Image Quality and Performance Benchmarks in Vehicle and Hospital Mammography.

BACKGROUND: Whether the quality and clinical performance of mammograms obtained in vehicles and those obtained in fixed facilities are equal remains unknown. We compared the characteristics of examinees screened in hospital and vehicle settings. PATIENTS AND METHODS: Data from women who had undergone mammography at Shuang Ho Hospital from January 1, 2013, to December 31, 2016, were obtained from the Women's Breast Screening Database and used for analysis. The records revealed that 43,807 and 11,955 women had undergone mammography in vehicle and hospital settings, respectively. The performance benchmarks, including recall rate, cancer detection rate, and positive predictive value, in the 2 settings were compared. In addition, the image quality was compared by reviewing 110 records from each setting. RESULTS: The hospital mammograms had greater subtotal mean scores (189.2 ± 5.9) compared with the vehicle mammograms (185.5 ± 7.7; P < .0001) in the mediolateral oblique view. Mobile mammography contributed to a lower odds ratio of classification in the Breast Imaging Reporting and Data System categories of 0, 4, and 5. In general, all performance benchmarks, including the cancer detection rate and positive predictive value of mobile and hospital mammography, were satisfactory. However, the recall rate with the hospital mammography service was slightly greater than the acceptable benchmark. CONCLUSION: Mobile mammography services should be continued with improvements in image quality. The reduction in the number of patients with a category of 0 in the classification system in both mammography service settings and the enhancement of data linking to previous mammograms warrants additional attention.

Progressive multifocal leukoencephalopathy in a renal transplant patient.

End-stage renal disease (ESRD) has a major impact on health and affects more than 600,000 people in the USA. The current mainstay treatments include dialysis and kidney transplantation (KT), and patients who have received KT have a higher quality of life and a lower mortality risk than those on chronic dialysis. Therefore, KT is considered the more preferred treatment modality for patients with ESRD. However, even though KT results in a higher long-term survival rate, the use of immunosuppressants is associated with various complications, including opportunistic infections and malignancies, which may lead to a higher risk of death in the first year after transplantation. Progressive multifocal leukoencephalopathy (PML) is a rare complication following KT, with an incidence of 0.027% in KT recipients. We present a case of PML following immunosuppressant therapy in a patient who received KT.

Cerebral Motor Functional Connectivity at the Acute Stage: An Outcome Predictor of Ischemic Stroke.

Sixty-seven patients with first acute ischemic stroke onset between 3 to 7 days and 25 age- and sex- matched controls were analyzed for the performance of a resting-state functional MRI to investigate whether the functional connectivity (FC) of the motor network in acute ischemic stroke is independently associated with functional outcomes. The FC of cortical motor network and default mode network was analyzed. The FC was compared between controls, patients with favorable outcomes (modified Rankin Scale, mRS ≤1), and patients with unfavorable outcomes (mRS ≥2) at 3 months. Of the 67 patients, 23 (34%) exhibited unfavorable outcomes. In multivariate analysis, the FC between ipsilesional primary motor cortex (M1) and contralesional dorsal premotor area (PMd) ≤0.63, were independently associated with unfavorable outcomes (odds ratio = 6.32, P = 0.032), whereas the FC of default mode network was not different between groups. The interhemispheric FC of the motor network is an independent predictor of functional outcomes in patients with acute ischemic stroke.

Too Fast or Too Slow? Time and Neuronal Variability in Bipolar Disorder-A Combined Theoretical and Empirical Investigation.

Time is an essential feature in bipolar disorder (BP). Manic and depressed BP patients perceive the speed of time as either too fast or too slow. The present article combines theoretical and empirical approaches to integrate phenomenological, psychological, and neuroscientific accounts of abnormal time perception in BP. Phenomenology distinguishes between perception of inner time, ie, self-time, and outer time, ie, world-time, that desynchronize or dissociate from each other in BP: inner time speed is abnormally slow (as in depression) or fast (as in mania) and, by taking on the role as default-mode function, impacts and modulates the perception of outer time speed in an opposite way, ie, as too fast in depression and too slow in mania. Complementing, psychological investigation show opposite results in time perception, ie, time estimation and reproduction, in manic and depressed BP. Neuronally, time speed can be indexed by neuronal variability, ie, SD. Our own empirical data show opposite changes in manic and depressed BP (and major depressive disorder [MDD]) with abnormal SD balance, ie, SD ratio, between somatomotor and sensory networks that can be associated with inner and outer time. Taken together, our combined theoretical-empirical approach demonstrates that desynchronization or dissociation between inner and outer time in BP can be traced to opposite neuronal variability patterns in somatomotor and sensory networks. This opens the door for individualized therapeutic "normalization" of neuronal variability pattern in somatomotor and sensory networks by stimulation with TMS and/or tDCS.

