Evaluation of turbo spin echo sequences for MRI of focal liver lesions at 0.5 T

To determine whether turbo spin echo (TSE) sequences can replace conventional T2-weighted spin echo (SE) sequences in MRI of the liver, 40 patients with focal liver lesions were imaged at 0.5 T. A T2-weighted SE sequences (TR/TE 1800/90 ms, number of signals averaged [NEX]=2, scan time=7:16 min), a TSE sequence (TR/TE 1800/90 ms, NEX=4, number of echos per excitation=13, echo spacing=12.9 ms, scan time=4:16 min) and a T1-weighted SE sequence (TR/TE 350/15 ms, NEX=2, scan time=4:21 min) were obtained and image quality, lesion detectability and lesion differentiation were evaluated qualitatively by subjective assessment using scores and quantitatively by lesion-liver contrast-to-noise (CNR) and tumour/liver signal intensity (SI) ratios. The image quality of the TSE sequence was substantially better compared with the T2-weighted SE sequence due to a reduction in motion artefacts and better delineation of anatomical details. Of a total of 158 visible lesions the T1-weighted SE, TSE, and T2-weighted SE sequences showed 91%, 81% and 65% of the lesions, respectively. Thus the TSE sequence depicted 24% (P< 0.001) more lesions than the T2-weighted SE sequence. In all types of pathology the lesion-liver CNR of the TSE sequence was significantly (P< 0.001) higher compared to the CNR of the T2-weighted SE sequence (+ 55–65%), indicating superior lesion conspicuity. Lesion characterization was equally good on the two T2-weighted sequences with no difference in the tumour/liver SI ratio. Using a criterion of tumour/liver SI ratio equal to or higher than 2, haemangiomas larger than 1 cm in diameter could be differentiated from other lesions with a sensitivity and specificity of 95% and 96%, respectively. Our results indicate that the TSE sequence is suitable for replacing the conventional T2-weighted SE sequence in MRI of focal liver lesions.This paper was presented at ECR 1993 Correspondence to: B. Kreft     

MRI during fast infusion of Gd-DTPA: results in hepatic and pancreatic enhancement

The authors describe the results obtained with dynamic MRI of the parenchymal organs during the infusion of contrast agents. Thirteen patients with hepatic and pancreatic lesions were studied. RASE sequences were characterized by TR of 260 ms, TE of 16 ms, NEX 1, matrix 128 × 256. Infusion of the contrast agent started 15 s prior to the beginning of the pulse sequence and continued throughout the pulse sequence (25 s). In this way, a continuous inflow of contrast agent in abdominal organs was expected during the acquisition time. The conventional dose of Gd-DTPA was employed (0.1 mmol/kg).The results demonstrate a highly relevant pancreatic enhancement in the early arterial phase of perfusion, with values of SE/N of 18.1 versus 8.5 in the subsequent sequence. However, in the liver the perfusion study did not improve the parenchymal enhancement, with values of 9.3 versus 15.3 in the late phase. There was no improvement of hypontense lesion detections in the liver, while the hypervascular lesions were visualized with a high signal intensity in the early perfusion study, disappearing in the later sequences. Correspondence to: P. Pavone     

眼眶磁共振成像技术的研究

目的探讨眼眶磁共振扫描成像技术。方法采用GE1.5TsignaEchospeed或GE1.5TsignaTwinspeed,对30例患者做眼眶磁共振成像(MagneticResonanceImaging)。脉冲序列:SET1加权(weightedImagingWI),FSET2加权(weightedImagingWI),T2WI采用脂肪抑制技术或SET1flair,FRFSET2WIT2WI采用脂肪抑制技术。扫描方位:横轴位(Axial)、冠状位(Coronal)、矢状斜位(ObliqueSagittal)和横轴俯卧位(prone)等。扫描参数:Fov18cm×18cm,SET1WI:TR440msTE11ms,FSET2WI:TR3000msTE98ms或T1flair:TR2143ms,TE11ms,TI750ms,FRFSET2WI:TR3500msTE80ms,矩阵256×256,接收带宽15.63MHz,平均激励次数4次,层厚3～4mm,无间隔。增强对比剂用GdDTPA0.1mmolkg。结果横轴位可清晰显示视神经全长及眼内外直肌及与病变的关系。冠状位在同一层面可清晰显示视神经、眼内外直肌、眼上下直肌的断面及与病变的关系。矢状斜位可清晰显示视神经全长、眼上下直肌及与病变的关系。结论磁共振扫描参数的优化组合和选择正确的扫描方位,及T2WI脂肪抑制技术等的应用更有助于显示正常眼眶解剖结构及眼眶病变的定位和诊断。     

