Fat-suppressed T2-weighted Spin-echo Research Articles

Assessment of knee joint synovitis at ultra-high field (7T) MRI: a multi-dimensional approach using contrast-enhanced and non-enhanced sequences

Purpose: With clearance for clinical use recently, 7T systems are already used clinically and will potentially become more widely available. MRI has made an important clinical impact in the assessment of inflammatory arthritis and osteoarthritis in the last decade. However, to date no clinical studies are available that have assessed the feasibility of 7T MRI for evaluation of inflammatory structural features of arthritis. Recommended imaging protocols on standard 1.5T and 3T systems include T1- and T2-weighted fat suppressed spin echo sequences and the use of contrast-enhanced (CE) MRI for the evaluation of synovitis.

Iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) of the wrist and finger at 3T: Comparison with chemical shift selective fat suppression images

To compare fat-suppressed magnetic resonance imaging (MRI) quality using iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) with that using chemical shift selective fat-suppressed T1-weighted spin-echo (CHESS) images for evaluating rheumatoid arthritis (RA) lesions of the hand and finger at 3T. MRI was performed in eight healthy volunteers and eight RA patients with a 3.0T MR system (Signa HDxt GE healthcare) using an eight-channel knee coil. FS-CHESS-T1-SE and IDEAL imaging were acquired in the coronal planes covering the entire structure of the bilateral hands with a slice thickness of 2 mm. In the RA patients both images were obtained after intravenous gadolinium administration. Image quality was evaluated on a five-point scale (1 = excellent to 5 = very poor). Synovitis and bone marrow contrast uptake on MR images were reviewed by two musculoskeletal radiologists using the Rheumatoid Arthritis MRI Scoring System (RAMRIS) of the Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) group. IDEAL showed uniform FS unaffected by magnetic field inhomogeneity and challenging geometry of hand and fingers, while CHESS-T1-SE often showed FS failure within the first metacarpal joint, tip of the finger, and ulnar aspect of the wrist joint. Overall image quality was significantly better with IDEAL than CHESS-T1-SE images (4.43 vs. 3.43, P < 0.01). Interobserver agreement (κ value) for synovitis and bone marrow contrast uptake was good to excellent with IDEAL (0.74-0.91, 0.62-0.89, respectively). IDEAL could compensate for the effects of field inhomogeneities, providing uniform FS of the hand and finger than did the CHESS-T1-SE sequence.

Magnetic Resonance for Quantitative Assessment of Liver Steatosis: A New Potential Tool to Monitor Antiretroviral-Drug-Related Toxicities

There is an increasing need for new diagnostic tools to monitor antiretroviral drug-related toxicities. Magnetic resonance (MR) imaging and MR spectroscopy are non-invasive diagnostic methods used in the detection and quantification of liver fat. The aim of this study was to compare sensitivity and specificity of different MR techniques in the quantitative assessment of liver steatosis, using liver biopsy as the reference standard, in patients with and without HIV infection. Sequentially evaluated patients with suspected steatosis who were referred for liver biopsy at our tertiary care site were eligible. MR liver fat content (LFC) was estimated by T2-weighted and fat-suppressed T2-weighted spin-echo, dual-phase T1-weighted gradient-echo, multiecho gradient-echo and (1)H spectroscopy. Association between LFC and histological steatosis percentage was calculated by using univariate linear regressions and Pearson's coefficient. Respective receiver operating characteristic (ROC) curves were used to compare specificity and sensitivity of MR methods in diagnosis (cutoff 5%) and in quantitative evaluation (cutoff 33%) of steatosis. A total of 28 patients were identified: 12 refused or had contraindications for liver biopsy and 16 had biopsies plus MR. LFC and histological steatosis percentage were strongly associated (fat-suppressed r=0.86 [P<0.001], dual-phase r=0.88 [P<0.001], multiecho r=0.95 [P<0,001] and spectroscopy r=0.84 [P=0.01]). MR techniques had high sensitivity and specificity in diagnosis and quantitative assessment of steatosis (areas under ROC curves ranging from 0.88 to 0.98). This pilot study confirms that MR may be a sensitive non-invasive alternative to biopsy for the quantitative assessment of liver fat and a potential end point to monitor antiretroviral-drug-related toxicities.

