Inferior and Superior Vena Cava Reconstruction.

Obstructions of the superior and inferior vena cava are prevalent etiologies of deep venous obstruction, presenting a spectrum of clinical manifestations ranging from life-threatening conditions to asymptomatic states. The etiological diversity inherent to these central venous obstructions necessitates a subtle approach to their diagnosis and management. This discrepancy in clinical presentations emphasizes the importance of a differentiated diagnostic and therapeutic strategy, tailored to the specific form of vena cava obstruction encountered. This article aims to delineate the various manifestations of vena cava obstruction and encourages specific diagnostic and treatment pathways.

Deep Learning-Based Denoising Enables High-Quality, Fully Diagnostic Neuroradiological Trauma CT at 25% Radiation Dose.

RATIONALE AND OBJECTIVES: Traumatic neuroradiological emergencies necessitate rapid and accurate diagnosis, often relying on computed tomography (CT). However, the associated ionizing radiation poses long-term risks. Modern artificial intelligence reconstruction algorithms have shown promise in reducing radiation dose while maintaining image quality. Therefore, we aimed to evaluate the dose reduction capabilities of a deep learning-based denoising (DLD) algorithm in traumatic neuroradiological emergency CT scans. MATERIALS AND METHODS: This retrospective single-center study included 100 patients with neuroradiological trauma CT scans. Full-dose (100%) and low-dose (25%) simulated scans were processed using iterative reconstruction (IR2) and DLD. Subjective and objective image quality assessments were performed by four neuroradiologists alongside clinical endpoint analysis. Bayesian sensitivity and specificity were computed with 95% credible intervals. RESULTS: Subjective analysis showed superior scores for 100% DLD compared to 100% IR2 and 25% IR2 (p < 0.001). No significant differences were observed between 25% DLD and 100% IR2. Objective analysis revealed no significant CT value differences but higher noise at 25% dose for DLD and IR2 compared to 100% (p < 0.001). DLD exhibited lower noise than IR2 at both dose levels (p < 0.001). Clinical endpoint analysis indicated equivalence to 100% IR2 in fracture detection for all datasets, with sensitivity losses in hemorrhage detection at 25% IR2. DLD (25% and 100%) maintained comparable sensitivity to 100% IR2. All comparisons demonstrated robust specificity. CONCLUSIONS: The evaluated algorithm enables high-quality, fully diagnostic CT scans at 25% of the initial radiation dose and improves patient care by reducing unnecessary radiation exposure.

Glioma Type Prediction with Dynamic Contrast-Enhanced MR Imaging and Diffusion Kurtosis Imaging-A Standardized Multicenter Study.

The aim was to explore the performance of dynamic contrast-enhanced (DCE) MRI and diffusion kurtosis imaging (DKI) in differentiating the molecular subtypes of adult-type gliomas. A multicenter MRI study with standardized imaging protocols, including DCE-MRI and DKI data of 81 patients with WHO grade 2-4 gliomas, was performed at six centers. The DCE-MRI and DKI parameter values were quantitatively evaluated in ROIs in tumor tissue and contralateral normal-appearing white matter. Binary logistic regression analyses were performed to differentiate between high-grade (HGG) vs. low-grade gliomas (LGG), IDH1/2 wildtype vs. mutated gliomas, and high-grade astrocytic tumors vs. high-grade oligodendrogliomas. Receiver operating characteristic (ROC) curves were generated for each parameter and for the regression models to determine the area under the curve (AUC), sensitivity, and specificity. Significant differences between tumor groups were found in the DCE-MRI and DKI parameters. A combination of DCE-MRI and DKI parameters revealed the best prediction of HGG vs. LGG (AUC = 0.954 (0.900-1.000)), IDH1/2 wildtype vs. mutated gliomas (AUC = 0.802 (0.702-0.903)), and astrocytomas/glioblastomas vs. oligodendrogliomas (AUC = 0.806 (0.700-0.912)) with the lowest Akaike information criterion. The combination of DCE-MRI and DKI seems helpful in predicting glioma types according to the 2021 World Health Organization's (WHO) classification.

MRI-Based Assessment of Risk for Stroke in Moyamoya Angiopathy (MARS-MMA): An MRI-Based Scoring System for the Severity of Moyamoya Angiopathy.

