Effect of field strength on MR images: comparison of the same subject at 0.5, 1.0, and 1.5 T.

To assess the effect of field strength on magnetic resonance (MR) images, the same healthy subject was imaged at three field strengths: 0.5, 1.0, and 1.5 T. Imaging was performed with three similarly equipped MR imagers of the same generation and from the same manufacturer. The same imaging sequences were used with identical parameters and without repetition time correction for field strength. Imaging was performed in four anatomic locations: the brain, lumbar spine, knee, and abdomen. Quantitative image analysis involved calculation of signal-to-noise ratio, contrast-to-noise ratio, and relative contrast; qualitative image analysis was performed by four readers blinded to field strength. The results of all of the examinations were considered to be of diagnostic value. In general, signal-to-noise ratio and contrast-to-noise ratio were lowest at 0.5 T and highest at 1.5 T; relative contrast was not related to field strength. At qualitative analysis, images obtained at 1.0 and 1.5 T were superior to images obtained at 0.5 T; qualitative differences were less important in locations where there is motion or high magnetic susceptibility differences between tissues (e.g., the spine and abdomen). However, excellent image quality was obtained with all three field strengths.

[Abdominal and pelvic segmented T1-weighted echo-planar imaging and MRI. Comparison with T1-TSE and T2-UTSE sequences]. / Echo-planar segmentaire pondéré T1 en IRM abdominale et pelvienne. Comparaison avec les séquences T1 TSE et T2 UTSE.

PURPOSE: To assess, quantitatively and qualitatively, the diagnostic value of a segmented EPI T1W sequence compared to T1W and T2W TSE sequences. MATERIAL AND METHODS: A prospective analysis of abdominal and pelvic MRI examinations of 70 patients (44 women, 26 men, mean age of 61 years), was performed on a 0.5 T supraconductive magnet with 15 mT/m gradients. The sequences were randomized and compared in a blinded fashion by 3 independent reviewers: TSE T1W (TR/TE = 500/12 ms, NSA = 6, turbo factor 5, 3:49 min), EPI T1W (TR/TE = 500/30 ms, NSA = 6, EPI factor = 7, 2:13 min) and UTSE T2W (TR/TE = 1600-2500/100, NSA = 6, turbo factor = 31, 2:20 min). RESULTS: Quantitatively, no significant difference was found between T1W sequences for signal to noise ratio. The EPI T1W sequence had lower signal but stronger enhancement after gadolinium injection. Qualitatively, EPI T1W had significantly less flow artefacts (p < 0.001, wilcoxon test), and more chemical shift artifact (p < 0.01). For lesion detection, differences were not statistically significant between T1W sequences or between paired T1W and T2W sequences (sensitivity and specificity 84 and 86% for TSE T1W 76 and 86% for EPI T1W, 78 and 79% for UTSE T2W, 90 and 65% for TSE T1W-UTSE T2W, 88 and 65% for EPI T1W-UTSE T2W). Kappa concordance test (0.686) and Mac Nemar symmetry test (3.55) were high between T1W sequences. CONCLUSION: The segmented EPI T1W sequence used had equivalent results compared to the TSE T1W sequence, it allows a 40% reduction in acquisition time and this without difference in the diagnostic performances of the reviewers.

Unselected brain 0.5-T MR imaging: comparison of lesion detection and characterization with three T2-weighted sequences.

PURPOSE: To compare the diagnostic values of three T2-weighted sequences in unselected brain 0.5-T magnetic resonance (MR) imaging examinations. MATERIALS AND METHODS: MR imaging was performed in 102 patients because of neurologic symptoms or the follow up "previously known disease." The protocol comprised three T2-weighted sequences: turbo spin-echo (SE), turbo fluid-attenuated inversion-recovery (FLAIR), and gradient and SE (GRASE) sequences. In a prospective, blinded analysis, sequences were compared quantitatively and qualitative by three independent readers for lesion detection and characterization. RESULTS: Twenty-four patients had normal findings, and 78 had abnormal findings, with 121 final diagnoses. Quantitatively, the "white" cerebrospinal fluid (CSF) sequences, turbo SE and GRASE, had higher contrast-to-noise ratios (CNRs) than the "black" CSF sequence, FLAIR, with respect to the signal intensity of white manner, but lower CNRs than FLAIR with respect to the signal intensity of CSF. Qualitatively, for lesion detection, sensitivity and accuracy were significantly higher for FLAIR than for turbo SE or GRASE (P < .05); there was no statistically significant difference between turbo SE or GRASE. FOR lesion characterization, FLAIR was significantly superior to GRASE and turbo SE for white matter disease (P < .05), superior to only turbo SE (P < .05) for vascular disease, and not superior to GRASE or turbo SE for tumors. CONCLUSIONS: The black CSF T2-weighted turbo FLAIR sequence is a useful adjunct to the usual white CSF T2-weighted sequences in unselected brain 0.5-T MR imaging.