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.

Osteosarcoma

We sought to evaluate diffusion and perfusion weighted 1.5 T magnetic resonance imaging (MRI) in detecting tumor necrosis with histologic correlation after preoperative chemotherapy. Eight patients (ages 11-19 years) with histologic proven osteosarcoma of the limbs underwent T1- and fat-suppressed T2-weighted spin echo and diffusion-weighted EPI sequences (b value = 700) after 5 cycles of standard chemotherapy. Tumor volume and apparent diffusion coefficients (ADC) were calculated. Tumor signal intensities were measured in dynamic contrast enhanced T1-weighted fast gradient echo-sequences obtained every 3 seconds after an intravenous injection of gadolinium-DTPA. Perfusion parameters of first-pass tracing of contrast medium (time-to-peak, slope of contrast enhancement curve) were calculated, and perfusion maps were established. After MRI, all patients underwent limb resection, and the specimens were investigated macroscopically and histologically. The degree of tumor necrosis was assessed using the histologic Salzer-Kuntschik classification (grades 1-6) after chemotherapy. Necrotic areas, which were confirmed by macroscopic/histologic examination, showed ADC values up to 2.7 (mean, 2.3 +/- 0.2). Viable tumor areas revealed lower apparent diffusion coefficients (mean, 0.8 +/- 0.3). The differences in ADC between viable and necrotic tumor were highly significant (paired t test; P = 0.01). Slopes of necrotic areas ranged from 0.1 up to 5.2%/min (mean, 1.5%/min) and those of viable tumor areas from 2.8 to 31.5%/min (mean, 16.1%/min). The time-to-peak-values (TTPs) ranged from 40 to 210 seconds (mean, 131 seconds, SD 60 seconds) in necrotic tumors and from 30 to 96 seconds (mean, 55 seconds, SD 21) in viable areas of sarcomas. The differences in slope and TTP between viable and necrotic tumor were highly significant. In necrotic areas, the linear correlation between slope (%/min) and ADC (mm/s) and between TTP (s) and ADC were weak, respectively. Both dynamic contrast-enhanced MRI and diffusion-weighted MRI permit recognition of tumor necrosis induced by chemotherapy in osteosarcomas. We hypothesized that diffusion-weighted imaging is correlated directly with tumor necrosis. Perfusion-weighted imaging is correlated with microvessel density, vascular permeability, local blood volume, and flow. Therefore, perfusion weighed MRI depicts areas of tumor cell necrosis indirectly.

Lateral ulnar collateral ligament of the elbow: optimization of evaluation with two-dimensional MR imaging.

To compare, in a cadaveric model, magnetic resonance (MR) imaging techniques with differing contrast and spatial resolution properties in the evaluation of disruption of the lateral ulnar collateral ligament (LUCL) at the elbow. LUCL tears were surgically created in eight of 28 cadaveric elbow specimens. All specimens underwent 1.5-T MR imaging with the following pulse sequences: T1-weighted spin echo (SE), intermediate-weighted fast SE, fat-suppressed T2-weighted fast SE, gradient-recalled echo (GRE) with high spatial resolution, intermediate-weighted fast SE with high spatial resolution, and fat-suppressed T1-weighted SE with intraarticular administration of gadopentetate dimeglumine (MR arthrography). All images were obtained in the oblique coronal plane. Two radiologists independently graded the LUCL with separate and side-by-side assessment. Areas under the receiver operating characteristic curve were as follows for readers A and B, respectively: T1-weighted SE imaging, 0.64 and 0.62; intermediate-weighted fast SE imaging, 0.87 and 0.67; T2-weighted fast SE imaging, 0.68 and 0.69; GRE imaging, 0.56 and 0.68; MR arthrography, 0.84 and 0.85; and intermediate-weighted imaging with high spatial resolution, 0.92 and 0.88. Interobserver reliability was poor with T1-weighted SE imaging (kappa = 0.13) and GRE imaging (kappa = 0.18), fair with T2-weighted fast SE imaging (kappa = 0.36), and moderate with MR arthrography (kappa = 0.46), intermediate-weighted fast SE imaging (kappa = 0.55), and intermediate-weighted imaging with high spatial resolution (kappa = 0.59). Intermediate-weighted imaging with high spatial resolution and MR arthrography showed the greatest overall ability to enable the diagnosis of LUCL tears.