Before revascularization, moyamoya patients require hemodynamic evaluation. In this study, we evaluated the scoring system Prior Infarcts, Reactivity and Angiography in Moyamoya Disease (PIRAMID). We also devised a new scoring system, MRI-Based Assessment of Risk for Stroke in Moyamoya Angiopathy (MARS-MMA), and compared the scoring systems with respect to the capability to predict impaired [15O]water PET cerebral perfusion reserve capacity (CPR). We evaluated 69 MRI, 69 DSA and 38 [15O]water PET data sets. The PIRAMID system was validated by ROC curve analysis with neurological symptomatology as a dependent variable. The components of the MARS-MMA system and their weightings were determined by binary logistic regression analysis. The comparison of PIRAMID and MARS-MMA was performed by ROC curve analysis. The PIRAMID score correlated well with the symptomatology (AUC = 0.784). The MARS-MMA system, including impaired breath-hold-fMRI, the presence of the Ivy sign and arterial wall contrast enhancement, correlated slightly better with CPR impairment than the PIRAMID system (AUC = 0.859 vs. 0.827, Akaike information criterion 140 vs. 146). For simplified clinical use, we determined three MARS-MMA grades without loss of diagnostic performance (AUC = 0.855). The entirely MRI-based MARS-MMA scoring system might be a promising tool to predict the risk of stroke.

Viabahn endoprosthesis for femoropopliteal aneurysm repair: safety, success rates, and long-term patency.

BACKGROUND: The Viabahn endoprosthesis has become a vital option for endovascular therapy, yet there is limited long-term data on its effectiveness for peripheral aneurysm repair. This study aimed to evaluate the safety, technical and clinical success, and long-term patency of the Viabahn endoprosthesis for treating femoropopliteal aneurysms. METHODS: This retrospective tertiary single-center study analyzed patients who underwent a Viabahn endoprosthesis procedure for femoropopliteal aneurysm repair from 2010 to 2020. Intraoperative complications, technical and clinical success rates, and major adverse events (MAE, including acute thrombotic occlusion, major amputation, myocardial infarction, and device- or procedure-related death) at 30 days were assessed. Incidence of clinically-driven target lesion revascularisation (cdTLR) was noted. Patency rates were evaluated by Kaplan-Meier analysis. RESULTS: Among 19 patients (mean age, 72 ± 12 years; 18 male, 1 female) who underwent aneurysm repair using the Viabahn endoprosthesis, there were no intraoperative adverse events, with 100% technical and clinical success rates. At the 30-day mark, all patients (19/19, 100%) were free of MAE. The median follow-up duration was 1,009 days [IQR, 462-1,466]. Popliteal stent graft occlusion occurred in 2/19 patients (10.5%) after 27 and 45 months, respectively. Consequently, the primary patency rates were 100%, 90%, 74% at 12, 24, and 36-72 months, respectively. Endovascular cdTLR was successful in both cases, resulting in sustained secondary patency at 100%. CONCLUSION: The use of Viabahn endoprostheses for femoropopliteal aneurysm repair demonstrated technical and clinical success rates of 100%, a 0% 30-day MAE rate, and excellent long-term patency.

Speeding Up and Improving Image Quality in Glioblastoma MRI Protocol by Deep Learning Image Reconstruction.

A fully diagnostic MRI glioma protocol is key to monitoring therapy assessment but is time-consuming and especially challenging in critically ill and uncooperative patients. Artificial intelligence demonstrated promise in reducing scan time and improving image quality simultaneously. The purpose of this study was to investigate the diagnostic performance, the impact on acquisition acceleration, and the image quality of a deep learning optimized glioma protocol of the brain. Thirty-three patients with histologically confirmed glioblastoma underwent standardized brain tumor imaging according to the glioma consensus recommendations on a 3-Tesla MRI scanner. Conventional and deep learning-reconstructed (DLR) fluid-attenuated inversion recovery, and T2- and T1-weighted contrast-enhanced Turbo spin echo images with an improved in-plane resolution, i.e., super-resolution, were acquired. Two experienced neuroradiologists independently evaluated the image datasets for subjective image quality, diagnostic confidence, tumor conspicuity, noise levels, artifacts, and sharpness. In addition, the tumor volume was measured in the image datasets according to Response Assessment in Neuro-Oncology (RANO) 2.0, as well as compared between both imaging techniques, and various clinical-pathological parameters were determined. The average time saving of DLR sequences was 30% per MRI sequence. Simultaneously, DLR sequences showed superior overall image quality (all p < 0.001), improved tumor conspicuity and image sharpness (all p < 0.001, respectively), and less image noise (all p < 0.001), while maintaining diagnostic confidence (all p > 0.05), compared to conventional images. Regarding RANO 2.0, the volume of non-enhancing non-target lesions (p = 0.963), enhancing target lesions (p = 0.993), and enhancing non-target lesions (p = 0.951) did not differ between reconstruction types. The feasibility of the deep learning-optimized glioma protocol was demonstrated with a 30% reduction in acquisition time on average and an increased in-plane resolution. The evaluated DLR sequences improved subjective image quality and maintained diagnostic accuracy in tumor detection and tumor classification according to RANO 2.0.