High-resolution magnetic resonance angiography of the internal carotid artery: 2D vs 3D TOF in stenotic disease

The aim of this study was to compare high-resolution 2D TOF with high-resolution 3D TOF in the study of internal carotid artery disease. Sixty-four patients with clinical signs of cerebrovascular insufficiency were studied with a superconductive 1.5 T magnet using two techniques: 2D and 3D TOF. Digital subtraction angiography (DSA) was the gold standard. The 2D TOF technique was performed using the following parameters: TR/TE/FA/MA 49 ms/9 ms/60°/512 × 256; the 3D TOF was performed with the following parameters: TR/TE/FA/MA 50 ms/8 ms/20°/512 × 256. The 2D TOF agreed with DSA in 116 of 128 diagnostic judgments (90 %) and overestimated seven times. The 3D TOF technique agreed with DSA in 125 of 128 diagnostic judgments (97 %) with one overestimation and two underestimations. There was no statistically significant difference (P < 0.05) between the two different techniques. Our study confirms the high reliability of the methodology carried out with the high-resolution 2D and 3D technique. Received 12 September 1997; Revision received 18 December 1997; Accepted 19 December 1997     

T1-weighted spoiled gradient-echo MR imaging of focal hepatic lesion: comparison of in-phase vs opposed-phase pulse sequence

The goal of our prospective study was to compare quantitatively and qualitatively in-phase and opposed-phase T1-weighted breath-hold spoiled gradient-recalled-echo (GRE) MR imaging technique for imaging focal hepatic lesion. Thirty-eight patients with 53 focal hepatic lesions had in-phase (TR = 12.3 ms, TE = 4.2 ms) and opposed-phase (TR = 10.1 ms, TE = 1.9 ms) GRE (flip angle = 30°, bandwidth ± 32 kHz, matrix size 256 × 128, one signal average) MR imaging at 1.5 T. Images were analyzed quantitatively by measuring the lesion-to-liver contrast and for lesion detection. In addition, images were reviewed qualitatively for lesion conspicuity. Quantitatively, lesion-to-liver contrast obtained with in-phase (3.22 ± 1.86) and opposed-phase pulse sequence (3.72 ± 2.32) were not statistically different (Student's t-test). No difference in sensitivity was found between in-phase and opposed-phase pulse sequence (31 of 53, sensitivity 58 % vs 30 of 53, sensitivity 57 %, respectively). Two lesions not seen with opposed-phase imaging were detected with in-phase imaging. Conversely, one lesion not seen on in-phase imaging was detected on opposed-phase imaging so that the combination of in-phase and opposed-phase imaging yielded detection of 32 of 53 lesions (sensitivity 60 %). Qualitatively, lesion conspicuity was similar with both techniques. However, in-phase images showed better lesion conspicuity than opposed-phase images in 9 cases, and opposed-phase images showed better lesion conspicuity than in-phase images in 7 cases. No definite advantage (at a significant level) emerged between in-phase and opposed-phase spoiled GRE imaging. Because differences in lesion conspicuity and lesion detection may be observed with the two techniques in individual cases, MR evaluation of patients with focal hepatic lesion should include both in-phase and opposed-phase spoiled GRE imaging. Received 30 October 1996; Revision received 6 January 1997; Accepted 8 January 1997     

Value of opposed-phase gradient-echo technique in distinguishing between benign and malignant vertebral lesions