Severity of synovium and bone marrow abnormalities of the temporomandibular joint in early rheumatoid arthritis: role of gadolinium-enhanced fat-suppressed T1-weighted spin echo MRI.

Our goal was to evaluate the efficacy of dynamic contrast-enhanced fat-suppressed MRI of the temporomandibular joint (TMJ) in detecting early joint involvement in patients with rheumatoid arthritis (RA). Conventional T1- and T2-weighted, gadolinium-enhanced T1-weighted, and dynamic gadolinium-enhanced fat-suppressed SE imaging sequences were performed in 22 patients with RA. The dynamic gadolinium-enhanced fat-suppressed T1-weighted SE sequence was more sensitive than the other techniques in detecting early changes in inflamed synovium of periarticular tissue and in detecting condylar bone marrow involvement. In patients with RA, 17 joints with joint pain showed synovial proliferation in 10 (59%) cases and joint effusion in 4 (24%). Of 14 joints with joint sound, 4 (29%) showed synovial proliferation and 7 (50%) showed joint effusion. A lower positional change of the disk was observed in joints with RA than in those with TMJ disorders (82 patients). Gadolinium-enhanced fat-suppressed MRI was extremely effective in diagnosing early changes of the inflamed TMJ.

Diagnosis of adrenal adenoma: Value of central spot of high‐intensity hyperintense rim sign and homogeneous isointensity to liver on gadolinium‐enhanced fat‐suppressed spin‐echo MR images

Eighty-nine patients with 108 adrenal masses, either adenomas (n = 88) or malignant lesions (n = 20), underwent magnetic resonance imaging (MRI) of the abdomen at 0.5 T for the purpose of determining whether adrenal adenomas could be differentiated from malignant lesions on gadolinium-enhanced fat-suppressed T1-weighted spin-echo (SE) images (Gd-E FS T1WI) and on T2-weighted SE images. The imaging protocol included conventional unenhanced SE T1- and T2-weighted sequences and Gd-E FS T1WI. Three observers independently evaluated signal intensity on unenhanced and enhanced images and also the presence of structures of high signal intensity in the outer margin [hyperintense rim sign (HRS)] or in the center [hyperintense central spot (HCS)] of the adrenal masses. Forty-one (46.5%) of 88 adenomas were homogeneously isointense to liver in unenhanced and enhanced T1-weighted sequences and in T2WI. HCS and HRS were observed in 33/88 (37.5%) and 15/88 (17%) adenomas, respectively, on Gd-E FS T1WI; in contrast, these signs were never revealed in any case of malignant lesions. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy in classifying lesions as suggestive of adenoma were 93%, 90%, 98%, 75%, and 93%, respectively. Visual evaluation of details of tumor structures on Gd-E FS T1WI allows good characterization of adrenal masses. HCS, HRS, and homogeneous isointensity to liver are characteristic signs of adrenal adenomas. J. Magn. Reson. Imaging 1999; 9:304–310. © 1999 Wiley-Liss, Inc.