Case report: Solitary mass of the sciatic nerve confirmed as a primary extranodal manifestation of diffuse large B-cell lymphoma in a geriatric patient.

Background: Neoplastic lesions affecting peripheral nerves are rare in the general population and, most often, are benign peripheral nerve sheath tumors. However, a minority of lesions represent high-grade malignancies associated with a poor prognosis, such as malignant peripheral nerve sheath tumors (MPNSTs). Very rarely, these tumors represent peripheral non-nerve sheath tumors (PNNSTs), such as hematological neoplasms that impair nerve function. These can be hard to distinguish from MPNSTs and other lesions arising from the nerve itself. In the present case report, we describe a rare case of direct infiltration of nerves by tumor cells of a hematological neoplasm. Methods: We report the case of a 90-year-old woman with acute onset of right-sided foot palsy, sensory loss, and pain, caused by an extensive solitary mass of the sciatic nerve in the thigh. We present and discuss the clinical presentation, multimodal diagnostic procedures, and treatment. Results: MRI of the right thigh and the caudal pelvis revealed a contrast-enhancing lesion infiltrating the sciatic nerve. Additionally performed staging imaging was non-revealing. After multidisciplinary discussion in the neuro-oncology tumor board, a MPNST was suspected and the patient underwent radical tumor resection. However, final histopathology revealed a diffuse large B-cell lymphoma (DLBCL). The patient received adjuvant palliative local radiotherapy which led to acceptable symptom control. Conclusion: Rare PNNSTs, including extranodal manifestations of DLBCL can have similar clinical and radiological diagnostical features as PNSTs. Comprehensive diagnostic workup of contrast-enhancing lesions affecting peripheral nerves including MRI and metabolic imaging are recommended. Discussion in interdisciplinary tumor boards facilitates finding individual treatment approaches.

Viabahn stent graft for arterial injury management: safety, technical success, and long-term outcome.

BACKGROUND: The Viabahn stent graft has emerged as an integral tool for managing vascular diseases, but there is limited long-term data on its performance in emergency endovascular treatment. This study aimed to assess safety, technical success, and long-term efficacy of the Viabahn stent graft in emergency treatment of arterial injury. METHODS: We conducted a retrospective single tertiary centre analysis of patients who underwent Viabahn emergency arterial injury treatment between 2015 and 2020. Indication, intraoperative complications, technical and clinical success, and major adverse events at 30 days were evaluated. Secondary efficacy endpoints were the primary and secondary patency rates assessed by Kaplan-Meier analysis. RESULTS: Forty patients (71 ± 13 years, 19 women) were analyzed. Indications for Viabahn emergency treatment were extravasation (65.0%), arterio-venous fistula (22.5%), pseudoaneurysm (10.0%), and arterio-ureteral fistula (2.5%). No intraoperative adverse events occurred, technical and clinical success rates were 100%. One acute stent graft occlusion occurred in the popliteal artery on day 9, resulting in a 30-day device-related major-adverse-event rate of 2.5%. Median follow-up was 402 days [IQR, 43-1093]. Primary patency rate was 97% (95% CI: 94-100) in year 1, and 92% (95% CI: 86-98) from years 2 to 6. One stent graft occlusion occurred in the external iliac artery at 18 months; successful revascularization resulted in secondary patency rates of 97% (95% CI: 94-100) from years 1 to 6. CONCLUSION: Using Viabahn stent graft in emergency arterial injury treatment had 100% technical and clinical success rates, a low 30-day major-adverse-event rate of 2.5%, and excellent long-term patency rates.

Deep learning-accelerated image reconstruction in back pain-MRI imaging: reduction of acquisition time and improvement of image quality.