Our objective was to evaluate the possible role of opposed-phase gradient-echo (GRE) sequence in predicting the nature of vertebral lesions supposing that in the case of malignancy fat is completely replaced while in the case of benign lesion fat is still present. Eighty-six patients with vertebral lesions underwent MR examination at 0.5 T. The MR protocol included a T1-weighted spin-echo (SE) and an opposed-phase GRE using the same parameters (TR=280-320 ms, flip angle=90 degrees, slice thickness=3.5-4 mm, matrix=256x160-192, field of view=34-36 cm, no. of excitations=2-4) except for TE (10 ms in SE vs 7 ms in GRE) to obtain opposed-phased images. Qualitative (nature of lesion, detectability, degree of signal intensity (SI), marrow pattern) and quantitative (SI on opposed-phase GRE minus SI on T1-weighted SE minus SI ratio=SI on out-of-phase GRE images divided by SI on T1-weighted SE images) analysis were performed. The SI ratio values were analysed using Mann-Whitney rank-sum test and receiver operating characteristics (ROC) curve. Lesions resulted to be malignant in 45 and benign in 41 patients (23 biopsies, 20 MR follow-ups, 43 clinical and other imaging follow-ups). Based on visual inspection of opposed-phased images, visual SI was evaluated high in 38 (34 malignant, 34 benign), mild in 28 (9 malignant, 19 benign) and low in 20 (2 malignant, 18 benign) patients. Based on region-of-interest measurements, SI ratio values range was 0.36-6.2 (mean value=1.68+/-0.82) for malignant and 0.07-1.54 (mean value=0.77+/-0.44) for benign lesions. A cut-off value of 1.2 gave a sensitivity, specificity, accuracy, negative predictive value and positive predictive value, respectively, of 88.8, 80.49, 84.88, 86.4 and 83.33%. The ROC analysis of the SI ratio showed an area under ROC curve of 0.92 and a statistically significant difference between the two groups of lesions was observed ( p<0.01). The GRE opposed-phase sequence can help to predict the nature of a vertebral lesion. This fast and widely available technique together with morphological criteria can improve the accuracy of MRI.     

Musculoskeletal MR imaging: turbo (fast) spin-echo versus conventional spin-echo and gradient-echo imaging at 0.5 tesla

The value of T2-weighted fast spin-echo imaging of the musculoskeletal system was assessed in 22 patients with various neoplastic, inflammatory, and traumatic disorders. Images were acquired with high echo number (i.e., echo train length) fast spin-echo (FSE; TR 2000 ms, effective TE 100 ms, echo number 13, lineark-space ordering), conventional spin-echo (SE; TR 2000 ms, TE 100 ms) and gradient-echo (GRE) sequences (TR 600 ms, TE 34 ms, flip angle 25°). Signal intensities, signal-to-noise ratios, contrast, contrast-to-noise ratios, lesion conspicuousness, detail perceptibility, and sensitivity towards image artifacts were compared. The high signal intensity of fat on FSE images resulted in a slightly inferior lesion-to-fat contrast on FSE images. However, on the basis of lesion conspicuity, FSE is able to replace time-consuming conventional T2-weighted SE imaging in musculoskeletal MRI. In contrast, GRE images frequently showed superior lesion conspicuity. One minor disadvantage of FSE in our study was the frequent deterioration of image quality by blurring, black band, and rippling artifacts. Some of these artifacts, however, can be prevented using short echo trains and/or short echo spacings.     

Magnetic resonance imaging of pancreatic carcinoma

The authors have used MRI for investigation of 41 patients with pancreatic tumours. MR examinations were performed with 0.5 T superconductive equipment. Short TR, short TE spin echo (SE) sequences were obtained with 8 averages and 256×256 matrix. T2-weighted sequences were also acquired. T1-weighted SE sequences provided more detail, with high intrinsic contrast between the tumour and the normal pancreas; small lesions (19 smaller than 3 cm in diameter) were always detected on these images. T2-weighted SE sequences were not useful for lesion detection, due to the lower intrinsic contrast and the number of artefacts. T2-weighted sequences proved helpful for lesion characterisation in two cases of cystoadenocarcinoma only. Staging of the tumour was possible with MRI, with good assessment of local spread, lymphoadenopathy, vascular involvement and hepatic metastases. MRI of the pancreas at medium field strength can be an alternative to CT in selected cases. Offprints requests to: P.Pavone     