Fluid-attenuated inversion recovery vascular hyperintensities in predicting cerebral hyperperfusion after intracranial arterial stenting.

PURPOSE: No reliable imaging sign predicting cerebral hyperperfusion after intracranial arterial stenting (IAS) had been described in the literature. This study evaluated the effect of fluid-attenuated inversion recovery vascular hyperintensities (FVHs), also called hyperintense vessel sign on T2-weighted fluid-attenuated inversion recovery (T2-FLAIR) MR images, in predicting significant increase in cerebral blood flow (CBF) defined by arterial spin labeling (ASL) after IAS. METHODS: We reviewed ASL CBF images and T2-FLAIR MR images before (D0), 1 day after (D1), and 3 days after (D3) IAS of 16 patients. T1-weighted MR images were used as cerebral maps for calculating CBF. The changes in CBF values after IAS were calculated in and compared among stenting and nonstenting vascular territories. An increase more than 50% of CBF was considered as hyperperfusion. The effect of FVHs in predicting hyperperfusion was calculated. RESULTS: The D1 CBF value was significantly higher than the D0 CBF value in stenting vascular, contralateral anterior cerebral artery, contralateral middle cerebral artery, and contralateral posterior cerebral artery (PCA) territories (all P < .05). The D1 and D3 CBF values were significantly higher than the D0 CBF value in overall vascular (P < .001), overall nonstenting vascular (P < .001), and ipsilateral PCA (P < .05) territories. The rate of more than 50% increases in CBF was significantly higher in patients who exhibited asymmetric FVHs than in those who did not exhibit these findings. CONCLUSION: FVHs could be a critical predictor of a significant increase in CBF after IAS.

A Case Report of Transient Cortical Blindness After Angiography.

INTRODUCTION: Transient cortical blindness (TCB) is a rare complication after angiography and is proposed to be related to contrast extravasation. We present the first case of TCB after angiography that was evaluated using serial arterial spin-labeling magnetic resonance perfusion (ASLMRP) and susceptibility-weighted imaging (SWI). CASE REPORT: A 65-year-old woman with dyslipidemia who had been treated for left vertebral artery dissection 3 months previously presented with dizziness and right hemiparesis. Magnetic resonance imaging of the brain revealed suspected dissection of the V4 segment of the left vertebral artery. Cerebral angiography was performed using a total of 46 mL of nonionic contrast material. Approximately 3 hours after the procedure, the patient started complaining of a slight headache and nausea along with bilateral cortical blindness. The 6-hour ASLMRP and SWI of the brain, respectively, revealed hypoperfusion and increased oxygen extraction fraction in the bilateral occipital lobes. The patient gradually regained vision over the next 12 hours, and follow-up ASLMRP and SWI revealed normal perfusion and normal SWI findings, respectively. CONCLUSIONS: Hypoperfusion on ASLMRP and increased oxygen extraction fraction on SWI results derived for a patient presenting with TCB were demonstrated. Thus, we hypothesize that endothelin-related vasoconstriction is a pathophysiologic mechanism for TCB. To the best of our knowledge, this report is the first to describe ASLMRP and SWI findings in TCB after angiography.

In vitro comparison of intracranial stent visibility using various concentrations of gadolinium contrast agent under 1.5†T and 3†T MR angiography.