INTRODUCTION: Low back pain is a global health issue causing disability and missed work days. Commonly used MRI scans including T1-weighted and T2-weighted images provide detailed information of the spine and surrounding tissues. Artificial intelligence showed promise in improving image quality and simultaneously reducing scan time. This study evaluates the performance of deep learning (DL)-based T2 turbo spin-echo (TSE, T2DLR) and T1 TSE (T1DLR) in lumbar spine imaging regarding acquisition time, image quality, artifact resistance, and diagnostic confidence. MATERIAL AND METHODS: This retrospective monocentric study included 60 patients with lower back pain who underwent lumbar spinal MRI between February and April 2023. MRI parameters and DL reconstruction (DLR) techniques were utilized to acquire images. Two neuroradiologists independently evaluated image datasets based on various parameters using a 4-point Likert scale. RESULTS: Accelerated imaging showed significantly less image noise and artifacts, as well as better image sharpness, compared to standard imaging. Overall image quality and diagnostic confidence were higher in accelerated imaging. Relevant disk herniations and spinal fractures were detected in both DLR and conventional images. Both readers favored accelerated imaging in the majority of examinations. The lumbar spine examination time was cut by 61% in accelerated imaging compared to standard imaging. CONCLUSION: In conclusion, the utilization of deep learning-based image reconstruction techniques in lumbar spinal imaging resulted in significant time savings of up to 61% compared to standard imaging, while also improving image quality and diagnostic confidence. These findings highlight the potential of these techniques to enhance efficiency and accuracy in clinical practice for patients with lower back pain.

Deep learning-accelerated image reconstruction in MRI of the orbit to shorten acquisition time and enhance image quality.

BACKGROUND AND PURPOSE: This study explores the use of deep learning (DL) techniques in MRI of the orbit to enhance imaging. Standard protocols, although detailed, have lengthy acquisition times. We investigate DL-based methods for T2-weighted and T1-weighted, fat-saturated, contrast-enhanced turbo spin echo (TSE) sequences, aiming to improve image quality, reduce acquisition time, minimize artifacts, and enhance diagnostic confidence in orbital imaging. METHODS: In a 3-Tesla MRI study of 50 patients evaluating orbital diseases from March to July 2023, conventional (TSES ) and DL TSE sequences (TSEDL ) were used. Two neuroradiologists independently assessed the image datasets for image quality, diagnostic confidence, noise levels, artifacts, and image sharpness using a randomized and blinded 4-point Likert scale. RESULTS: TSEDL significantly reduced image noise and artifacts, enhanced image sharpness, and decreased scan time, outperforming TSES (p < .05). TSEDL showed superior overall image quality and diagnostic confidence, with relevant findings effectively detected in both DL-based and conventional images. In 94% of cases, readers preferred accelerated imaging. CONCLUSION: The study proved that using DL for MRI image reconstruction in orbital scans significantly cut acquisition time by 69%. This approach also enhanced image quality, reduced image noise, sharpened images, and boosted diagnostic confidence.

Quantitative Flow Measurements of Pelvic Venous Vasculature Using 4D Flow MRI.

RATIONALE AND OBJECTIVES: To evaluate 4D Flow magnetic resonance imaging (MRI) sequences for quantitative flow measurements of the pelvic venous vasculature. MATERIALS AND METHODS: A prospective study of healthy volunteers was performed. After informed consent all subjects underwent 4D flow sequences at a 3 T MRI scanner with different isotropic resolution and different velocity encoding (Venc) settings: (sequence #1) voxel size (VS) 1.63 mm3, Venc 50 cm/s; (sequence #2) VS 1.63 mm3, Venc 100 cm/s and (sequence #3) VS 2.03 mm3, Venc 50 cm/s. Perfusion parameters were calculated for all venous vessel segments starting at the level of the inferior vena cava and extending caudally to the level of the common femoral vein. For reference, arterial flow was calculated using 1.63 mm3 isotropic resolution with a Venc of 100 cm/s. RESULTS: Ten healthy subjects (median age 28 years, interquartile range [IQR]: 26.25-28 years) were enrolled in this study. Median scanning time was 12:12 minutes (IQR 10:22-13:32 minutes) for sequence #1, 11:02 minutes (IQR 9:57-11:19 minutes) for sequence #2 and 6:10 minutes (IQR 5:44-6:47 minutes) for sequence #3. Flow measurements were derived from all sequences. The venous pelvic vasculature showed similar perfusion parameters compared to its arterial counterpart, for example the right common iliac arterial segment showed a perfusion of 8.32 ml/s (IQR: 6.94-10.68 ml/s) versus 7.29 ml/s (IQR: 4.70-8.90 ml/s) in the corresponding venous segment (P = 0.218). The venous flow measurements obtained from the three investigated sequences did not reveal significant differences. CONCLUSION: 4D Flow MRI is suitable for quantitative flow measurement of the venous pelvic vasculature. To reduce the scanning time without compromising quantitative results, the resolution can be decreased while increasing the Venc. This technique may be utilized in the future for the diagnosis and treatment response assessment of iliac vein compression syndromes.