Hyaline articular cartilage: relaxation times,pulse-sequence parameters and MR appearance at 1.5 T

In order to optimize the parameters for the best visualization of the internal architecture of the hyaline articular cartilage a study both ex vivo and in vivo was performed. Accurate T1 and T2 relaxation times of articular cartilage were obtained with a particular mixed sequence and then used for the creation of isocontrast intensity graphs. These graphs subsequently allowed in all pulse sequences (spin echo, SE and gradient time (TR), echo time (TE) and flip angle (FA) for optimization of signal differences between MR cartilage zones. For SE sequences maximum contrast between cartilage zones can be obtained by using a long TR (> 1,500 ms) with a short TE (< 30 ms), whereas for GRE sequences maximum contrast is obtained with th shortest TE (< 15 ms) combined with a relatively long TR (> 400 ms) and an FA greater than 40°. A trilaminar appearance was demonstrated with a superficial and deep hypointense ozne in all sequences and an intermediate zone that was moderately hyperintense on SET1-weighted images, slightly more hyperintense on proton density Rho and SE T2-weighted images and even more hyperintense on GRE images.     

MRI gadolinium enhancement of bone marrow: age-related changes in normals and in diffuse neoplastic infiltration

 Objective: To quantify gadolinium-related enhancement in the bone marrow of the spine in normals and in patients with homogeneous diffuse malignant bone marrow infiltration. Design and patients: The patients consisted of two groups: group 1 comprised 94 healthy adults (18–86 years) without bone marrow disease and group 2 comprised 30 patients with homogeneous diffuse malignant bone marrow infiltration due to myeloma (n=20) or breast carcinoma (n=10). All patients received intravenous gadopentetate dimeglumine (Gd-DTPA), 0.1 mmol/kg body weight. Pre- and postcontrast signal intensity (SI) on T1-weighted spin-echo (SE) images (TR/TE: 572 ms/15 ms) was measured over a region of interest (ROI) and the percentage SI increase was calculated. The results were confirmed by bone marrow biopsy (n=20) and clinical parameters (n=10). Dynamic contrast-enhanced studies using a spoiled gradient-recalled-echo (GRE) sequence (TR/TE/α: 68 ms/6 ms 75°) were performed in 10 controls with normal bone marrow. Results and conclusion: Contrast material enhancement in healthy persons can vary greatly (range 3–59%, mean 21%, SD 11%). With increasing age there is a significant decrease in contrast enhancement (Pearson’s correlation, P<0.01). The percentage SI increase in patients with intermediate-grade (biopsy 20–50 vol%) and high-grade (biopsy >50 vol%) diffuse malignant bone marrow infiltration was significantly higher than in normals (mean 67%, SD 34%, P<0.001). Low-grade (biopsy <20 vol%) diffuse malignant bone marrow infiltration can not be assessed by non-enhanced T1-weighted SE images or Gd-DTPA application. In conclusion, contrast material enhancement in healthy persons can vary greatly and is dependent on age, while intermediate-grade and high-grade diffuse malignant bone marrow infiltration can be objectively assessed with SI measurements.     

Contrast media in MR arthrography of the glenohumeral joint: intra-articular gadopentetate vs saline: preliminary results

The purpose of this investigation was to compare gadopentetate and saline as contrast media in MR arthrograms of the glenohumeral joint. In 60 consecutive patients MR arthrograms with either gadopentetate (n = 26) or saline (n = 34) were performed. After injection of gadopentate, 3D gradient-echo (GE) images were obtained (TR 32 ms, TE 10 ms, flip angle 40 °). With saline, double-echo steady-state images (heavily T2-weighted 3D GE images) were obtained (TR 40 ms, TE 9/45 ms, flip angle 40 °). In the last 14 of these patients T2-weighted turbo spin-echo (SE) images were added (TR 2900 ms, TE 96 ms). Contrast-to-noise ratios standardized for imaging times proved to be superior for the gadolinium arthrograms compared with GE and SE saline arthrograms (intra-articular fluid vs subacromial fat: p = 0.0001 and 0.0008; intra-articular fluid vs supraspinatus tendon: p = 0.0001 and 0.046). Using a qualitative scoring system gadolinium arthrograms were superior to saline arthrograms (p < 0.0001 and p < 0.0001). Saline arthrograms in combination with GE and SE sequences are inferior to gadopentetate arthrograms with GE sequences. Received 24 May 1996; Accepted 30 August 1996     

