Photon-Counting Detector CT for Kidney Stone Detection in Excretory Phase CT-Comparison Between Virtual Non-contrast and Virtual Non-iodine Reconstructions in a 3D Printed Kidney Phantom.

RATIONALE AND OBJECTIVES: To evaluate and compare the effectiveness of contrast media subtraction and kidney stone detection between a virtual non-iodine reconstruction algorithm (VNI; PureCalcium) and a virtual non-contrast (VNC) algorithm in excretory phase photon-counting detector computed tomography (PCD-CT), using a 3D printed kidney phantom under various tube voltages and radiation doses. MATERIALS AND METHODS: A 3D-printed kidney phantom, holding Calcium Oxalate (CaOx) and uric acid stones within contrast-enhanced calyces, was created. The calyx density mirrored the average density observed in 200 excretory phase patients (916 HU at 110 kV). Imaging was conducted on a clinical dual-source PCD-CT at 120 kV and 140 kV, with radiation doses set at 5, 10, and 15 mGy. VNI and VNC algorithms were applied. Two blinded readers evaluated the image quality, along with the degree of contrast media and kidney stone subtraction, using visual scales. Krippendorff's alpha was calculated to determine inter-reader agreement, and the Chi-squared test was employed for comparing ordinal data. RESULTS: Reader 2 rated overall image quality higher for VNI than VNC (4.90 vs. 4.00; P < .05), while Reader 1 found no significant difference (4.96 vs. 5.00; P > .05). Substantial agreement was observed between readers for contrast media subtraction in both VNC and VNI (Krippendorff's alpha range: 0.628-0.748). Incomplete contrast media subtraction occurred more frequently with VNI for both readers (Reader 1: 29% vs. 15%; P < .05; Reader 2: 24% vs. 20%; P > .05). Uric acid and smaller stones (<5 mm) were more likely to be subtracted than CaOx and larger stones in both VNC and VNI. Overall, a higher rate of stone subtraction was noted with VNI compared to VNC (Reader 1: 22% vs. 16%; Reader 2: 25% vs. 10%; P < .05). Neither radiation dose nor tube voltage significantly influenced stone subtraction (P > .05). CONCLUSION: VNC demonstrated greater accuracy than VNI for contrast media subtraction and kidney stone visibility. Radiation dose and tube voltage had no significant impact. Nonetheless, both algorithms still exhibited frequent incomplete contrast media subtraction and partial kidney stone subtraction.

Imaging Neurovascular Uncoupling in Acute Migraine with Aura with Susceptibility Weighted Imaging.

PURPOSE: Migraine with aura (MwA) in the emergency setting is common and sometimes difficult to distinguish from mimicking conditions. Susceptibility weighted imaging (SWI), a magnet resonance (MR) technique is sensitive to deoxygenated hemoglobin in cerebral veins and depicts these according to their level of oxygenation. Our study aimed at evaluating the frequency of regions of prominent focal veins (PFV) on SWI in the acute phase. METHODS: Between 2011 and 2018 we evaluated symptoms and MR imaging of adult patients with acute MwA attacks (< 5 days after onset of symptoms). Abnormal imaging was visually scored in 12 ROIs on both hemispheres distributed on 3 slices. The score ranged from 0 to 3. RESULTS: In all, 638 patients (436 female) mean age 37.39 years (18-89 ±â€¯14.13) were included. Susceptibility weighted imaging was abnormal in 18.8% of patients. The inferior and posterior medial temporal lobe and the occipital lobe were most often affected. Susceptibility weighted imaging was more likely abnormal when MR was performed within 24 hours with an average around 5 hours after symptom onset. The side of aura symptoms and hemispheric imaging alteration in patients with abnormal SWI was highly significant (p < 0.001). CONCLUSION: In the acute episode of MwA, SWI imaging can show a combination of increased deoxygenation. The results may indicate linking PFV to MwA.

Validation of the focal cerebral arteriopathy severity score (FCASS) in a Swiss cohort: Correlation with infarct volume and outcome.

BACKGROUND: Focal cerebral arteriopathy (FCA), a major cause of childhood arterial ischemic stroke (AIS), can progress and lead to increased infarct size and/or recurrent stroke. Evaluating treatment options depends on the ability to quantify reliably the degree of stenosis in FCA. AIMS: We validated the recently introduced FCA severity score (FCASS) in an independent cohort from the Swiss Neuro-Paediatric Stroke Registry (SNPSR). MATERIALS AND METHODS: We included children with FCA who had MR or CT angiography and a Pediatric Stroke Outcome Measure (PSOM) at 6-months and 2-years post-stroke. A paediatric neuroradiologist applied the FCASS and the modified pediatric Alberta Stroke Program Early Computed Tomography Score (ASPECTS), a measure of infarct volume, to all available imaging. Two senior paediatric stroke neurologists and a neuroradiology fellow independently assigned FCASS scores to test interrater reliability. Pairwise correlations between FCASS, pedASPECTS, and PSOM were examined. RESULTS: Thirty-two children [median (IQR) age = 5.9 (1.8, 9.6), 19 males] were included. The median maximum FCASS score at any time was 9 (IQR 6, 12; range 3, 16). Larger infarct volume scores correlated with both higher maximum FCASS scores and worse post-stroke outcomes, although we found no direct correlation between FCASS and outcomes. Stroke neurologists tended to assign lower FCASS scores than the neuroradiologist, but interrater reliability was predominantly good. CONCLUSIONS: In this independent validation cohort, higher maximum FCASS correlated with greater infarct volume scores that also correlated with worse neurological outcomes. Scoring by non-imaging specialists seems to be valuable, although differences are present.

