Sagittal T1-weighted Sequences Research Articles

3-T MRI of Rectal Carcinoma: Preoperative Diagnosis, Staging, and Planning of Sphincter-Sparing Surgery

The purpose of this study was to assess the accuracy of 3-T MRI in the preoperative diagnosis, staging, and planning of surgical management of rectal carcinoma. Thirty-eight patients (23 men, 15 women) with clinically suspected rectal carcinoma underwent 3-T MRI. Coronal, axial, and sagittal T2-weighted sequences with and without fat suppression; axial T1-weighted spin-echo sequences; axial T1-weighted gradient-echo sequences with and without fat suppression; oblique 2D MR hydrography; and 3D fat-suppressed dynamic contrast-enhanced MRI were performed. Image quality with these sequences was evaluated by three radiologists experienced in body MRI. The significance of difference in results with the sequences was tested. The manner in which MRI staging and feasibility of sphincter-sparing surgery agreed with operative and pathologic findings was evaluated with kappa statistics. Rectal carcinoma was identified on MRI and confirmed histologically in all 38 patients. MRI findings were correctly predictive of T category in 35 cases (accuracy, 92.1%). In 31 (96.9%) of 32 resectable cases,sphincter-sparing surgical approaches were accurately chosen on the basis of MRI findings. Among the 11 sequences, 3D fat-suppressed dynamic contrast-enhanced MRI best delineated tumor margins. Coronal and axial T2-weighted images also well depicted tumor margins with minimal artifact. T2-weighted images were superior to unenhanced T1-weighted images. MRI of rectal cancer at 3 T is accurate for prediction of T category and the feasibility of sphincter-sparing surgery. The best images were obtained with coronal, sagittal, and axial T2-weighted sequences and 3D fat-suppressed dynamic contrast-enhanced MRI.

The appearances of oesophageal carcinoma demonstrated on high-resolution, T2-weighted MRI, with histopathological correlation

This paper describes the spectrum of imaging features of oesophageal adenocarcinoma seen using high-resolution T2-weighted (T2W) magnetic resonance imaging (MRI). Thirty-nine patients with biopsy-proven oesophageal adenocarcinoma were scanned using an external surface coil. A sagittal T2W sequence was used to localise the tumour and to plan axial images perpendicular to the tumour. Fast spin-echo (FSE) T2W axial sequence parameters were: TR/TE, 3,300-5,000 ms/120-80 ms; field of view (FOV) 225 mm, matrix 176x512(reconstructed) mm to 256x224 mm, giving an in-plane resolution of between 1.28x0.44 mm and 0.88x1.00 mm, with 3-mm slice thickness. Thirty-three patients underwent resection and the MR images were compared with the histological whole-mount sections. There were four T1, 12 T2, and 17 T3 tumours. The T2W high-resolution MRI sequences produced detailed images of the oesophageal wall and surrounding structures. Analysis of the imaging appearances for different tumour T stages enabled the development of imaging criteria for local staging of oesophageal cancer using high-resolution MRI. Our study illustrates the spectrum of appearances of oesophageal cancer on T2W high-resolution MRI, and using the criteria established in this study, demonstrates the potential of this technique as an alternative non-invasive method for local staging for oesophageal cancer.

Normal values of the sagittal diameter of the lumbar spine (vertebral body and dural sac) in children measured by MRI

The definition of normal values is a prerequisite for the reliable evaluation of abnormality in the lumbar spine, such as spinal canal stenosis or dural ectasia in patients with Marfan syndrome. Values for vertebral body diameter (VBD) and dural sac diameter (DSD) for the lumbar spine have been published in adults. In children, normal values have been established using conventional radiography or myelography, but not by MRI. To define normal values for the sagittal diameter of the vertebral body and dural sac, and to calculate a dural sac ratio (DSR) in the lumbosacral spine (L1-S1) in healthy children using MRI. A total of 75 healthy children between 6 years and 17 years of age were examined using a sagittal T2-weighted sequence. Sagittal VBD and DSD were measured and a DSR was calculated. This was a retrospective and cross-sectional study. With increasing age there is a significant increase of VBD, a slight increase of DSD, and a slight decrease of DSR. There is no significant sex difference. DSR in healthy children is higher than in healthy adults. MRI is a reliable method demonstrating the natural shape of the lumbosacral spine and its absolute values. These normal values compare well with those established by conventional radiological techniques. Our data may serve as a reference for defining dural ectasia in children with Marfan syndrome.

Magnetic resonance imaging in patients with gestational trophoblastic disease.

The authors describe the magnetic resonance (MR) imaging characteristics in patients with gestational trophoblastic disease (GTD) before and after therapy and to correlate these findings with human gonadotropin levels and the specific histology of GTD. Thirteen women (mean age, 30.1 years) with elevated human chorionic gonadotropin (HCG) levels and histologically proven GTD underwent MR examinations of the pelvis. Magnetic resonance imaging was performed on a 1.5-tesla unit. Axial and sagittal proton density-weighted and T2-weighted and sagittal T1-weighted sequences were obtained. Four patients underwent follow-up studies after 4 and 8 weeks to monitor the response to therapy. Gestational trophoblastic disease was histologically proven with curettage in 11 patients and with hysterectomy in two cases. Nine patients had a diffusely enlarged uterus with pathologic signal intensities. In four patients, a focal tumor mass was observed. All patients showed loss of the zonal anatomy of the uterus in at least one local area. In 11 patients, no uterus zones could be identified throughout the entire uterus. Pathologic dilated tumor vessels were evident in all patients. In all four cases in which follow-up imaging studies were obtained, uterus size, signal intensities, identification of uterus zones, and uterus vessels returned to normal. Magnetic resonance imaging shows trophoblastic tumor infiltration as diffuse uterus enlargement, focal tumor masses, loss of zonal anatomy of the uterus, and pathologic uterine vasculature; this seems to be the most reliable MR imaging finding in patients with GTD. No correlation was found between MR imaging changes and HCG levels or specific histologic types of GTD.

Sellar Emptiness on Routine Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) has provided a clear view of the sella turcica and the pituitary gland, even on "routine" procedures that invariably include the sagittal T1-weighted sequence. A pituitary gland that does not fully occupy the sella is a common observation, even in normal individuals. Terms such as "empty sella" and "partially empty sella" have become more commonly used, occasionally giving rise to some confusion regarding their clinical significance. In a prospective study of 50 "near-normal" patients, based exclusively on the midsagittal T1-weighted image, we have found a statistically significant increase in sellar emptiness with age, a phenomenon that is more prominent in women. The finding of an empty or partially empty sella on routine MRI of the brain is therefore usually of no clinical significance.

Primary lung cancer staging: prospective comparative study of MR imaging with CT.

Forty-four patients with bronchogenic carcinoma were studied prospectively by both computed tomography (CT) and magnetic resonance (MR) imaging of the thorax during the week preceding thoracotomy. Transaxial MR imaging sequences included T1- and T2-weighted sequences. Coronal and sagittal T1-weighted sequences were added according to tumor location. CT and MR studies were reviewed separately, and the results were compared with surgical and pathologic findings on the basis of TNM classification. No statistically significant differences were found between the two imaging methods for the evaluation of tumor extent or node involvement. T2-weighted sequences did not yield further information on tumor extent or node involvement. Additional imaging planes (coronal or sagittal) appeared useful to study chest wall invasion. Analysis of concordances and discordances did not indicate whether one modality could be substituted for the other, or which diagnostic strategy might be more useful.