Penile fracture: MRI demonstration of a urethral tear associated with a rupture of the corpus cavernosum.

We report a case of traumatic urethral tear associated with a rupture of the corpus cavernosum, demonstrated on MRI. We discuss the potential role of a non-invasive preoperative assessment by MRI.

[Left ovarian vein syndrome]. / Syndrome de la veine ovarienne gauche.

Ovarian vein syndrome is classically described on the right side. Patients present with lumbar pain or renal colics due to a compression of the ureter between the external iliac artery and a dilated ovarian vein. We report an unusual case of left ovarian vein syndrome between a dilated ovarian vein and the psoas muscle, with a similar clinical presentation.

[Magnetic resonance imaging of the pelvis]. / Imagerie par résonance magnétique du pelvis.

Magnetic resonance imaging (MRI) is particularly well suited to pelvic explorations. Normal uterine zonal anatomy and its variations within the menstrual cycle are well codified. MRI is the best preoperative imaging modality for the localization of fibroids. MRI allows a good approach to tissue characterization in benign ovarian tumors and a precise loco-regional assessment in malignant tumors. It could eventually replace the surgical second look after therapy. In prostate cancer, MRI is the most accurate imaging modality to assess capsular invasion.

[Bladder adenomyomatosis. Apropos of a case of segmental involvement. Correlation ultrasonography-MRI]. / L'adénomyomatose vésiculaire. A propos d'un cas d'atteinte segmentaire. Corrélation échographie-IRM.

Adenomyomatosis of the gall bladder is a classical but seldom recognized cause of gallbladder wall thickening. The authors review the imaging features of this disease and emphasize the value of ultrasound and MRI. Although considered a benign disease, some recently described cases of neoplastic transformation may warrant surgery.

[Selective salpingography and tubal interventional radiography]. / Salpinographie sélective et radiologie interventionnelle tubaire.

The study involved 70 patients considered to be sterile and in whom hysterosalpingography showed no tubal passage. Selective catheterisation enabled opacification under pressure in more than 80 p. cent of cases, with perfect visualisation of the entire tubes and significant peritoneal passage. In the presence of obstructive stenosis, disobstruction-reacanalisation using a soft probe was attempted with success in more than one case out of two. Future perspectives of selective salpingography appear to be very large. This technique seems to have a large number of indications apart from transport problems: recanalisation, sterilisation, and tubal antibiotic sensitivity studies.

Enoxaparine low molecular weight heparin: its use in the prevention of deep venous thrombosis following total hip replacement.

UNLABELLED: The effect of Enoxaparin in the prevention of thromboembolism after total hip prosthesis has been controlled by phlebography. 228 consecutives patients were studied with 4 dose regimens: 60 mg once a day, 40 mg once a day, and 30 and 20 mg twice a day. CONCLUSIONS: a total dose of 40 mg once a day or twice a day gives a rate of postoperative thrombosis of 8%.

[Ectrouria. Apropos of a case]. / L'ectrourie. A propos d'une observation.

Report of a case of sirenomelia (mermaid) anomaly. This male fetus was born from a 30 year-old mother and remained alive for 18 hours. The following anomalies were present: Potter's syndrome, absence of external genitalia and internal genital ducts, presence of two male gonads, renal agenesis, lack of bladder and ureteral ducts, single umbilical artery. Were also found: right radial dysplasia, Fallot tetralogy, T.E. fistula with esophageal atresia, lumbo-sacral spina bifida cystica.