BACKGROUND AND PURPOSE: MR angiography (MRA) is an increasingly used evaluation method following intracranial stenting. However, the various artifacts created by the stent limit this technique. The purpose of this study was to investigate the effects of various concentrations of gadolinium contrast agent on the visibility and signal characteristics of two stents using the a contrast enhanced MRA technique. MATERIAL AND METHOD: Two intracranial stents (Enterprise and Helistent) were placed in polyvinyl chloride tubes as vascular phantoms. They were filled with six different doses of gadolinium contrast agent (1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 mmol/L dimeglumine gadopentetate, respectively) and imaged using 3 T and 1.5 T MR systems. Relative in-stent signal (RIS) was calculated and artificial luminal narrowing (ALN) was obtained using pixel by pixel analysis. RESULT: The Enterprise stent, performed in both 1.5 T and 3 T MR systems, showed mean RIS values much less than those for the Helistent for all different doses of gadolinium solution. Increased gadolinium concentration resulted in a gradual reduction in RIS values in the Enterprise group. Also, ALN in the Enterprise group showed no or little change with various gadolinium doses. CONCLUSIONS: The Enterprise stent demonstrated good luminal visibility regardless of gadolinium concentration. The relative in-stent signals were more predictable in the Enterprise stent with various doses of gadolinium. Therefore, the Enterprise stent has been shown to provide better in-stent visibility compared with the Helistent using various gadolinium doses.

Arterial Spin Labeling Perfusion Study in the Patients with Subacute Mild Traumatic Brain Injury.

BACKGROUND: This study uses a MRI technique, three-dimension pulse continuous arterial spin labeling (3D-PCASL), to measure the patient's cerebral blood flow (CBF) at the subacute stage of mild traumatic brain injury (MTBI) in order to analyze the relationship between cerebral blood flow and neurocognitive deficits. OBJECTIVE: To provide the relationship between cortical CBF and neuropsychological dysfunction for the subacute MTBI patients. METHODS: After MTBI, perfusion MR imaging technique (3D-PCASL) measures the CBF of MTBI patients (n = 23) within 1 month and that of normal controls (n = 22) to determine the quantity and location of perfusion defect. The correlation between CBF abnormalities and cognitive deficits was elucidated by combining the results of the neuropsychological tests of the patients. RESULT: We observed a substantial reduction in CBF in the bilateral frontal and left occipital cortex as compared with the normal persons. In addition, there were correlation between post concussive symptoms (including dizziness and simulator sickness) and CBF in the hypoperfused areas. The more severe symptom was correlated with higher CBF in bilateral frontal and left occipital lobes. CONCLUSION: First, this study determined that despite no significant abnormality detected on conventional CT and MRI studies, hypoperfusion was observed in MTBI group using 3D-PCASL technique in subacute stage, which suggested that this approach may increase sensitivity to MTBI. Second, the correlation between CBF and the severity of post concussive symptoms suggested that changes in cerebral hemodynamics may play a role in pathophysiology underlies the symptoms.

Spectral Imaging for Intracranial Stents and Stent Lumen.

INTRODUCTION: Application of computed tomography for monitoring intracranial stents is limited because of stent-related artifacts. Our purpose was to evaluate the effect of gemstone spectral imaging on the intracranial stent and stent lumen. MATERIALS AND METHODS: In vitro, we scanned Enterprise stent phantom and a stent-cheese complex using the gemstone spectral imaging protocol. Follow-up gemstone spectral images of 15 consecutive patients with placement of Enterprise from January 2013 to September 2014 were also retrospectively reviewed. We used 70-keV, 140-keV, iodine (water), iodine (calcium), and iodine (hydroxyapatite) images to evaluate their effect on the intracranial stent and stent lumen. Two regions of interest were individually placed in stent lumen and adjacent brain tissue. Contrast-to-noise ratio was measured to determine image quality. The maximal diameter of stent markers was also measured to evaluate stent-related artifact. Two radiologists independently graded the visibility of the lumen at the maker location by using a 4-point scale. The mean of grading score, contrast/noise ratio and maximal diameter of stent markers were compared among all modes. All results were analyzed by SPSS version 20. RESULTS: In vitro, iodine (water) images decreased metallic artifact of stent makers to the greatest degree. The most areas of cheese were observed on iodine (water) images. In vivo, iodine (water) images had the smallest average diameter of stent markers (0.33 ± 0.17mm; P < .05) and showed the highest mean grading score (2.94 ± 0.94; P < .05) and contrast/noise ratio of in-stent lumen (160.03 ±37.79; P < .05) among all the modes. CONCLUSION: Iodine (water) images can help reduce stent-related artifacts of Enterprise and enhance contrast of in-stent lumen. Spectral imaging may be considered a noninvasive modality for following-up patients with in-stent stenosis.