Diagnosis of adrenal adenoma: value of central spot of high-intensity hyperintense rim sign and homogeneous isointensity to liver on gadolinium-enhanced fat-suppressed spin-echo MR images.

Eighty-nine patients with 108 adrenal masses, either adenomas (n = 88) or malignant lesions (n = 20), underwent magnetic resonance imaging (MRI) of the abdomen at 0.5 T for the purpose of determining whether adrenal adenomas could be differentiated from malignant lesions on gadolinium-enhanced fat-suppressed T1-weighted spin-echo (SE) images (Gd-E FS T1WI) and on T2-weighted SE images. The imaging protocol included conventional unenhanced SE T1- and T2-weighted sequences and Gd-E FS T1WI. Three observers independently evaluated signal intensity on unenhanced and enhanced images and also the presence of structures of high signal intensity in the outer margin [hyperintense rim sign (HRS)] or in the center [hyperintense central spot (HCS)] of the adrenal masses. Forty-one (46.5%) of 88 adenomas were homogeneously isointense to liver in unenhanced and enhanced T1-weighted sequences and in T2WI. HCS and HRS were observed in 33/88 (37.5%) and 15/88 (17%) adenomas, respectively, on Gd-E FS T1WI; in contrast, these signs were never revealed in any case of malignant lesions. Sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy in classifying lesions as suggestive of adenoma were 93%, 90%, 98%, 75%, and 93%, respectively. Visual evaluation of details of tumor structures on Gd-E FS T1WI allows good characterization of adrenal masses. HCS, HRS, and homogeneous isointensity to liver are characteristic signs of adrenal adenomas.

Malignant hepatic tumors: changes on MRI after hepatic arterial chemoembolization--preliminary findings.

This study describes the MR appearances of malignant hypervascular liver lesions pre- and post-hepatic-arterial chemoembolization, with correlation to serial imaging and clinical responses. Eight patients with malignant hypervascular liver lesions underwent pretreatment and posttreatment MR examination on a 1.5-T MR imager. MR sequences included T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed spin echo or turbo spin echo, and dynamic gadolinium-enhanced SGE images. All patients underwent pretreatment, initial posttreatment, and subsequent posttreatment MR studies. The histology of primary tumors included various types of hepatocellular carcinoma (HCC) (four patients: fibrolamellar HCC [one patient], HCC [two patients], mixed HCC/cholangiocarcinoma [one patient]) and liver metastases (four patients: untyped islet cell tumor [two patients], gastrinoma [one patient], carcinoid [one patient]). Response to chemoembolization was determined by three assessments: MR response, serial imaging response, and clinical response. The appearance of MR response to chemoembolization was determined based on the correlation with clinical and serial imaging response. The MR response of lesions that showed good clinical response included: increase in signal intensity on T1-weighted images (three patients), decrease in signal intensity on T2-weighted images (three patients), and negligible or minimal enhancement on immediate postgadolinium images (four patients) after chemoembolization. The most marked change in lesion appearance was observed in lesions < or = 1 cm, which had intense homogeneous enhancement on pretreatment MR studies and negligible enhancement on initial posttreatment MR examinations. MR response of lesions that showed moderate clinical response demonstrated a variety of lesion appearances from substantial change to minimal change. MR response of lesions that showed poor clinical response demonstrated no change in lesion appearances compared with the pretreatment MR study. Our results demonstrated change in appearance of liver lesions between pre- and post-hepatic-arterial chemoembolization MR studies. MR response correlated with response determined by serial imaging studies and clinical findings.

Pancreatic masses with inconclusive findings on spiral CT: is there a role for MRI?

