PurposeTo use perfusion and magnetic resonance (MR) spectroscopy to compare the diffusion tensor imaging (DTI)‐defined invasive and noninvasive regions. Invasion of normal brain is a cardinal feature of glioblastomas (GBM) and a major cause of treatment failure. DTI can identify invasive regions.Materials and MethodsIn all, 50 GBM patients were imaged preoperatively at 3T with anatomic sequences, DTI, dynamic susceptibility perfusion MR (DSCI), and multivoxel spectroscopy. The DTI and DSCI data were coregistered to the spectroscopy data and regions of interest (ROIs) were made in the invasive (determined by DTI), noninvasive regions, and normal brain. Values of relative cerebral blood volume (rCBV), N‐acetyl aspartate (NAA), myoinositol (mI), total choline (Cho), and glutamate + glutamine (Glx) normalized to creatine (Cr) and Cho/NAA were measured at each ROI.ResultsInvasive regions showed significant increases in rCBV, suggesting angiogenesis (invasive rCBV 1.64 [95% confidence interval, CI: 1.5–1.76] vs. noninvasive 1.14 [1.09–1.18]; P < 0.001), Cho/Cr (invasive 0.42 [0.38–0.46] vs. noninvasive 0.35 [0.31–0.38]; P = 0.02) and Cho/NAA (invasive 0.54 [0.41–0.68] vs. noninvasive 0.37 [0.29–0.45]; P = < 0.03), suggesting proliferation, and Glx/Cr (invasive 1.54 [1.27–1.82] vs. noninvasive 1.3 [1.13–1.47]; P = 0.028), suggesting glutamate release; and a significantly reduced NAA/Cr (invasive 0.95 [0.85–1.05] vs. noninvasive 1.19 [1.06–1.31]; P = 0.008). The mI/Cr was not different between the three ROIs (invasive 1.2 [0.99–1.41] vs. noninvasive 1.3 [1.14–1.46]; P = 0.68). In the noninvasive regions, the values were not different from normal brain.ConclusionCombining DTI to identify the invasive region with perfusion and spectroscopy, we can identify changes in invasive regions not seen in noninvasive regions. J. Magn. Reson. Imaging 2016;43:487–494.

It is possible to identify three invasive phenotypes in GBMs using Diffusion tensor imaging , and these three phenotypes have different progression free survival. A minimal phenotype (20% of patients) predicts a greater delay to progression.

SummaryBackgroundRestricted diffusion is the second most common atypical presentation of PRES. This has a very important implication, as lesions with cytotoxic edema may progress to infarction. Several studies suggested the role of DWI in the prediction of development of infarctions in these cases. Other studies, however, suggested that PRES is reversible even with cytotoxic patterns. Our aim was to evaluate whether every restricted diffusion in PRES is reversible and what factors affect this reversibility.Material/MethodsThirty-six patients with acute neurological symptoms suggestive of PRES were included in our study. Inclusion criteria comprised imaging features of atypical PRES where DWI images and ADC maps show restricted diffusion. Patients were imaged with 0.2-T and 1.5-T machines. FLAIR images were evaluated for the severity of the disease and a FLAIR/DWI score was used. ADC values were selectively recorded from the areas of diffusion restriction. A follow-up MRI study was carried out in all patients after 2 weeks. Patients were classified according to reversibility into: Group 1 (reversible PRES; 32 patients) and Group 2 (irreversible changes; 4 patients). The study was approved by the University’s research ethics committee, which conforms to the declaration of Helsinki.ResultsThe age and blood pressure did not vary significantly between both groups. The total number of regions involved and the FLAIR/DWI score did not vary significantly between both groups. Individual regions did not reveal any tendency for the development of irreversible lesions. Similarly, ADC values did not reveal any significant difference between both groups.ConclusionsPRES is completely reversible in the majority of patients, even with restricted diffusion. None of the variables under study could predict the reversibility of PRES lesions. It seems that this process is individual-dependent.

Background Perianal fistulas are a common inflammatory condition of the anal canal and perianal tissue. The introduction of MRI in the evaluation of suspected perianal inflammation has greatly improved the surgical outcome of these patients as it allowed the direct visualization of anal sphincters, levator ani muscle, and the extent of the disease in relation to these vital structures. Diffusion-weighted imaging (DWI) has been under extensive research to evaluate whether it adds any value in the setting of perianal inflammation. The aim of our study was to evaluate the visibility of perianal inflammation on DWI and evaluate the diffusion characteristics of perianal fistulas and abscesses and how accurately can DWI classify perianal disease. Results Mean age of patients was 37 ± 8.9 years old. The study included 30 fistulas and 15 abscesses. Seven patients had more than 1 fistula or fistula and abscess. Perianal abscesses were well visualized equally on DWI and T2W images and correctly classified by DWI, when compared to post-contrast images. Perianal fistulas without abscesses, on the other hand, had variable visibility scores. Although the visibility of these fistulas on DWI was generally less than T2W and combined DWI and T2W, yet this did not reach a significant level and it was not significantly different between positive and negative inflammatory groups. Combined DWI and T2W evaluation had the highest performance and accurately classified 97.8 % of perianal fistulas and abscesses, and only 1 case was misclassified (2.3%). Conclusion DWI had a good performance in the evaluation of perianal inflammatory disease. However, combined DWI and T2W evaluation had better performance which was not significantly different from combined T2W and post-contrast images.

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