Differentiating post radiation necrosis from progression of glioma and pseudoprogression poses a diagnostic conundrum for many clinicians. As radiation therapy and temozolomide chemotherapy have become the mainstay of treatment for higher-grade gliomas, radiation necrosis and post treatment changes such as pseudoprogression have become a more relevant clinical problem for neurosurgeons and neurooncologists. Due to their radiological similarity to tumor progression, accurate recognition of these findings remains paramount given their vastly different treatment regimens and prognoses. However, no consensus has been reached on the optimal technique to discriminate between these two lesions. In order to clarify the types of imaging modalities for recurrent enhancing lesions, we conducted a systematic review of case reports, case series, and prospective studies to increase our current understanding of the imaging options for these common lesions and their efficacy. In particular, we were interested in distinguishing radiation necrosis from true tumor progression. A PubMed search was performed to include all relevant studies where the imaging was used to differentiate between radiation necrosis and recurrent gliomas with post-radiation enhancing lesions. After screening for certain parameters in our study, seventeen articles with 435 patients were included in our analysis including 10 retrospective and 7 prospective studies. The average time from the end of radiation therapy to the onset of a recurrent enhancing lesion was 13.2 months. The most sensitive and specific imaging modality was SPECT with a sensitivity of 87.6 % and specificity of 97.8 %. Based on our review, we conclude that certain imaging modalities may be preferred over other less sensitive/specific techniques. Overall, tests such as SPECT may be preferable in differentiating TP (tumor progression) from RN (radiation necrosis) due to its high specificity, while nonspecific imaging such as conventional MRI is not ideal.

PURPOSE To develop a method for derivation of the cranial-spinal compliance distribution, assess its reliability, and apply to obese female patients with a diagnosis of Idiopathic Intracranial Hypertension (IIH). MATERIALS AND METHODS Phase contrast based measurements of blood and CSF flows to, from, and between the cranial and spinal canal compartments were used with lumped-parameter modeling to estimate systolic volume and pressure changes from which cranial and spinal compliance indices are obtained. The proposed MRI indices are analogous to pressure volume indices (PVI) currently being measured invasively with infusion based techniques. The consistency of the proposed method was assessed using MRI data from 7 aged healthy subjects. Measurement reproducibility was assessed using 5 repeated MR scans from one subject. The method was then applied to compare spinal canal compliance contribution in 7 IIH patients and 6 matched healthy controls. RESULTS In the healthy subjects, as expected, spinal canal contribution was consistently larger than the cranial contribution (average value of 69%). Measurement variability was 8%. In IIH, the spinal canal contribution is significantly smaller than normal controls (60 vs. 78%, P<0.03). CONCLUSION MRI based method for derivation of compliance indices analogous to PVI has been implemented and applied to healthy subjects. The application of the method to obese IIH patients points to the potential role of the spinal canal compartment in IIH.

BACKGROUND AND PURPOSE: Impaired CSF homeostasis and altered venous hemodynamics are proposed mechanisms for elevated pressure in IIH. However, the lack of ventricular expansion steered the focus away from CSF homeostasis in IIH. This study aims to measure intracranial CSF volumes and cerebral venous drainage with MR imaging to determine whether increased CSF volume from impaired CSF homeostasis and venous hemodynamics occur in obesity-related IIH.

Visual loss owing to optic neuropathy or chiasmopathy may be the presenting sign of SLE or the event that leads to this diagnosis. Gadolinium-enhanced MRI is useful for identifying anterior visual pathway lesions in these patients. Corticosteroids are effective in the treatment of this condition; however, relapses requiring further treatment are common.