A novel fully automated method for measuring ASPECTS to improve stroke diagnosis: Comparison to traditional ASPECTS.

BACKGROUND AND PURPOSE: To compare the accuracy of subjective Alberta Stroke Program Early CT Score (sASPECTS) evaluation and that of an automated prototype software (aASPECTS) on nonenhanced CT (NECT) in patients with early anterior territory stroke and controls using side-to-side quantification of hypoattenuated brain areas. METHODS: We retrospectively analyzed the NECT scans of 42 consecutive patients with ischemic stroke before reperfusion and 42 controls using first sASPECTS and subsequently aASPECTS. We assessed the differences in Alberta Stroke Program Early CT Score (ASPECTS) and calculated the sensitivity and specificity of NECT with CT perfusion, whereas cerebral blood volume (CBV) served as the reference standard for brain infarction. RESULTS: The clot was located in the middle cerebral artery (MCA) in 47.6% of cases and the internal carotid artery (ICA) in 28.6% of cases. Ten cases presented combined ICA and MCA occlusions. The stroke was right sided in 52.4% of cases and left sided in 47.6%. Reader-based NECT analysis yielded a median sASPECTS of 10. The median CBV-based ASPECTS was 7. Compared to the area of decreased CBV, sASPECTS yielded a sensitivity of 12.5% and specificity of 86.8%. The software prototype (aASPECTS) yielded an overall sensitivity of 65.5% and a specificity of 92.2%. The interreader agreement for ASPECTS evaluation of admission NECT and follow-up CT was almost perfect (κ = .93). The interreader agreement of the CBV color map evaluation was substantial (κ = .77). CONCLUSIONS: aASPECTS of NECT can outperform sASPECTS for stroke detection.

Deep Learning Accelerated Image Reconstruction of Fluid-Attenuated Inversion Recovery Sequence in Brain Imaging: Reduction of Acquisition Time and Improvement of Image Quality.

RATIONALE AND OBJECTIVES: Fluid-attenuated inversion recovery (FLAIR) imaging is playing an increasingly significant role in the detection of brain metastases with a concomitant increase in the number of magnetic resonance imaging (MRI) examinations. Therefore, the purpose of this study was to investigate the impact on image quality and diagnostic confidence of an innovative deep learning-based accelerated FLAIR (FLAIRDLR) sequence of the brain compared to conventional (standard) FLAIR (FLAIRS) imaging. MATERIALS AND METHODS: Seventy consecutive patients with staging cerebral MRIs were retrospectively enrolled in this single-center study. The FLAIRDLR was conducted using the same MRI acquisition parameters as the FLAIRS sequence, except for a higher acceleration factor for parallel imaging (from 2 to 4), which resulted in a shorter acquisition time of 1:39 minute instead of 2:40 minutes (-38%). Two specialized neuroradiologists evaluated the imaging datasets using a Likert scale that ranged from 1 to 4, with 4 indicating the best score for the following parameters: sharpness, lesion demarcation, artifacts, overall image quality, and diagnostic confidence. Additionally, the image preference of the readers and the interreader agreement were assessed. RESULTS: The average age of the patients was 63 ± 11years. FLAIRDLR exhibited significantly less image noise than FLAIRS, with P-values of< .001 and< .05, respectively. The sharpness of the images and the ability to detect lesions were rated higher in FLAIRDLR, with a median score of 4 compared to a median score of 3 in FLAIRS (P-values of<.001 for both readers). In terms of overall image quality, FLAIRDLR was rated superior to FLAIRS, with a median score of 4 vs 3 (P-values of<.001 for both readers). Both readers preferred FLAIRDLR in 68/70 cases. CONCLUSION: The feasibility of deep learning FLAIR brain imaging was shown with additional 38% reduction in examination time compared to standard FLAIR imaging. Furthermore, this technique has shown improvement in image quality, noise reduction, and lesion demarcation.

Enhanced Recovery After Surgery (ERAS) Pathways for Aesthetic Breast Surgery: A Prospective Cohort Study on Patient-Reported Outcomes.

