Brain Perfusion Territory Imaging: Methods and Clinical Applications of Selective Arterial Spin-labeling MR Imaging
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Transverse source images of time-of-flight MR angiography of brain-feeding arteries show planning of the selective arterial spin-labeling slabs for perfusion territory imaging of left internal carotid artery (ICA), right ICA and vertebrobasilar arteries (VBA).
(Radiology 2008;246:354–364) © RSNA, 2008. All rights reserved. Printed with permission. |
In the past decade, optimization of selective arterial spin-labeling (ASL) MR imaging techniques to image the cerebral perfusion territories has resulted in numerous labeling approaches and an increasing number of clinical applications. As a result, ASL MR imaging is emerging as a noninvasive alternative to reference standard intraarterial digital subtraction angiography (DSA).
In a review article in the February issue of Radiology (RSNA.org/radiology), Peter Jan van Laar, M.D., Jeroen van der Grond, Ph.D., and Jeroen Hendrikse, M.D., Ph.D., from the University Medical Center Utrecht and Leiden University Medical Center in The Netherlands, describe ASL MR imaging methods and demonstrate how ASL MR imaging contributes to the study of cerebral hemodynamic changes in patients with cerebrovascular disease such as acute stroke, large artery steno-occlusive disease and arteriovenous malformation.
The researchers address continuous ASL and pulsed ASL techniques, clinical application in cerebrovascular intervention and the capacity of ASL MR for quantitative analysis of regional cerebral blood flow from each individual feeding artery.
"In the future, this technique may be capable of replacing diagnostic intraarterial DSA in a selected group of patients," the researchers conclude. "Furthermore, selective ASL MR is especially suited for noninvasive follow-up after vascular interventions. … As a noninvasive tool for perfusion territory measurements, we believe selective ASL will contribute to a better understanding of the relation between vasculature, perfusion and brain function."
MR Imaging Features of Vaginal Malignancies
This article meets the criteria for 1.0 AMA PRA Category 1 Credit™. CME is available online only.
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Vaginal metastasis in a 60-year-old patient with a stage IIIC malignant ovarian mixed müllerian tumor who presented with vaginal bleeding, pneumaturia and fecal leakage.
(a) Sagittal T2-weighted MR image shows a 10 x 10 x 8.5 cm mass arising from the posterior vaginal vault and invading the sigmoid colon superiorly (arrow). The mass has heterogeneous high signal intensity and contains multiple loculi.
(b) Axial T2-weighted MR image shows that the mass invades the bladder (black arrow), which contains gas (white arrow) as a result of a fistulous connection.
(RadioGraphics 2008;28:49–63) © RSNA, 2008. All rights reserved. Printed with permission. |
In diagnosing and staging primary vaginal malignancies, MR imaging can provide details not readily assessed at examination under anesthesia and is crucial in demonstrating tumor location, parametrial extension, pelvic sidewall involvement and spread to the bladder or urethra, rectum and lymph nodes. MR imaging can also help depict pelvic anatomy for surgical and radiation therapy planning.
In an article in the January-February issue of RadioGraphics (RSNA.org/radiographics), Jyoti H. Parikh, F.R.C.R., of the Royal Marsden Hospital NHS Foundation Trust in London, and colleagues review primary vaginal malignancies and vaginal metastases and discuss their imaging features with respect to MR imaging.
Specifically, Dr. Parikh and colleagues address:
• MR imaging technique for vaginal malignancies
• Patterns and extent of disease in
primary squamous cell vaginal carcinoma
• MR imaging features of the histologic subtypes of primary nonsquamous vaginal carcinomas, including adenocarcinoma, melanoma, leiomyosarcoma and spindle cell synovial sarcoma
• Disease patterns and MR imaging features of gynecologic and nongynecologic vaginal metastases
"The superb soft-tissue contrast resolution of MR imaging depicts the nature of vaginal malignancies," the authors conclude. "MR imaging allows detailed assessment of the anatomic extent of the disease and also its characteristic appearance, thus assisting in management of the tumor."
Results of a recent reader survey indicate that RadioGraphics is fulfilling its mission more successfully than ever and provide valuable feedback for upcoming issues.
Reader responses have already inspired an increased focus on quality initiatives, CME offerings, informatics and lifelong learning, consideration of options for print versus online reading and continued outreach to the international community.
The latest survey follows much the same format as those conducted in 1991, 1997 and 2002. "We are very pleased with how the survey was conducted," said RadioGraphics Editor William W. Olmsted, M.D. "We have kept more or less the same questions throughout so we can track data longitudinally, though certainly with a few additions—for example, the online version has become more prominent.
"These surveys give us an opportunity to see where we are and give us a chance to make positive changes for the future of the journal," Dr. Olmsted concluded.
An article detailing all the survey results will be published in the March 2008 issue of RSNA News.
