AJNR Blog » Perfusion MR

educational presentation: atypical features in pres

MCastillo — Mon, 07 Jun 2010 17:24:37 +0000

Here is another presentation that I hope our readers and visitors will find useful and enjoy. We presented this as an “exhibit” at the past meeting of ASNR. The presentation deals with atypical MRI findings in posterior reversible encephalopathy syndrome.

AJNR’s New Special Collection and Podcast Survey Brain Tumor Imaging

MCastillo — Wed, 21 Apr 2010 14:54:35 +0000

“Brain Tumor Imaging, Volume 1: Pretherapy” is the latest Special Collection from the American Journal of Neuroradiology. Distilling the best of the many articles related to brain tumor imaging that appear in the pages of AJNR posed a daunting task, but Editor-in-Chief Mauricio Castillo knew that Collection Editor Soonmee Cha of the University of California, San Francisco would be successful. “Dr. Cha is a respected investigator, a contributor of high quality and clinically relevant articles to AJNR and other journals, and a member of our Editorial Board,” he explained. Dr. Cha chose to categorize and present this compilation of research in two volumes. “Brain tumors consist of a heterogeneous group of neoplasms numbering more than 120 different histologic types with a wide range of clinical, biologic, and prognostic behavior. Due to this breadth, I organized the articles by specific imaging modality and selected those that best utilized imaging to address disease-specific questions,” she said. The first volume covers essential anatomic and physiologic clinical imaging methods as well as highly innovative and potentially ground-breaking imaging that promises even greater progress in caring for brain tumor patients in the future. Volume 2 will include articles that focus on imaging of brain tumors aftertherapy. In the accompanying podcast, Dr. Cha and AJNR’s Podcast Editor C. Douglas Phillips discuss the collaborative role of the neuroradiologist in the treatment and prognosis of brain tumors and the benefits of advanced diagnostic imaging techniques. This special podcast, along with Dr. Phillips’ summaries of each issue’s most salient articles including the Editor’s Choices and Fellow’s Journal Club selections, are available to download on the AJNR Website and in the iTunes Store. AJNR Special Collections provide a comprehensive source of imaging-related articles on a single topic and are released biannually on an open-access basis. Previous Collections include “Imaging Acute Stroke and its Consequences,” edited by Pamela W. Schaefer and R. Gilberto GonzÃ¡lez, “Acute Stroke Intervention” edited by Colin P. Derdeyn and Avi Mazumdar, “Percutaneous Vertebroplasty,” edited by Mary E. Jensen and Joshua A. Hirsch, and “Radiation Dose in Neuroradiology CT Protocols,” edited by Max Wintermark and Michael H. Lev. All are available through AJNR’s print-on-demand service (Brightdoc), where readers can order a full-color hard copy for just US $50.00, plus shipping.

Aunt Mickey (they look the same until you undress them). Meningioma or something else?

Asim — Fri, 15 Jan 2010 20:03:03 +0000

51 year old lady presented with headache and gait disturbances. An MRI including perfusion imaging was obtained. MRI revealed an extra-axial, dural based mass of the posterior fossa which was isointense to gray matter on T1 weighted sequence and hyperintense to gray matter on T2 weighted sequence. There was no diffusion restriction. On T2 weighted sequence, there was wedge shaped area of perilesional T2 hyperintensity extending transversely and superiorly to involve vermis. With contrast, the lesion showed intense homogenous enhancement. On perfusion study, there was considerable increase in rCBV. Preoperatively it was diagnosed as meningioma and the patient was scheduled for resection.

On surgery, the mass was encapsulated but the capsule was tightly adherent to the cerebellum. On histopathology, the tumor turned out to be a malignant fibrous histiocytoma (MFH) with 40% MIB-1 index.