Time-reduced T2-weighted celebral MRI with optimized flip angles

This study was set up to see whether lowering the flip angle in proton density- and T2-weighted double-spin echo sequences allows for shortening of repetition time (TR) and imaging time without significant change of image quality. Ten patients with celebral white matter lesions were investigated with an 1.5 T MR scanner using a conventional long- TR double-spin echo sequence (TR = 2500 ms, TE = 15 and 70 ms) and reduced-TR double-spin echo sequences (TR = 1900 ms, TE = 15 and 70 ms) at flip angles of 90°, 80°, 70°, 60°, and 50°. Lowering the flip angle resulted in less T1-contrast and a relative increase of T2-contrast. At a flip angle of 70°, contrast-to noise ratios (NNRs) between lesions and brain, as well as image artifacts of the reduced-TR sequence (CNR: 22.4) were similar to the conventional long-TR sequence (CNR:21.1), while imaging time was shortened by about 25%. Offprint requests to: Peter Schubeus     

Selective water excitation for faster MR imaging of articular cartilage defects: initial clinical results

Our objective was to compare a water-excitation (WE) 3D fast low-angle shot (FLASH) MR sequence for faster imaging of articular cartilage defects of the knee to a conventional fat-saturated (FS) 3D FLASH MR sequence. This prospective study included 16 knees of 16 patients with suspected cartilage lesions. The MR imaging in transverse and sagittal planes included (a) FS 3D FLASH (TR/TE: 45 ms/11 ms, scan time 8 min, flip angle 50°), and (b) WE 3D FLASH (TR/TE: 28 ms/11 ms, scan time 4 min 58 s, flip angle 40°). For each sequence signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were quantified. The detected cartilage lesions were evaluated using a semi-quantitative four-scale scoring system (grades 0–III). The data were compared between the sequences using the paired Student's t-test. No statistically significant differences between the sequences were found for SNR, CNR, and cartilage defect grading (p=0.14–0.8). The WE 3D FLASH MR imaging seems to be promising for fast imaging of articular cartilage lesions of the knee. Electronic Publication     

MR imaging of intracranial hemorrhage in neonates and infants at 2.35 Tesla

Summary The variations of the relative signal intensity and the time dependent changing contrast of intracranial hemorrhages on high-field spin-echo magnetic resonance images (MRI) were studied in 28 pediatric patients. For T1-weighted images, a repetition time (TR) of 500 ms and an echo time (TE) of 30 or 23 ms was used. The corresponding times for T2-weighted images were TR 3000 ms and TE 120 ms. Intracranial hematomas, less than 3 days old, were iso- to mildly hypointense on short TR/TE scans and markedly hypointense on long TR/TE scans (acute stage). In the following four days the signal of the hematomas became hyperintense on short TR/TE scans, beginning in the periphery and proceeding towards the center. On long TR/TE scans the signal remained markedly hypointense (early subacute stage). 7–14 days old hematomas were of high signal intensity on short TR/TE scans. On long TR/TE scans they appeared hypointense in the center and hyperintense in the periphery (late subacute stage). By the end of the second week the hematomas were of high signal intensity on all pulse sequences (chronic stage). Chronic hematomas were surrounded by a parenchymal rim of hypointensity on long TR/TE scans. 28 neonates and infants (with 11 follow-up examinations) of 31.5–70.6 weeks postconceptional age (PCA), with an intracranial hemorrhage were examined. The etiologies of the hemorrhages were: asphyxia (17 cases), brain infarct (2), thrombocytopenia (1), clotting disorder (1) and unknown origin (7). The aim of this study was to describe the appearance of intracranial hemorrhages inneonates and infants with MRI at2.35 Tesla using spine-cho sequences.     