Effect of Age on Working Memory Performance and Cerebral Activation after Mild Traumatic Brain Injury: A Functional MR Imaging Study.

PURPOSE: To evaluate the age effect on working memory (WM) performance and functional activation after mild traumatic brain injury (MTBI). MATERIALS AND METHODS: This study was approved by the local research ethics committee. All participants provided written informed consent. N-back WM cerebral activation was assessed with functional magnetic resonance (MR) imaging in 13 younger (mean age, 26.2 years ± 2.9; range, 21-30 years) and 13 older (mean age, 57.8 years ± 6.6; range, 51-68 years) patients with MTBI and 26 age- and sex-matched control subjects. Two functional MR images were obtained within 1 month after injury and 6 weeks after the initial study. Group comparison and regression analysis were performed among postconcussion symptoms, neuropsychologic tests, and WM activity in both groups. RESULTS: In younger patients, initial hyperactivation was seen in the right precuneus and right inferior parietal gyrus (P = .047 and P = .025, respectively) in two-back greater than one-back conditions compared with younger control subjects, whereas in older patients, hypoactivation was seen in the right precuneus and right inferior frontal gyrus (P = .013 and P =.019, respectively) compared with older control subjects. Increased WM activity was associated with increased postconcussion symptoms in the right precuneus (r = 0.57; P = .026) and right inferior frontal gyrus (r = 0.60; P = .019) and poor WM performance in the right precuneus (r = -0.55; P = .027) in younger patients at initial studies but not in older patients. At follow-up examinations, partial recovery of activation pattern and decreased postconcussion symptoms (P = .04) were observed in younger patients but not in older patients. CONCLUSION: The different manifestations of postconcussion symptoms at functional MR imaging between younger and older patients confirmed the important role of age in the activation, modulation, and allocation of WM processing resources after MTBI. These findings also supported that younger patients have better neural plasticity and clinical recovery than do older patients.

Undersized angioplasty and stenting of symptomatic intracranial tight stenosis with Enterprise: Evaluation of clinical and vascular outcome.

BACKGROUND: Severe intracranial arterial stenosis results in more than 10% incidence of stroke and transient ischemic attack. Using undersized angioplasty with off-label closed-cell Enterprise stent may be a feasible alternative option for treating patients with intracranial atherosclerotic disease who fail dual-antiplatelet medical therapy. The results of the authors' study are presented in this paper. MATERIALS AND METHODS: Between January 2013 and July 2014, 24 symptomatic patients with a total of 30 intracranial arterial stenotic lesions refractory to medical therapy, who underwent undersized angioplasty and Enterprise stenting, were retrospectively reviewed in the authors' institution. The results evaluated include technical success rate, clinical outcome measured as modified Rankin Scale at presentation and follow-up, peri-procedural morbidity within 30 days and 1 year, and follow-up vessel patency. RESULTS: Stent deployment was successfully achieved in all stenotic lesions (30/30). Mean pre-stent and post-stent diameter residual stenosis was 81% and 18%, respectively. The peri-procedural complication rate during 30 days after stenting was 10% per lesion (3/30), including intracranial hemorrhage, in-stent thrombosis and ischemic stroke. No further thromboembolic event or complication occurred in any patient more than 30 days after stenting. Modified Rankin scale ≤ 2 was observed in 64% and 83% of patients at initial presentation and follow-up (mean 15.8 months), respectively. Imaging follow-up was available in 17 of 24 patients (70.8%) and 20 of 30 treated lesions (66.6%) with a mean follow-up period of 15.4 months. Only one asymptomatic in-stent restenosis occurred in 20 available lesions (5.0%). CONCLUSION: This preliminary study suggests that using undersized angioplasty and Enterprise stenting may effectively treat high-degree symptomatic intracranial arterial stenosis with favorable clinical and angiographic outcome.

Endovascular Stenting of an Extracranial-Intracranial Bypass Stenosis: A Technical Note.

The use of an extracranial-intracranial (EC-IC) bypass has been a choice to improve the safety of parent vessel occlusion during the management of aneurysm. However, the prognosis and subsequent patency of bypass graft are variable and have seldom been managed by endovascular treatment. A 38-year-old gentleman presented to our hospital with intermittent headache. Subarachnoid hemorrhage caused by an internal carotid artery aneurysm was disclosed on the subsequent examination. He received an EC-IC bypass later. However, graft stenosis was found during follow-up. To solve the stenosis, an endovascular stent was inserted by us. There is seldom report of endovascular treatment of the graft. Here we share our experience under such circumstances.

