traversing the distal surface of the LTL (type 2; 45.5%), and linear intermediate or high intensity traversing both distal and proximal surfaces of LTL (type 3; 20.8%). The proximal zone of the LTL showed a broad spectrum of normal variations in shape and signal intensity on high-resolution MR images with a microscopy coil.

Low‐field compact magnetic resonance imaging system for the hand and wrist in rheumatoid arthritis

To investigate the feasibility of an originally developed compact MRI system for evaluating rheumatoid arthritis (RA), and determine its advantages and disadvantages as an imaging modality for evaluating RA. We prospectively studied 13 healthy controls with no clinical symptoms of arthritis, and 13 patients with hand and wrist pains (including pain from RA) with a 0.2 T permanent-magnet compact MR imager. All MR images were obtained while the subjects were in a sitting position. Coronal three-dimensional spin-echo T1-weighted images and coronal two-dimensional short tau inversion recovery (STIR) images were obtained with image matrix = 256 x 128 and field of view (FOV) = 20.48 cm. Plain radiograph findings and MRI findings of patients were compared. In three of the patients with suspected early RA (N = 7), early RA was evaluated based on STIR images. All RA patients showed morphologic or signal intensity changes that allowed an evaluation of RA from MR findings. Four of five RA patients showed high signal intensity on STIR images in the wrist, proximal interphalangeal (PIP) joint, or metacarpophalangeal (MCP) joint that suggested synovitis. Multiple erosions in the hand and wrist were seen in four RA patients, with low signal intensity on T1-weighted images. RA was correctly evaluated, and early RA could be identified with the compact MRI system. However, the current system has limitations, such as the nonselective STIR sequence used and magnetic field inhomogeneity.

Coronal oblique turbo STIR imaging of the sacrum and sacroiliac joints at routine MR imaging of the lumbar spine

The objective of the study was to evaluate the clinical impact of coronal oblique imaging of the lumbrosacral junction and the sacrum at initial presentation for MR imaging of the lumbar spine in patients presenting with low back pain or sciatic pain. Two hundred and sixty consecutive patients attending for MRI of the lumbar spine underwent simultaneous coronal oblique turbo short tau inversion recovery (STIR; TR 2500, TE 40, TI 150, echo train length 7, number of scan acquisitions 2) imaging of the sacrum and the sacroiliac joints with a field of view of 30-cm and 3-mm slices (acquisition time 3 min and 20 s). Images were reviewed by two experienced radiologists to determine the cause of back pain, with and without images of the sacrum and sacroiliac joints. The added value of the additional sequence was assessed. Correlation was made with surgery, response to nerve root injection or clinical follow-up at 3 months. Subgroup analysis was performed to determine if patient stratification according to sex or symptoms would be useful. In total, in 19 of 260 patients (7.3%), abnormalities were identified at coronal STIR imaging. In 7 of 260 patients (2.7%), pathology was identified in the sacrum thought to account for back pain, altering the diagnosis made on the standard sequences. These diagnoses were sacroiliitis (n=2), sacral stress fracture (n=1), degenerative sacroiliac joints (n=1), degenerative accessory articulation between the lumbar spine and the sacrum (n=1), Tarlov cyst of nerve root (n=1) and retroverted uterus causing sciatic pain (n=1). Patient stratification according to sex or the presence or absence of sciatic symptoms was not useful in predicting the added benefit of the additional sequence. Routine coronal STIR imaging of the sacrum as part of lumbar spine MRI improves assessment of patients presenting with low back pain or sciatica in only a small number of patients.

STIR vs. T1‐weighted fat‐suppressed gadolinium‐enhanced MRI of bone marrow edema of the knee: Computer‐assisted quantitative comparison and influence of injected contrast media volume and acquisition parameters

To compare short tau inversion recovery (STIR) and T1-weighted (T1w) gadolinium (Gd)-enhanced fat-suppressed MRI of bone marrow edema (BME) of the knee, and investigate the influence of injected contrast media volume and variation of major acquisition parameters on apparent BME volume and signal contrast. STIR and T1w Gd-enhanced fat-suppressed images were obtained from 30 patients with BME of the knee. Two groups of patients were examined with different MR scanners, acquisition parameters, and contrast media volumes. For both sequences, BME volume and signal contrast were assessed by computer-assisted quantification, and were compared through their arithmetic means and correlation coefficients (r(2)). The injected contrast media volume was also correlated with BME volume and signal contrast differences between sequences. A strong correlation between the STIR and Gd-enhanced T1w images was found for BME volume (r(2) = 0.96-0.99) and BME signal contrast (r(2) = 0.86-0.94). Despite the differences in MR acquisition parameters and injected contrast media volume, both sequences depicted an almost identical BME volume in both groups. Contrast media volume showed a moderate correlation (r(2) = 0.40) with BME volume differences. STIR is the optimum method for determining the size and signal contrast of BME. The injected contrast media volume appears to have only a limited influence on apparent BME volume.

Is there a need for contrast-enhanced T1-weighted MRI of the spine after inconspicuous short τ inversion recovery imaging?