3D 23Na MRI of human skeletal muscle at 7 Tesla: initial experience

Objective

To evaluate healthy skeletal muscle pre- and post-exercise via 7 T ²³Na MRI and muscle proton T₂ mapping, and to evaluate diabetic muscle pre- and post-exercise via 7 T ²³Na MRI.

Methods

The calves of seven healthy subjects underwent imaging pre- and post-exercise via 7 T ²³Na MRI (3D fast low angle shot, TR/TE?=?80 ms/0.160 ms, 4 mm?×?4 mm?×?4 mm) and 1 week later by ¹H MRI (multiple spin-echo sequence, TR/TE?=?3,000 ms/15–90 ms). Four type 2 diabetics also participated in the ²³Na MRI protocol. Pre- and post-exercise sodium signal intensity (SI) and proton T₂ relaxation values were measured/calculated for soleus (S), gastrocnemius (G), and a control, tibialis anterior (TA). Two-tailed t tests were performed.

Results

In S/G in healthy subjects post-exercise, sodium SI increased 8–13% (p?<?0.03), then decreased (t _1/2?=?22 min), and ¹H T₂ values increased 12–17% (p?<?0.03), then decreased (t _1/2?=?12–15 min). In TA, no significant changes in sodium SI or ¹H T₂ values were seen (?2.4 to 1%, p?>?0.17). In S/G in diabetics, sodium SI increased 10–11% (p?<?0.04), then decreased (t _1/2?=?27–37 min) without significant change in the TA SI (?3.6%, p?=?0.066).

Conclusion

It is feasible to evaluate skeletal muscle via 3D ²³Na MRI at 7 T. Post-exercise muscle ¹H T₂ values return to baseline more rapidly than sodium SI. Diabetics may demonstrate delayed muscle sodium SI recovery compared with healthy subjects.     

Optimization of the techniques for studying the upper abdomen with magnetic resonance. II. Changes in the intrinsic contrast

Magnetic Resonance imaging of the upper abdomen was performed on more than 300 patients. The aim of the study was to determine the influence of spin-echo parameters on intrinsic image contrast. Different TR (ranging 260 to 2000 ms) and TE (ranging 20 to 120 ms) values were employed in two patients with a hepatic metastases and in a healthy volunteer with a hepatic cyst. The highest liver-to-lesion contrast was observed when the shortest TR and TE values (260 and 20 ms, respectively) were used, while the lesions appeared isointense with the surrounding parenchyma with TR 800 ms. In T2-weighted images TR 2000 ms allowed the complete recovery of longitudinal magnetization, giving a contrast relative only to the T2 of the lesion.     

Temporal and regional changes during focal ischemia in rat brain studied by proton spectroscopic imaging and quantitative diffusion NMR imaging

The early development of focal ischemia after permanent occlusion of the right middle cerebral artery (MCA) was studied in six rats using interleaved measurements by diffusion-weighted NMR imaging (DWI) of water and two variants of proton spectroscopic imaging (SI), multiecho SI (TE: 136, 272, 408 ms) and short TE SI (TE: 20 ms). Measurements on a 4.7-T NMR imaging system were performed between the control phase and approximately 6 h postocclusion. In the center of the ischemic lesion of all rats, the apparent diffusion coefficient (ADC) decreased rapidly to 84.4 ± 4.2% (mean ± SD) of the control values approximately 2 min postocclusion. Approximately 6 h postocclusion, the ADC was reduced to 67.1 ± 5.9%. In contrast, large differences between the animals were observed for the temporal increase of lactate (Lac) in the ipsilateral hemisphere. The maximum Lac signal was reached in four rats after 0.5-1.5 h, and in two rats was not reached even after 6 h postocclusion. Six h postocclusion, SI spectra measured at a TE of 136 ms revealed a decrease in the CH³ signal of N-acetylaspartate (NAA) to 67 ± 13% of the control values. Differences were observed between the spatial regions of decreased NAA and increased Lac. In the lesions, a T2 relaxation time of Lac of 292 ± 40 ms, considering a J-cou-pling constant of 6.9 Hz, was measured. Furthermore, a prolongation of the T₂ of the CH₃ signal of creatine/phosphocre-atine (Cr/PCr) was observed in the lesion, from 163 ± 22 ms during control to 211 ± 41 ms approximately 6 h postocclusion. The experiments proved that DWI and proton SI are valuable tools to provide complementary information on processes associated with brain infarcts.     