Spinal Dural Arteriovenous Fistula: Imaging Features and Its Mimics.

Spinal dural arteriovenous fistula (SDAVF) is the most common spinal vascular malformation, however it is still rare and underdiagnosed. Magnetic resonance imaging findings such as spinal cord edema and dilated and tortuous perimedullary veins play a pivotal role in the confirmation of the diagnosis. However, spinal angiography remains the gold standard in the diagnosis of SDAVF. Classic angiographic findings of SDAVF are early filling of radicular veins, delayed venous return, and an extensive network of dilated perimedullary venous plexus. A series of angiograms of SDAVF at different locations along the spinal column, and mimics of serpentine perimedullary venous plexus on MR images, are demonstrated. Thorough knowledge of SDAVF aids correct diagnosis and prevents irreversible complications.

APOE-ε4 Allele Altered the Rest-Stimulus Interactions in Healthy Middle-Aged Adults.

The apolipoprotein E-ε4 allele is a well-known genetic risk factor for late-onset Alzheimer's disease, which also impacts the cognitive functions and brain network connectivity in healthy middle-aged adults without dementia. Previous studies mainly focused on the effects of apolipoprotein E-ε4 allele on single index using task or resting-state fMRI. However, how these evoked and spontaneous BOLD indices interact with each other remains largely unknown. Therefore, we evaluated the 'rest-stimulus interaction' between working-memory activation and resting-state connectivity in middle-aged apolipoprotein E-ε4 carriers (n=9) and non-carriers (n=8). Four n-back task scans (n = 0, 1, 2, 3) and one resting-state scan were acquired at a 3T clinical MRI scanner. The working-memory beta maps of low-, moderate-, and high-memory loads and resting-state connectivity maps of default mode, executive control, and hippocampal networks were derived and compared between groups. Apolipoprotein E-ε4 carriers presented declined working-memory activation in the high-memory load across whole brain regions and reduced hippocampal connectivity compared with non-carriers. In addition, disrupted rest-stimulus interactions were found in the right anterior insula and bilateral parahippocampal regions for middle-aged adults with apolipoprotein E-ε4 allele. The rest-stimulus interaction improved the detectability of network integrity changes in apolipoprotein E-ε4 carriers, demonstrating the disrupted intrinsic connectivity within the executive-functional regions and the modulated memory-encoding capability within hippocampus-related regions.

Sex Differences in Working Memory after Mild Traumatic Brain Injury: A Functional MR Imaging Study.

PURPOSE: To evaluate sex differences in mild traumatic brain injury (MTBI) with working memory functional magnetic resonance (MR) imaging. MATERIALS AND METHODS: Research ethics committee approval and patient written informed consent were obtained. Working memory brain activation patterns were assessed with functional MR imaging in 30 patients (15 consecutive men and 15 consecutive women) with MTBI and 30 control subjects (15 consecutive men and 15 consecutive women). Two imaging studies were performed in patients: the initial study, which was performed within 1 month after the injury, and a follow-up study, which was performed 6 weeks after the first study. For each participant, digit span and continuous performance testing were performed before functional MR imaging. Clinical data were analyzed by using Kruskal-Wallis, Mann-Whitney U, Wilcoxon signed rank, and Fisher exact tests. Within- and between-group differences of functional MR imaging data were analyzed with one- and two-sample t tests, respectively. RESULTS: Among female participants, the total digit span score was lower in the MTBI group than in the control group (P = .044). In initial working memory functional MR imaging studies, hyperactivation was found in the male MTBI group and hypoactivation was found in the female MTBI group compared with control male and female groups, respectively. At the 6-week follow-up study, the female MTBI group showed persistent hypoactivation, whereas the male MTBI group showed a regression of hyperactivation at visual comparison of activation maps. The male MTBI group was also found to have a higher initial ß value than the male control group (P = .040), and there was no significant difference between the male MTBI group and the male control group (P = .221) at follow-up evaluation, which was comparable to findings on activation maps. In the female MTBI group, average ß values at both initial and follow-up studies were lower compared with those in the female control group but were not statistically significant (P = .663 and P = .191, respectively). CONCLUSION: Female patients with MTBI had lower digit span scores than did female control subjects, and functional MR imaging depicted sex differences in working memory functional activation; hypoactivation with nonrecovery of activation change at follow-up studies may suggest a worse working memory outcome in female patients with MTBI.