This prospective study evaluates the ability of MRI using T1-weighted fat-suppressed spin-echo (T1FS) and dynamic gadolinium chelate (Gd) enhanced spoiled-gradient echo (SGE) to detect the presence of pancreatic tumor in patients in whom spiral CT findings are inconclusive. Sixteen consecutive patients who underwent spiral CT and had findings that were considered inconclusive for pancreatic tumor underwent MR within 2 weeks of CT. Spiral CT and MR images were interpreted in prospective fashion by separate individual investigators blinded to the results of the other imaging modality. CT was performed on a spiral CT scanner. MRI was performed on on a 1.5-T MR machine. Imaging sequences included T1FS pre-Gd and post-Gd and SGE pre-Gd and immediately post-Gd. Data were analyzed using receiver operating characteristic (ROC) analysis. Confirmation was obtained by pancreatic biopsy (n = 4), surgical resection (n = 1), and clinical imaging (n = 4) or clinical follow-up (n = 7). MRI was superior to spiral CT (P = .027) in this selected patient group at detecting or excluding pancreatic tumor by ROC analysis, with areas under the curve of .982 and .764, respectively, which was significant (P = .041). The greatest advantage of MRI was in patients in whom spiral CT demonstrated enlargement of the pancreatic head without clear definition of tumor, which was significant (P = .033). In 10 patients with this CT appearance, MRI demonstrated a high confidence for presence of tumor in four and a high confidence of absence in six. Association of imaging findings with patient diagnosis was significant for MRI (P = .001) but not significant for CT (P = .148). The results of our study suggest that MRI may add significant diagnostic information in patients in whom spiral CT is inconclusive for the presence of pancreatic tumor. The greatest advantage of MRI was in the evaluation of patients in whom spiral CT findings revealed an indeterminate enlarged pancreatic head.

Mn-DPDP enhanced MR imaging of the liver: Analysis of pulse sequence performance

Aim: To compare liver enhancement and lesion-liver contrast on T1-weighted (T1W) gradient recalled echo (GRE), spin-echo (SE) and fat-suppressed SE (FS-SE) pulse sequences at Manganese-DPDP (Mn-DPDP) enhanced magnetic resonance (MR) imaging of the liver. Patients and Methods: Twenty-one patients with known liver lesions were administered 5 μmol/kg of Mn-DPDP. TIW GRE (78/2.3/80°), SE and F-SE (300/12) images were obtained before and 15min after Mn-DPDP. Signal/noise ratio (SNR) and lesion-liver contrast/noise ratio (CNR) were calculated for each pulse sequence. Results: Liver SNR ( n = 21) and lesion-liver CNR ( n = 10) increased significantly after Mn-DPDP on all three pulse sequences ( P < 0.0001). Liver SNR was highest on the FS-SE and GRE pulse sequences (FS-SE = 43.8, GRE = 38.4, SE = 29.2). Lesion-liver CNR was highest on the FS-SE pulse sequence (FS-SE = −29.3, SE = −23.2, GRE = −19.8), which was significantly higher than the GRE pulse sequence ( P < 0.05). Conclusion: The T1-weighted fat-suppressed SE (FS-SE) pulse sequence provides highest liver enhancement and lesion-liver contrast and is recommended for Mn-DPDP enhanced MR imaging.

Transitional cell carcinoma of the upper urinary tract: staging by MRI.

This study evaluates the ability of MRI to stage transitional cell carcinoma of the upper urinary tract. Nine patients who had transitional cell carcinoma of the upper urinary tract detected by other imaging modalities underwent MRI examination at 1.5 T. Imaging included pre- and postgadolinium-DTPA T1-weighted images (9 patients) pre- and postgadolinium chelate T1-weighted fat-suppressed spin echo (7 patients). Postcontrast images were acquired prior to the presence of gadolinium within the collecting system (< 2 min postcontrast), intermediate (2.5-8 min), and late (> 10 min) postcontrast. Images were prospectively interpreted and lesion staging was determined. Correlation with histopathology was obtained in all cases. Transitional cell cancers were demonstrated in 9/9 patients, and tumors ranged in size from 2 to 8 cm (mean = 3.8 cm) in one dimension. Correct tumor staging was performed in 8/9 patients. The staging error in one case occurred because direct tumor extension into the renal parenchyma was not detected. The results of this preliminary study show that MRI stages transitional cell cancers relatively well; however, MRI is not able to detect superficial invasion of renal parenchyma.