BACKGROUND: Patients' expectations of an anticipated timeline of recovery and fear of anesthesia in aesthetic breast surgery have not been studied. OBJECTIVE: This study aims to assess patient anxiety, expectations, and satisfaction after Enhanced Recovery after Surgery (ERAS) pathways for aesthetic breast surgery and the progress of postoperative recovery. MATERIALS AND METHODS: All consecutive patients who underwent aesthetic breast surgery between April 2021 and August 2022 were included in this single-center prospective cohort study. The ERAS protocol consists of more than 20 individual measures in the pre-, intra-, and postoperative period. Epidemiological data, expectations, and recovery were systematically assessed with standardized self-assessment questionnaires, including the International Pain Outcome Questionnaire (IPO), the BREAST-Q or BODY-Q, and data collection forms. RESULTS: In total, 48 patients with a median of 30 years of age were included. Patients returned to most daily activities within 5 days. Eighty-eight percent of patients were able to accomplish daily activities sooner than expected. The time of return to normal daily activities was similar across all procedure types. There was no statistically significant difference regarding postoperative satisfaction between patients who recovered slower (12%) and patients who recovered as fast or faster (88%) than anticipated (p=0.180). Patients reporting fear of anesthesia in the form of conscious sedation significantly diminished from 17 to 4% postoperatively (p<0.001). CONCLUSION: Enhanced Recovery after Surgery (ERAS) pathways for aesthetic breast surgery are associated with rapid recovery and high patient satisfaction. This survey study provides valuable insight into patients' concerns and perspectives that may be implemented in patient education and consultations to improve patient satisfaction following aesthetic treatments. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Impact of Tracer Dose Reduction in [18 F]-Labelled Fluorodeoxyglucose-Positron Emission Tomography ([18 F]-FDG)-PET) on Texture Features and Histogram Indices: A Study in Homogeneous Tissues of Phantom and Patient.

BACKGROUND: Histogram indices (HIs) and texture features (TFs) are considered to play an important role in future oncologic PET-imaging and it is unknown how these indices are affected by changes of tracer doses. A randomized undersampling of PET list mode data enables a simulation of tracer dose reduction. We performed a phantom study to compare HIs/TFs of simulated and measured tracer dose reductions and evaluated changes of HIs/TFs in the liver of patients with PETs from simulated reduced tracer doses. Overall, 42 HIs/TFs were evaluated in a NEMA phantom at measured and simulated doses (stepwise reduction of [18 F] from 100% to 25% of the measured dose). [18 F]-FDG-PET datasets of 15 patients were simulated from 3.0 down to 0.5 MBq/kgBW in intervals of 0.25 MBq/kgBW. HIs/TFs were calculated from two VOIs placed in physiological tissue of the right and left liver lobe and linear correlations and coefficients of variation analysis were performed. RESULTS: All 42 TFs did not differ significantly in measured and simulated doses (p > 0.05). Also, 40 TFs showed the same behaviour over dose reduction regarding differences in the same group (measured or simulated), and for 26 TFs a linear behaviour over dose reduction for measured and simulated doses could be validated. Out of these, 13 TFs could be identified, which showed a linear change in TF value in both the NEMA phantom and patient data and therefore should maintain the same informative value when transferred in a dose reduction setting. Out of this Homogeneity 2, Entropy and Zone size non-uniformity are of special interest because they have been described as preferentially considerable for tumour heterogeneity characterization. CONCLUSIONS: We could show that there was no significant difference of measured and simulated HIs/TFs in the phantom study and most TFs reveal a linear behaviour over dose reduction, when tested in homogeneous tissue. This indicates that texture analysis in PET might be robust to dose modulations.

Is There Still a Role for Two-Phase Contrast-Enhanced CT and Virtual Monoenergetic Images in the Era of Photon-Counting Detector CT?