MFH, the most common soft tissue sarcoma in adults, arises from fibroblasts, myofibroblasts or undifferentiated mesenchymal cells. Most patients are between 50 and 70 years old. Men are affected 2-3 times more commonly than women. Most MFHs arise de novo however, they can occur secondary to prior radiation, trauma, Paget’s disease, chronic osteomyelitis or benign bone tumors. MFH most commonly occurs in lower extremity. Head and neck area is involved up to 10% of cases. In head neck, nasal cavity and paranasal sinuses are most commonly involved. It has variable appearances on CT and MRI. On CT, this is usually large lobulated sift tissue mass which is isodense to muscles with destruction/remodeling of adjacent bone. There may calcification in up to 5-20% of patients. On MRI, they are isointense to muscle on T1 weighted sequence and heterogeneously hyperintense on T2 weighted sequence. This tumor can have both solid and cystic component. Solid portion enhances intensely. Spontaneous hemorrhage is frequently seen and can obscure the primary tumor. The diagnosis is important because it is a malignant tumor and post-resection radiation therapy is required for better tumor control. MFH also has poor prognosis.

Aunt Mickey (they look the same until you undress them). Lhermitte-Duclos or something else?

MCastillo — Wed, 07 Oct 2009 17:09:25 +0000

A young man presented with ataxia. Brain contrast enhanced MRI was done including DWI and perfusion. T2WI showed a mixed intensity lesion in the inferior right cerebellar hemisphere which contained some “dark stripes”. DWI ADC map show restricted diffusion centrally. After contrast the lesion enhanced in a striped fashion and perfusion showed low rCBV (see below). Llermitte-Duclos disease was considered in the differential diagnosis.

Further questioning of patient disclosed that the symptoms had had a sudden onset 7 days earlier. The diagnosis of subacute infarction of the right posterior inferior cerebellar artery territory was considered as the most likely cause of the findings. The patient was followed and repeat MRI three months later demonstrated only malacia and atrophy in the location.

Llermitte-Duclos disease (a.k.a. dysplastic gangliocytoma of the cerebellum) is the CNS hallmark of Cowden syndrome. It is probably a malformative hamartoma of the cerebellum seen nearly exclusively in this syndrome. The typical lesion has a “corduroy” or “tiger striped” appearance, does not enhance after contrast, has restricted diffusion (presumably due to its high cellularity), and normal-to-increased perfusion. MRS shows low NAA, decreased Cho/Cr, elevated lactate and high myoinositol and at times the spectra may be near normal (see below). PET shows increased FDG accumulation. Thus to differentiate it from an infarct with similar appearance perfusion and PET studies are best when in doubt. Additionally, contrast enhancement in Llermitte-Duclos is extremely rare.

Crossed Cerebellar Diaschisis

garg.akash — Mon, 27 Jul 2009 20:42:29 +0000

A 41-year-old female with history of migraine presented to the ED with acute onset of aphasia. In addition to the aphasia, there was numbness and tingling in the right arm and face. Patient demonstrated expressive aphasia and was not able to answer questions posed in the ED. Gadolinium MR perfusion images demonstrated decreased relative cerebral blood flow (top) in the left parietal/occipital lobes and increased time-to-peak (bottom) in the contralateral cerebellar hemisphere. Although crossed cerebellar diaschisis (CCD) is seen mostly on radiotracer studies (hypometabolism on PET studies), it was nicely demonstrated in our patient. CCD occurs more often after supratentorial infarctions but has been reported in the setting of migraine. This phenomenon occurs immediately after brain injury due to the large number of functional connections between cerebrum and cerebellum. In reverse CCD, the brain abnormality is due to injury of the cerebellum. Because of the limited number of slices on perfusion MR studies, particularly when using ASL techniques, it is important to keep in mind that the cerebellum may be involved in several supratentorial abnormalities and needs to be included in the study. I would be interested in finding out if anyone else has seen this type of migraine-associated CCD.

ASL Perfusion in Cortical Dysplasia

MCastillo — Tue, 17 Feb 2009 13:58:58 +0000

Arterial spin labeling perfusion is becoming an important clinical tool. We find it particularly useful in children in whom it is difficult to obtain contrast enhanced MR perfusion due to the smaller size of needles used. Here is a case of a balloon cell type cortical dysplasia in the right temporoparietal region with low cerebral blood flow on the ASL study. I think that our Blogsite is the ideal place to share these cases with the rest of the Neuroradiology community. Similar findings to the ones shown here were reported in the following article found in the publication preview section of www.ajnr.org:

Pollock J, Whitlow C, Tan H, et al. Pulsed Arterial Spin-Labeled MR Imaging Evaluation of Tuberous Sclerosis. AJNR Am J Neuroradiol. 10.3174/ajnr.A1428