Volumetric Assessment of Hippocampus and Subcortical Gray Matter Regions in Alzheimer Disease and Amnestic Mild Cognitive Impairment.

BACKGROUND: Quantitative MRI assessment methods have limited utility due to a lack of standardized methods and measures for Alzheimer disease (AD) and amnestic mild cognitive impairment (aMCI). OBJECTIVE: To employ a relatively new and easy-to-use quantitative assessment method to reveal volumetric changes in subcortical gray matter (GM) regions, hippocampus, and global intracranial structures as well as the diagnostic performance and best thresholds of total hippocampal volumetry in individuals with AD and those with aMCI. METHOD: A total of 74 individuals-37 with mild to moderate AD, 19 with aMCI, and 18 with normal cognition (NC)-underwent a 3T MRI. Fully automated segmentation and volumetric measurements were performed. RESULTS: The AD and aMCI groups had smaller volumes of amygdala, nucleus accumbens, and hippocampus compared with the NC group. These same two groups had significantly smaller total white matter volume than the NC group. The AD group had smaller total GM volume compared with the aMCI and NC groups. The thalamus in the AD group showed a subtle atrophy. There were no significant volumetric differences in the caudate nucleus, putamen, or globus pallidus between the groups. CONCLUSION: The amygdala and nucleus accumbens showed atrophy comparable to the hippocampal atrophy in both the AD and aMCI groups, which may contribute to cognitive impairment. Hippocampal volumetry is a reliable tool for differentiating between AD and NC groups but has substantially less power in differentiating between AD and aMCI groups. The loss of total GM volume differentiates AD from aMCI and NC.

Dynamic contrast-enhanced magnetic resonance imaging for evaluating early response to radiosurgery in patients with vestibular schwannoma.

PURPOSE: This study aimed to use dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to evaluate early treatment response in vestibular schwannoma (VS) patients after radiosurgery. METHODS: Twenty-four VS patients who underwent gamma knife radiosurgery were prospectively followed up for at least four years. DCE-MRI sequences, in addition to standard MRI protocol, were obtained prior to radiosurgery, at 3 and 6 months. Conventionally, treatment responses based on tumor volume changes were classified as regression or stable (RS), transient tumor enlargement (TTE), and continuous tumor enlargement (CTE). DCE-MRI parameters, such as Ktrans, Kep and Ve, were compared according to follow-up periods and between groups. The diagnostic performance was tested using receiver operating characteristic (ROC) curves. RESULTS: Changes in tumor volume were as follows at the last 48 months of follow-up: RS in 11 patients (45.8%), TTE in 10 patients (41.7%), and CTE in three patients (12.5%). The median time required to distinguish TTE from CTE using conventional MRI was 12 months (range 9-18). The Ktrans and Ve were significantly decreased in patients with RS and TTE at 3 and 6 months, but did not differ significantly in patients with CTE. There were no significant differences in Ktrans and Ve between patients with RS and TTE at 3 and 6 months. Both Ktrans and Ve demonstrated high diagnostic performance in evaluating early treatment response to radiosurgery in patients with VS. CONCLUSION: DCE-MRI may aid in the monitoring and early prediction of treatment response in patients with VS following radiosurgery.

Prediction of IDH Mutation Status in High-grade Gliomas Using DWI and High T1-weight DSC-MRI.

RATIONALE AND OBJECTIVES: We aimed to evaluate the diagnostic performance of diffusion-weighted imaging (DWI) and dynamic susceptibility contrast-enhanced (DSC) magnetic resonance imaging (MRI) parameters in the noninvasive prediction of the isocitrate dehydrogenase (IDH) mutation status in high-grade gliomas (HGGs). MATERIALS AND METHODS: A total of 58 patients with histopathologically proved HGGs were included in this retrospective study. All patients underwent multiparametric MRI on 3-T, including DSC-MRI and DWI before surgery. The mean apparent diffusion coefficient (ADC), relative maximum cerebral blood volume (rCBV), and percentage signal recovery (PSR) of the tumor core were measured and compared depending on the IDH mutation status and tumor grade. The Mann-Whitney U test was used to detect statistically significant differences in parameters between IDH-mutant-type (IDH-m-type) and IDH-wild-type (IDH-w-type) HGGs. Receiver operating characteristic curve (ROC) analysis was performed to evaluate the diagnostic performance. RESULTS: The rCBV was significantly higher, and the PSR value was significantly lower in IDH-w-type tumors than in the IDH-m group (p = 0.002 and <0.001, respectively).The ADC value in IDH-w-type tumors was significantly lower compared with the one in IDH-m types (p = 0.023), but remarkable overlaps were found between the groups. The PSR showed the best diagnostic performance with an AUC of 0.938 and with an accuracy rate of 0.87 at the optimal cutoff value of 86.85. The combination of the PSR and the rCBV for the identification of the IDH mutation status increased the discrimination ability at the AUC level of 0.955. In terms of each tumor grade, the PSR and rCBV showed significant differences between the IDH-m and IDH-w groups (p ≤0.001). CONCLUSION: The rCBV and PSR from DSC-MRI may be feasible noninvasive imaging parameters for predicting the IDH mutation status in HGGs. The standardization of the imaging protocol is indispensable to the utility of DSC perfusion MRI in wider clinical usage.