MRI of the plantar structures of the foot after falanga torture

Falanga is an ancient form of punishment or torture but is still commonly reported by our refugees. The late result of caning the heel and ball of the foot is a chronic painful condition with few clinical signs. The aim of the present study was to assess, by MRI, possible morphologic characteristics of the heel and ball of the foot, related to falanga and pain in correlation to clinical findings. Magnetic resonance imaging of the foot was obtained in 12 victims exposed to falanga torture and 9 healthy volunteers. Sagittal T1-weighted spin-echo images (TR 616–840 ms, TE 20 ms), T2-weighted spin-echo images (TR 1900 ms, TE 90 ms), and short tau inversion recovery (STIR) images (TR 1200 ms, TE 15 ms, TI 100 ms) were performed. The central portion of the plantar aponeurosis was generally significantly thicker in victims exposed to falanga torture as compared with that of controls (P < 0.05). In all except one of the victims, MRI demonstrated two layers of the thickened plantar aponeurosis: a deeper portion with normal homogeneous low signal intensity (SI) appearance, and a superficial layer with characteristic areas of mixed SI on both T1- and T2-weighted images. There were no signs of chronic muscular compartment syndromes, and the thickness of the plantar pad did not differ between the two groups. Magnetic resonance imaging may demonstrate morphologic characteristics of the plantar aponeurosis which may confirm falanga torture. Further imaging with more specific sequences is warranted to demonstrate the supposed injuries in the compartmental fat tissue chambers and the vascularity of the ball pad of the foot. Received: 25 November 1999; Revised: 8 February 2000; Accepted: 6 April 2000     

Clinical use of rapid T2 weighted partial saturation sequences in MR imaging

Rapid T2 dependent field echo [partial saturation (PS)] sequences were used in 38 patients with brain tumors, intracerebral hematomas, and cerebral infarction as well as other neurological and abdominal disease. Reduction in the radiofrequency excitation angle (alpha) from 90 to 30 degrees produced an increase in lesion contrast as did change of echo time (TE) from 33 to 59 or 120 ms using repetition time (TR) values in the range of 120-500 ms. The PS sequence showing most lesion contrast was compared with conventional spin echo (SE 1,500/80 and SE 1,500/120) and inversion recovery (IR 1,500/500/44 and IR 1,500/100/44) sequences. Although PS sequences with TE = 39 ms were usually inferior to conventional SE sequences, those with TE = 59 or 120 ms were comparable and in some cases (particularly hematomas) superior. The PS sequences with alpha of approximately 30 degrees, TR of 80-250 ms, and TE of 60-120 ms offer considerable savings in time compared with conventional sequences although more work will be required to explore the limits of this approach and to optimize sequences at different field strengths.     

Real-time cardiac cine imaging with SPIDER: steady-state projection imaging with dynamic echo-train readout.

Steady-state projection imaging with dynamic echo-train readout (SPIDER) is a multiecho radial k-space trajectory TrueFISP sequence developed for real-time cine imaging of the heart. This new pulse sequence combines the superior SNR and blood-to-myocardium contrast of TrueFISP with the increased scan time efficiency of EPI and undersampled projection reconstruction. SPIDER sequence RF repetition time (TR) was minimized by limiting the echo-train to a length of three while acquiring the first and third echoes asymmetrically. A temporal resolution of 45 ms was achieved with TR/TE1/TE2/TE3 of 3.24/0.6/1.6/2.6 ms and a factor of 2 view sharing scheme. Phantom experiments showed little difference between the weighting of the signals acquired at each of the echo times but did show considerable off-resonance modulation between them. In vivo experiments demonstrated the feasibility of using the SPIDER sequence for real-time imaging in the cardiac short axis orientation.