To assess the use of contrast-enhanced T1-weighted images in comparison with short tau inversion recovery (STIR) images for the detection of vertebral bone marrow abnormalities. A total of 201 vertebral magnetic resonance (MR) examinations were included in a prospective trial. Examinations were performed on a 0.5-T MR scanner. The examination protocol included STIR, T2-weighted turbo spin-echo and T1-weighted spin-echo images before and after administration of gadopentetate dimeglumine. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of STIR images were calculated. In the case of abnormal STIR images the additional information from contrast-enhanced images was evaluated using Fisher's exact test. The value of the combined evaluation of STIR and contrast-enhanced T1-weighted images was compared with that of the combined assessment of T2-weighted and contrast-enhanced T1-weighted images. The PPV and the NPV of STIR images for detection of vertebral bone marrow abnormalities were 99.3 and 95.9%. In the case of normal STIR images no relevant additional information was found with contrast-enhanced T1-weighted images, while in the case of abnormal STIR images significant supplementary information was obtained. There was no difference in the diagnostic value when comparing combined assessment of STIR and contrast-enhanced T1-weighted images with combined evaluation of T2-weighted and contrast-enhanced T1-weighted images. Normal STIR images allow contrast-enhanced T1-weighted images for detection of bone marrow abnormalities to be omitted, whereas further imaging is needed in case of abnormal STIR images.

Conspicuity of liver hemangiomas: Short tau inversion recovery, T1, and T2 imaging with gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid

To compare conspicuity of liver hemangiomas on STIR, T1-weighted, and T2-weighted magnetic resonance (MR) images before and after administration of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) (hepatocellular contrast agent), using contrast-to-noise ratios (CNRs). Thirteen hemangiomas were imaged using breath-hold gradient echo (GRE) T1, fat-saturated turbo spin echo (TSE)-T2, and short tau inversion recovery (STIR) sequences. Background noise and signal-to-noise ratios (SNRs) for liver and hemangioma, along with CNR for normal liver and hemangioma, were measured on each sequence before and after administration of Gd-EOB-DTPA. Hemangioma conspicuity was also evaluated qualitatively. After Gd-EOB-DTPA administration, the quantitative liver SNR decreased 54% on STIR, increased 45% on T1-weighted images, and increased 14.5% on TSE-T2-weighted images. The CNR for liver and hemangioma increased 50% on STIR images (P < 0.0001), increased 46% on T1-weighted imaging (P = 0.0033), and increased 22% on TSE-T2-weighted MR imaging (MRI) (P = 0.0083). After contrast, the CNR for TSE-T2 images was greater than those for both the T1 and STIR images (P < 0.0001 for both). Qualitatively, signal change was visually apparent in the liver on T1 and STIR, but not on T2 images or in the hemangiomas on any sequence. Despite the statistically significant T1 and STIR increase in CNR, liver hemangiomas were most conspicuous on TSE-T2 images after Gd-EOB-DTPA. This pilot study with hemangiomas highlights the newly recognized potential benefit of TSE-T2 imaging with hepatocellular contrast.

INJURY OF THE COLLATERAL LIGAMENTS OF THE DISTAL INTERPHALANGEAL JOINT DIAGNOSED BY MAGNETIC RESONANCE

We describe the clinical, imaging, and necropsy findings of two horses with severe injury of the collateral ligaments of the distal interphalangeal (DIP) joint diagnosed using magnetic resonance (MR) imaging. In MR images it was possible to examine the collateral ligaments of the DIP joint from the origin at the middle phalanx to the insertion on the distal phalanx. Both horses in this report had abnormal high signal intensity within the collateral ligaments of the DIP joint, and one horse had abnormal high signal intensity within the bone of the distal phalanx on short tau inversion recovery (STIR) and T2-weighted imaging sequences. High signal intensity on STIR and T2-weighted images represents abnormal fluid accumulation indicative of inflammation, within ligament, tendon, or bone on these imaging sequences. Abnormalities were confirmed on necropsy in both horses. Injury of the collateral ligaments of the DIP joint should be considered as a source of pain in horses with lameness localized to the foot.

MR imaging of abdominopelvic involvement in neurofibromatosis type 1: a review of 43 patients

Plexiform neurofibromas are a frequent complication of neurofibromatosis type 1. This article discusses MR imaging findings and distribution of plexiform neurofibromas in the abdomen and pelvis. To define the most prevalent patterns of involvement and MR imaging findings in abdominopelvic neurofibromatosis type 1. We reviewed the MR appearance of abdominopelvic lesions in 23 male and 20 female patients (median age: 16 years) with type 1 neurofibromatosis. The patients were part of a multi-institutional study of 300 patients. Imaging included coronal or sagittal, and axial short tau inversion recovery images. The most common abdominopelvic involvement was in the abdominopelvic wall (n=28, 65%) and lumbosacral plexus (n=27, 63%). Retroperitoneal involvement was frequent (n=15, 35%). Lesions were less often intraperitoneal (21%) (P=0.001). Pelvic disease (n=27, 63%), neural canal involvement (n=18, 42%), and hydronephrosis (n=4, 9%) were also noted. Target-like appearance of plexiform lesions was noted in more than half the patients. Abdominopelvic involvement in neurofibromatosis type 1 is primarily extraperitoneal. Although lesions are most prevalent in the abdominopelvic wall and lumbosacral plexus, retroperitoneal and pelvic involvement is common and usually affects important organs. MR imaging added information in the initial and follow-up clinical evaluation of these patients.