May-Thurner syndrome: correlation between digital subtraction and computed tomography venography.

BACKGROUND/PURPOSE: Digital subtraction venography (DSV) and computed tomography venography (CTV) are both recommended for diagnosing May-Thurner syndrome. The literature contains little information on the correlation between these imaging tools. We performed a retrospective case-series study to investigate this correlation. METHODS: From August 2009 to August 2010, 42 patients with May-Thurner syndrome (34 women, 8 men; mean age: 52.8 ± 13.5 years) received DSV followed by CTV. The DSV was used to evaluate the degree of venous reflux, reflux start-up time, and flow time. By CTV, the ratio of cross-sectional area and the ratio of diameter between the narrowest region to that of the caudal part of the left common iliac vein were calculated. The correlation between these variables for DSV versus CTV was calculated using Spearman's rank correlation coefficients. RESULTS: In DSV evaluation of the extent of reflux, 19.0% of cases were classified as Grade 0, 11.9% as Grade I, 28.6% as Grade II, and 40.5% as Grade III. The mean ± standard deviation flow times for these groups were 2.00 ± 0.38 seconds, 1.75 ± 0.29 seconds, 1.67 ± 0.72 seconds, and 1.81 ± 0.68 seconds, the mean time for total patients was 1.76 ± 0.78 seconds. The reflux start-up times for Grades I-III were 2.00 ± 1.00 seconds, 1.80 ± 1.23 seconds, and 1.40 ± 0.49 seconds, and the mean time was 1.6 ± 0.8 seconds. In CTV, the mean area ratio and diameter ratio were 0.78 ± 0.22 (range, 0.22-1.27) and 0.75 ± 0.24 (range, 0.33-1.25). The reflux start-up time showed a positive correlation with the cross-sectional area ratio (r = 0.518; p = 0.002) and diameter ratio (r = 0.413; p = 0.019). CONCLUSION: The cross-sectional area ratio and diameter ratio in CTV correlate with the reflux start-up time in DSV. For May-Thurner syndrome, both CTV and DSV provide essential information for diagnosis and evaluation of the disease. The positive correlation between anatomical and hemodynamic properties corresponds with the underlying pathophysiology.

Susceptibility-weighted MRI in mild traumatic brain injury.

OBJECTIVE: To compare the frequency of microbleeds identified by susceptibility-weighted MRI (SWMRI) in patients with mild traumatic brain injury (mTBI) and normal controls, and correlate these findings with neuropsychological tests. METHODS: Research ethics committee approval and patient written informed consents were obtained. One hundred eleven patients with mTBI without parenchymal hemorrhage on CT and conventional MRI received SWMRI as well as a digit span and continuous performance test. One hundred eleven healthy volunteers without history of traumatic brain injury were enrolled as the control group and received conventional MRI with additional SWMRI study. We analyzed the number and location of microbleeds in both groups. RESULTS: Twenty-six patients with mTBI and 12 control subjects presented microbleeds on SWMRI (p = 0.0197). Sixty microbleeds were found in 26 patients with mTBI and 15 microbleeds in 12 control subjects. The mTBI group showed notably more microbleeds in the cortex/subcortical region (52 microbleeds, 86.7%, vs 3 microbleeds, 20%; p < 0.0001). Conversely, the control group showed more microbleeds in the central brain (9 microbleeds, 60%, vs 3 microbleeds, 5%; p < 0.0001). There was no statistical difference in number of microbleeds in the cerebellum and brainstem (p = 0.2598 and p = 0.4932, respectively). Patients with mTBI who had detected microbleeds had lower digit span scores than the patients with negative SWMRI findings (p = 0.017). CONCLUSION: Presence of mTBI-related microbleeds showed a neuropsychological defect on short-term memory function, indicating that the presence of microbleeds could be a possible severity biomarker for mTBI. Addition of the SWMRI technique to the MRI protocol for patients with mTBI is recommended.