Added Value of CT Pelvic Bone Unfolding Software to Radiologist Performance in Detecting Osteoblastic Pelvic Bone Lesions in Patients With Prostate Cancer.

PURPOSE: To evaluate the contribution of CT Bone Unfolding software to the diagnostic accuracy and efficiency for the detection of osteoblastic pelvic bone lesions in patients with prostate cancer. METHODS: A total of 102 consecutive (January 2016-September 2019) patients who underwent abdominopelvic CT with prostate cancer were retrospectively evaluated for osteoblastic pelvic bone lesions, using commercially available the post-processing-pelvic bone flattening-image software package "CT Bone Unfolding." Two radiologists with 3 and 15 years of experience in abdominal radiology evaluated CT image data sets independently in 2 separate reading sessions. At the first session, only MPR images and at the second session MPR images and additionally unfolded reconstructions were assessed. Reading time for each patient was noted. A radiologist with 25 years of experience, established the standard of reference. RESULTS: In the evaluations performed with the MPR-Unfold method, the diagnostic accuracy were found to be 2.067 times higher compared to the MPRs method (P < 0.001). The location of the lesions or the reader variabilities did not show any influence on accuracy (P > 0.05) For all readers the reading time for MPR was significantly longer than for MPR-Unfold (P < 0.05). For both methods substantial to almost-perfect inter-reader agreement was found (0.686-0.936). CONCLUSIONS: The use of unfolded pelvic bone reconstructions increases diagnostic accuracy while decreasing the reading times in the evaluation of pelvic bone lesions. Therefore, our findings suggest that utilizing unfolded reconstructions in addition to MPR images may be preferable in patients with prostate cancer for the screening of osteoblastic pelvic bone lesions.

Validation of combined use of DWI and percentage signal recovery-optimized protocol of DSC-MRI in differentiation of high-grade glioma, metastasis, and lymphoma.

PURPOSE: With conventional MRI, it is often difficult to effectively differentiate between contrast-enhancing brain tumors, including primary central nervous system lymphoma (PCNSL), high-grade glioma (HGG), and metastasis. This study aimed to assess the discrimination ability of the parameters obtained from DWI and the percentage signal recovery- (PSR-) optimized protocol of DSC-MRI between these three tumor types at an initial step. METHODS: DSC-MRI using a PSR-optimized protocol (TR/TE = 1500/30 ms, flip angle = 90°, no preload) and DWI of 99 solitary enhancing tumors (60 HGGs, 24 metastases, 15 PCNSLs) were retrospectively assessed before treatment. rCBV, PSR, ADC in the tumor core and rCBV, and ADC in peritumoral edema were measured. The differences were evaluated using one-way ANOVA, and the diagnostic performance was evaluated using ROC curve analysis. RESULTS: PSR in the tumor core showed the best discriminating performance in differentiating these three tumor types with AUC values of 0.979 for PCNSL vs. others and 0.947 for HGG vs. metastasis. The ADC was only helpful in the tumor core and distinguishing PCNSLs from others (AUC = 0.897). CONCLUSION: Different from CBV-optimized protocols (preload, intermediate FA), PSR derived from the PSR-optimized protocol seems to be the most important parameter in the differentiation of HGGs, metastases, and PCNSLs at initial diagnosis. This property makes PSR remarkable and carries the need for comprehensive DSC-MRI protocols, which provides PSR sensitivity and CBV accuracy together, such as the preload use of the PSR-optimized protocol before the CBV-optimized protocol.

Evaluation of a two-image technique consisting of an axial and a coronal image generated by using the rib-flattening application: effect on reading time and diagnostic validity

Background/aim: When reading a chest CT, a radiologist needs to evaluate each rib one by one due to complex curvy shape, which makes reporting a tiresome and time-consuming task. A new curved planar reformat application that flattens ribs on a single plane may find a place in the radiology reporting room. This study aimed to evaluate the effect of a two-image set created by using the rib-flattening application on the performance of a radiologist in detecting sclerotic rib lesions in cancer patients. Materials and methods: The local Institutional Review Board approved this retrospective study. Two radiologists with different experience levels reviewed chest CT examinations of 106 patients (76 men, 30 women). We divided the patients into group A (n = 54), reviewed by a standard method, and group B (n = 52), reviewed by a standard method and the two-image set created on the rib- flattening application. Reading times, validity indices, and agreement levels with reference data were evaluated for both readers. Results: The median reading time of the junior examiner significantly decreased with the rib-flattening method (160.5 s vs. 70.0 s; P < 0.001). Diagnostic indices of the senior reader were improved significantly at per patient level (group A, AUC: 0.867; group B, AUC: 0.982; P = 0.046). The new method showed better agreement levels (kappa: 0.69 to 0.96) than the general method (kappa: 0.53 to 0.91). Conclusion: Based on improved agreement levels, reading times, and diagnostic validity indices we conclude that a two-image set consisting of an axial and a coronal flattened-rib image may be used in conjunction with an ordinary exam.