Prevalence and Evolution of Susceptibility-Weighted Imaging Lesions in Patients With Artificial Heart Valves.

Background In patients with mechanical heart valves, cerebral susceptibility-weighted imaging (SWI) lesions on magnetic resonance imaging, postulated to be caused by degenerative metallic abrasion, are frequently referred to as valve abrasion. It remains unclear whether valve implantation not requiring cardiopulmonary bypass or biological heart valves also shows those lesions. Methods and Results Two blinded readers rated SWI lesions and cerebral amyloid angiopathy probability according to established criteria on brain magnetic resonance imaging pre- and postinterventionally. We assessed the association between valve type/cardiopulmonary bypass use and SWI lesion count on the first postinterventional scan using multivariable logistic regression. On postinterventional magnetic resonance imaging, 57/58 (98%) patients with mechanical heart valves had at least 1 and 46/58 (79%) 3 or more SWI lesions, while 92/97 (95%) patients with biological heart valves had at least 1 and 72/97 (74%) 3 or more SWI lesions. On multivariate analysis, duration of cardiopulmonary bypass during implantation significantly increased the odds of having SWI lesions on the first postinterventional magnetic resonance imaging (ß per 10 minutes 0.498; 95% CI, 0.116-0.880; P=0.011), whereas valve type showed no significant association (P=0.338). Thirty-seven of 155 (23.9%) patients fulfilled the criteria of possible/probable cerebral amyloid angiopathy. Conclusions SWI lesions in patients with artificial heart valves evolve around the time point of valve implantation and the majority of patients had multiple lesions. The missing association with the valve type weakens the hypothesis of degenerative metallic abrasion and highlights cardiopulmonary bypass as the main risk factor for SWI occurrence. SWI lesions associated with cardiac procedures can mimic cerebral amyloid angiopathy. Further research needs to clarify whether those lesions are associated with intracranial hemorrhage after intravenous thrombolysis or anticoagulation.

Assessing Spinal Cerebrospinal Fluid Leaks in Spontaneous Intracranial Hypotension With a Scoring System Based on Brain Magnetic Resonance Imaging Findings.

Importance: Various signs may be observed on brain magnetic resonance imaging (MRI) in patients with spontaneous intracranial hypotension (SIH). However, the lack of a classification system integrating these findings limits decision making in clinical practice. Objective: To develop a probability score based on the most relevant brain MRI findings to assess the likelihood of an underlying spinal cerebrospinal fluid (CSF) leak in patients with SIH. Design, Setting, and Participants: This case-control study in consecutive patients investigated for SIH was conducted at a single hospital department from February 2013 to October 2017. Patients with missing brain MRI data were excluded. Three blinded readers retrospectively reviewed the brain MRI scans of patients with SIH and a spinal CSF leak, patients with orthostatic headache without a CSF leak, and healthy control participants, evaluating 9 quantitative and 7 qualitative signs. A predictive diagnostic score based on multivariable backward logistic regression analysis was then derived. Its performance was validated internally in a prospective cohort of patients who had clinical suspicion for SIH. Main Outcomes and Measures: Likelihood of a spinal CSF leak based on the proposed diagnostic score. Results: A total of 152 participants (101 female [66.4%]; mean [SD] age, 46.1 [14.3] years) were studied. These included 56 with SIH and a spinal CSF leak, 16 with orthostatic headache without a CSF leak, 60 control participants, and 20 patients in the validation cohort. Six imaging findings were included in the final scoring system. Three were weighted as major (2 points each): pachymeningeal enhancement, engorgement of venous sinus, and effacement of the suprasellar cistern of 4.0 mm or less. Three were considered minor (1 point each): subdural fluid collection, effacement of the prepontine cistern of 5.0 mm or less, and mamillopontine distance of 6.5 mm or less. Patients were classified into groups at low, intermediate, or high probability of having a spinal CSF leak, with total scores of 2 points or fewer, 3 to 4 points, and 5 points or more, respectively, on a scale of 9 points. The discriminatory ability of the proposed score could be demonstrated in the validation cohort. Conclusions and Relevance: This 3-tier predictive scoring system is based on the 6 most relevant brain MRI findings and allows assessment of the likelihood (low, intermediate, or high) of a positive spinal imaging result in patients with SIH. It may be useful in identifying patients with SIH who are leak positive and in whom further invasive myelographic examinations are warranted before considering targeted therapy.