BACKGROUND: To compare the diagnostic characteristics between arterial phase imaging versus portal venous phase imaging, applying polychromatic T3D images and low keV virtual monochromatic images using a 1st generation photon-counting CT detector, of CT in patients with hepatocellular carcinoma (HCC). METHODS: Consecutive patients with HCC, with a clinical indication for CT imaging, were prospectively enrolled. Virtual monoenergetic images (VMI) were reconstructed at 40 to 70 keV for the PCD-CT. Two independent, blinded radiologists counted all hepatic lesions and quantified their size. The lesion-to-background ratio was quantified for both phases. SNR and CNR were determined for T3D and low VMI images; non-parametric statistics were used. RESULTS: Among 49 oncologic patients (mean age 66.9 ± 11.2 years, eight females), HCC was detected in both arterial and portal venous scans. The signal-to-noise ratio, the CNR liver-to-muscle, the CNR tumor-to-liver, and CNR tumor-to-muscle were 6.58 ± 2.86, 1.40 ± 0.42, 1.13 ± 0.49, and 1.53 ± 0.76 in the arterial phase and 5.93 ± 2.97, 1.73 ± 0.38, 0.79 ± 0.30, and 1.36 ± 0.60 in the portal venous phase with PCD-CT, respectively. There was no significant difference in SNR between the arterial and portal venous phases, including between "T3D" and low keV images (p > 0.05). CNRtumor-to-liver differed significantly between arterial and portal venous contrast phases (p < 0.005) for both "T3D" and all reconstructed keV levels. CNRliver-to-muscle and CNRtumor-to-muscle did not differ in either the arterial or portal venous contrast phases. CNRtumor-to-liver increased in the arterial contrast phase with lower keV in addition to SD. In the portal venous contrast phase, CNRtumor-to-liver decreased with lower keV; whereas, CNRtumor-to-muscle increased with lower keV in both arterial and portal venous contrast phases. CTDI and DLP mean values for the arterial upper abdomen phase were 9.03 ± 3.59 and 275 ± 133, respectively. CTDI and DLP mean values for the abdominal portal venous phase were 8.75 ± 2.99 and 448 ± 157 with PCD-CT, respectively. No statistically significant differences were found concerning the inter-reader agreement for any of the (calculated) keV levels in either the arterial or portal-venous contrast phases. CONCLUSIONS: The arterial contrast phase imaging provides higher lesion-to-background ratios of HCC lesions using a PCD-CT; especially, at 40 keV. However, the difference was not subjectively perceived as significant.

Definitions of Abnormal Breast Size and Asymmetry: A Cohort Study of 400 Women.

BACKGROUND: Macromastia, micromastia and breast asymmetry have an impact on health and quality of life. However, there is scarce information addressing breast size and asymmetry frequency distribution in reference populations. OBJECTIVE: The current study aims to identify factors that influence breast size and symmetry and classifies abnormal breast sizes and breast asymmetries in an adult German population. METHODS: Breast base dimensions, breast volume, symmetry, and other breast anthropometric parameters of 400 German female patients were determined in a retrospective review of the MRI archives at our institution. Professional medical MRI-segmentation software was used for volume measurement. RESULTS: A total of 400 Patients were retrospectively enrolled. The patients had a mean age of 50 ± 12 years (min: 24; max: 82), mean BMI of 25.0 ± 5.0 (min: 14.7, max: 45.6), and a mean total breast volume of 976 ml (right: 973 ml, min: 64, max: 4777; left: 979 ml, min: 55, max: 4670). The strongest correlation of breast volume was observed with BMI (r = 0.834, p < 0.001), followed by breast base width (r = 0.799, p < 0.001). Smaller breasts have higher breast volume asymmetry ratios (r = - 0.124, p < 0.014). For a BMI between 18.5 and 24.9 kg/m2, micromastia is defined by breast volumes below 250 ml (5th percentile) and macromastia by volumes above 1250 ml (95th percentile). Abnormal breast volume asymmetry (< 5th and > 95th percentile) is equivalent to an absolute difference of approximately 25% relative to the smallest side (bidirectional asymmetry ratio 5th percentile - 19%; 95th percentile 26%). CONCLUSION: This study provides normative data of German women, as well as selected size-for-BMI percentiles and asymmetry ratio percentiles. The normative data may help to establish transparent and objective coverage criteria for health insurances. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Quantification of Facial Fat Compartment Variations: A Three-Dimensional Morphometric Analysis of the Cheek.