Adrenocortical carcinoma: MR imaging appearance with current techniques.

The purpose of the study was to define the magnetic resonance (MR) imaging appearance of adrenocortical carcinoma (ACC) with current MR techniques. Eight patients with ACC underwent high-field-strength MR imaging with the following sequences: axial T1-weighted gradient echo, fat-suppressed T1-weighted spin echo, fat-suppressed T2-weighted spin echo, and gadolinium-enhanced T1-weighted gradient echo and fat-suppressed T1-weighted spin echo. Postcontrast images were also acquired in the sagittal (six patients) and coronal (three patients) planes. Out-of-phase gradient-echo images were obtained in two patients. Lesion morphology, signal intensity features, and presence of metastatic disease were retrospectively evaluated. MR imaging features of ACC included internal hemorrhage (seven of eight patients), central necrosis (seven of eight), and peripheral enhancing nodules (seven of eight). Out-of-phase images in two of two patients demonstrated signal loss compared with in-phase images, which may be a common feature of these tumors. Liver metastases were present in four patients. Consistent MR features of ACC are identified.

Magnetic Resonance Imaging of the Spleen and Pancreas

MRI of the spleen and pancreas requires specialized sequences which diminish artifacts in the upper abdomen. High temporal resolution sequences (e.g., spoiled gradient echo) acquired immediately after intravenous Gd-DTPA administration are necessary for imaging both the spleen and pancreas. In evaluating the spleen, early post Gd-DTPA images are essential as many focal disease processes (e.g., lymphomatous deposits or metastases) equilibrate rapidly (< 2 min) with splenic parenchyma. Complete pancreatic examination also requires the use of T1-weighted fat suppressed spin echo. T2-weighted images provide complementary information in a number of settings, in particular in the evaluation of islet cell tumors. Pancreatic ductal carcinoma is low signal on T1-weighted images and enhances in a diminished fashion on immediate post Gd-DTPA images. These tumors are well differentiated from focal chronic pancreatitis and islet celltumors based on their appearances on combined T1, T2-weighted and immediate post Gd-DTPA enhanced images.

Magnetic Resonance Imaging of the Liver

A variety of diffuse and focal disease processes affect the liver. MRI is likely the imaging modality of choice for investigation of patients suspected of having diffuse disease such as cirrhosis, hemochromatosis, or fatty infiltration. MRI is extremely effective at detecting and characterizing focal hepatic lesions. In particular, patients suspected of possessing hemangiomas, hepatocellular carcinoma, or hypervascular liver metastases are better evaluated by MRI than other imaging modalities. Immediate post gadolinium spoiled gradient echo and T2-weighted fat suppressed spin echo are very effective at lesion detection, whereas serial post gadolinium spoiled gradient echo is essential for lesion characterization. New fast T2-weighted sequences and tissue specific contrast agents may further increase the role of liver MRI by shortening exam time and increasing sensitivity and specificity, respectively.

Comparison of Magnetic Resonance Imaging and Endoscopy in Distinguishing the Type and Severity of Inflammatory Bowel Disease

