Ajnr silenz pulse seqquence1/5/2024 ![]() With older and taller children, the bSSFP sequence comprised three, 30-cm, superior-to-inferior segment slabs. For smaller children, the bSSFP sequence comprised two, 30-cm, superior-to-inferior segment slabs. The same imaging protocol was used for all patients regardless of age or histologic tumor type.īSSFP (CISS) sequence parameters performed on the 3T Tim Trio scanner included TR/TE = 11.69/5.85 ms, NEX = 1, echo train = 1, matrix = 448 × 269, flip angle = 50°, slice thickness = 0.8 mm, slice spacing = 0 mm, cervicothoracic spine FOV = 15 × 3–5 × 199–220 mm (anterior-to-posterior × right-to-left × superior-to-inferior), thoracolumbar spine FOV = 15 × 3–5 × 199–220 mm (anterior-to-posterior × right-to-left × superior-to-inferior), voxel size = 0.55–0.58 mm 3, with a scan time of approximately 5 minutes 20 seconds. Sequences reviewed included a bSSFP sequence of the cervicothoracic and thoracolumbar spine and a postcontrast sagittal T1 sequence with a similar FOV. Spine imaging was performed immediately following the brain MRI without the administration of an additional dose of contrast. All patients received the same intravenous gadolinium contrast agent, gadoterate meglumine. MRI examinations were performed on either a 1.5T Signa Excite HDx scanner (GE Healthcare, Milwaukee, Wisconsin) with an 8-channel spine coil or a 3T Tim Trio scanner (Siemens, Erlangen, Germany) with a 32-channel spine coil. Exclusion criteria were patients with examinations degraded by technical or motion artifacts precluding a diagnostic assessment, patients with MRI examinations performed immediately following a brain operation to minimize the amount of postoperative hemorrhage and debris in the spinal canal, and patients with prior spinal radiation or resection of a spinal metastasis. Inclusion criteria were patients 18 years of age or younger with a history of an intracranial neoplasm requiring screening for spinal drop metastases and a preradiation MRI that included a bSSFP sequence and a sagittal T1 postcontrast sequence of the entire spine. All patients were referred for a routine clinical MRI for the detection of spinal drop metastases before radiation treatment. All pediatric patients with a diagnosis of a primary intracranial tumor included in this study were identified through a search of our Radiology Information System. This was a retrospective, institutional review board–approved study examining patients undergoing MR imaging of the spine for the surveillance of drop metastases performed between December 2010 and January 2017 at Massachusetts General Hospital. The purpose of this study was to evaluate the diagnostic utility of the bSSFP sequence compared with conventional postcontrast T1WI for detection of drop metastases in pediatric patients with primary intracranial tumors. The screening protocol for the detection of drop metastases at many institutions primarily consists of a postcontrast T1WI sequence through the entire spine. 2 ⇓ ⇓ ⇓ ⇓ ⇓– 8 Most commonly, the bSSFP sequence has been used for the evaluation of vestibular schwannomas, given its superb fluid-to–soft tissue contrast and high spatial resolution. The bSSFP sequence has been previously used, for example, for the evaluation of duplicated spinal nerve roots and a detailed assessment of spinal cord pathology, including diastematomyelia and syringomyelia. The bSSFP sequence is advantageous for spine imaging, given its superior contrast resolution, enabling sharp discrimination of CSF from the spinal cord and adjacent nerve roots, superior spatial resolution, and isotropy allowing triplanar reconstruction. 1Ī balanced steady-state free precession (bSSFP) scan (CISS/FIESTA/3D driven equilibrium radiofrequency reset pulse) is a heavily fluid-weighted isotropic sequence. Identification of drop metastases can change radiation planning from focal radiation of the primary tumor bed to craniospinal radiation and may mandate the intensification of both radiation and chemotherapy for appropriate treatment. The inclusion of spinal imaging is particularly important for those tumors with a propensity for drop metastases. Spinal cord imaging is considered standard of care for the staging and treatment planning of pediatric brain tumors. ABBREVIATION: bSSFP balanced steady-state free precession
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