BACKGROUND: Cheek contour is a main determinant of facial attractiveness. The aim of this study was to evaluate the relationship between age, sex, and body mass index (BMI) and cheek fat volume in a large cohort to better understand and treat facial aging. METHODS: The authors performed a retrospective review of the archives of the Department of Diagnostic and Interventional Radiology, University Hospital of Tübingen. Epidemiologic data and medical history were assessed. Cheek superficial and deep fat compartment volumes were measured on magnetic resonance images. Statistical analyses were performed using SPSS and SAS statistical software. RESULTS: A total of 87 patients with a mean age of 46 years (range, 18 to 81 years) were included. The superficial and deep fat compartment volumes of the cheek increased with BMI ( P < 0.001 and P = 0.005), but there was no significant relationship between age and volume. The ratio of superficial versus deep fat did not change with age. No significant difference of the superficial or deep fat compartments was found between men and women in a regression analysis ( P = 0.931 and P = 0.057). CONCLUSIONS: Cheek fat volume measurements on magnetic resonance imaging scans using reconstruction software suggest that the fat volume of the cheek increases with BMI but does not change significantly with age. Further studies are needed to elucidate the role of age-related changes of bone structures or sagging of the fat compartments.

Prospective intraindividual comparison of a standard 2D TSE MRI protocol for ankle imaging and a deep learning-based 2D TSE MRI protocol with a scan time reduction of 48.

PURPOSE: Magnetic resonance imaging (MRI) scan time remains a limited and valuable resource. This study evaluates the diagnostic performance of a deep learning (DL)-based accelerated TSE study protocol compared to a standard TSE study protocol in ankle MRI. MATERIAL AND METHODS: Between October 2020 and July 2021 forty-seven patients were enrolled in this study for an intraindividual comparison of a standard TSE study protocol and a DL TSE study protocol either on a 1.5 T or a 3 T scanner. Two radiologists evaluated the examinations regarding structural pathologies and image quality categories (5-point-Likert-scale; 1 = "non diagnostic", 5 = "excellent"). RESULTS: Both readers showed almost perfect/perfect agreement of DL TSE with standard TSE in all analyzed structural pathologies (0.81-1.00) with a median "good" or "excellent" rating (4-5/5) in all image quality categories in both 1.5 T and 3 T MRI. The reduction of total acquisition time of DL TSE compared to standard TSE was 49% in 1.5 T and 48% in 3 T MRI to a total acquisition time of 5 min 41 s and 5 min 46 s. CONCLUSION: In ankle MRI the new DL-based accelerated TSE study protocol delivers high agreement with standard TSE and high image quality, while reducing the acquisition time by 48%.

How Real Are Computed Tomography Low Dose Simulations? An Investigational In-Vivo Large Animal Study.

OBJECTIVES: CT low-dose simulation methods have gained significant traction in protocol development, as they lack the risk of increased patient exposure. However, in-vivo validations of low-dose simulations are as uncommon as prospective low-dose image acquisition itself. Therefore, we investigated the extent to which simulated low-dose CT datasets resemble their real-dose counterparts. MATERIALS AND METHODS: Fourteen veterinarian-sedated alive pigs underwent three CT scans on the same third generation dual-source scanner with 2 months between each scan. At each time, three additional scans ensued, with mAs reduced to 50%, 25%, and 10%. All scans were reconstructed using wFBP and ADMIRE levels 1-5. Matching low-dose datasets were generated from the 100% scans using reconstruction-based and DICOM-based simulations. Objective image quality (CT numbers stability, noise, and signal-to-noise ratio) was measured via consistent regions of interest. Three radiologists independently rated all possible dataset combinations per time point for subjective image quality (-1=inferior, 0=equal, 1=superior). The points were averaged for a semiquantitative score, and inter-rater-agreement was measured using Spearman's correlation coefficient. A structural similarity index (SSIM) analyzed the voxel-wise similarity of the volumes. Adequately corrected mixed-effects analysis compared objective and subjective image quality. Multiple linear regression with three-way interactions measured the contribution of dose, reconstruction mode, simulation method, and rater to subjective image quality. RESULTS: There were no significant differences between objective and subjective image quality of reconstruction-based and DICOM-based simulation on all dose levels (p≥0.137). However, both simulation methods produced significantly lower objective image quality than real-dose images below 25% mAs due to noise overestimation (p<0.001; SSIM≤89±3). Overall, inter-rater-agreement was strong (r≥0.68, mean 0.93±0.05, 95% CI 0.92-0.94; each p<0.001). In regression analysis, significant decreases in subjective image quality were observed for lower radiation doses (b ≤ -0.387, 95%CI -0.399 to -0.358; p<0.001) but not for reconstruction modes, simulation methods, raters, or three-way interactions (p≥0.103). CONCLUSION: Simulated low-dose CT datasets are subjectively and objectively indistinguishable from their real-dose counterparts down to 25% mAs, making them an invaluable tool for efficient low-dose protocol development.