Twenty consecutive patients with first-time presentation of suspected inflammatory bowel disease underwent both endoscopy with biopsy and magnetic resonance imaging (MRI) within a 3-day period; the relative abilities of endoscopy and MRI to distinguish ulcerative colitis (UC) from Crohn's disease (CD) and to determine the severity of the disease process were compared. In 18 of 20 patients, a diagnosis of UC or CD could be made on histological specimens. MRI correctly diagnosed 17 of these 18 patients using T1-weighted fat-suppressed spin echo and gadolinium enhancement. Endoscopy correctly diagnosed 15 patients. Overall, MRI was not significantly better (p > 0.05) than endoscopy in distinguishing UC from CD. MRI correctly graded the severity of inflammatory changes in 13 of 20 patients, and endoscopy did so in 11 of 20. MRI and endoscopy findings were within one grade of histology findings in seven patients each. No significant difference (p > 0.05) was found between MRI and endoscopy in the ability to estimate the severity of the disease (as determined from biopsies). Bowel wall thickness measured on MR images demonstrated good correlation with percentage of contrast enhancement: r = 0.61; p = 0.003. In sum, magnetic resonance imaging was shown to be comparable with endoscopy in differentiating UC from CD and in gauging the severity of disease. Transmural assessment, sagittal imaging, and the lack of invasiveness were attractive features of MRI.

Renal corticomedullary differentiation: observation in patients with differing serum creatinine levels.

To evaluate renal corticomedullary differentiation (CMD) in patients with differing serum creatinine (sCr) levels. Ten patients with normal sCr levels (0.9-1.3 mg/dL [80-115 mumol/L]), 14 with mildly elevated levels (1.5-2.9 mg/dL [133-256 mumol/L]), and 15 with elevated levels (> 3.0 mg/dL [265 mumol/L]) were examined with unenhanced T1-weighted fat-suppressed spin-echo (T1FS) and immediate gadolinium-enhanced gradient-echo (Gd-GRE) imaging. Patients with normal sCr levels had CMD on T1FS and Gd-GRE images. Among patients with mildly elevated levels, seven did and seven did not have CMD on T1FS images; all had CMD on Gd-GRE images. Patients with elevated levels had no CMD on T1FS images; 13 had CMD on Gd-GRE images. Two patients with levels above 10.0 mg/dL (884 mumol/L) had no CMD on Gd-GRE images. Independent of the cause of elevated sCr level, levels above 3.0 mg/dL result in loss of CMD on T1FS images, while levels above 10.0 mg/dL result in loss of CMD on Gd-GRE images.

MRI in the Diagnosis of Crohnʼs Disease in Two Pregnant Women

Two pregnant women considered symptomatic for inflammatory bowel disease were referred for magnetic resonance imaging (MRI) for assistance in establishing a diagnosis. Breath-hold gradient echo and contrast-enhanced T1-weighted fat-suppressed spin echo sequences were used. The MR appearance of the terminal ileum was consistent with Crohn's disease in both patients. The diagnosis of Crohn's disease was subsequently confirmed histologically. MRI is a safe, noninvasive modality that may be useful in confirming a suspected diagnosis of inflammatory bowel disease, especially in patients who cannot be evaluated with standard techniques.

Focal liver disease: comparison of dynamic contrast-enhanced CT and T2-weighted fat-suppressed, FLASH, and dynamic gadolinium-enhanced MR imaging at 1.5 T.

Dynamic contrast medium-enhanced computed tomography (CT), T2-weighted fat-suppressed spin-echo (T2FS) magnetic resonance (MR) imaging, and breath-hold T1-weighted fast low-angle shot (FLASH) MR imaging before and after dynamic gadopentetate dimeglumine injection were compared in 73 patients with clinically suspected liver disease. Observer confidence for presence of focal lesions was determined by using receiver operating characteristic analysis. For all MR images, hepatic lesion-liver signal-to-noise ratios were evaluated qualitatively. and resolution and presence of artifacts were evaluated qualitatively. Lesion detection was greatest with T2FS (n = 272) and enhanced FLASH (n = 244) and was statistically greater with both of these than with CT (n = 220) and FLASH (n = 219) (P less than .03). Correct lesion characterization was greatest with enhanced FLASH (n = 236) (P less than .01), followed by CT (n = 199), FLASH (n = 164), and T2FS (n = 144). Enhanced FLASH was particularly successful in characterization of 5-mm- to 1.5-cm-diameter lesions as cystic or solid.