Extravascular findings on run-off MR angiography: frequency, location and clinical significance.

OBJECTIVES: The aim of this study was to analyze the prevalence, location and clinical relevance of extravascular findings (EVFs) on magnetic resonance angiography (MRA) of the run-off vasculature. METHODS: In this retrospective study, we analyzed run-off MRAs of 194 consecutive patients (45 women and 149 men, median age 68 years, IQR 58-74 years). Our patient cohort consisted predominantly of individuals with known (n = 165, 85%) or suspected (n = 15, 8%) peripheral artery disease (PAD). All MRA examinations were performed between 2012 and 2018 on a 3 Tesla MRI scanner using a standardized protocol. Two radiologists re-evaluated the MRA images to identify EVFs, which were classified into findings with major (category I), moderate (category II) and minor (category III) clinical significance. RESULTS: A total of 501 EVFs were found in 172 of the 194 patients (89%). Twenty-seven findings (5%) were assigned to category I, 189 (38%) to category II and 285 (57%) to category III. 23 of 194 patients (12%) had at least one EVF with major clinical relevance (category I). Most of the 27 category I EVFs were observed in the soft tissues (n = 13, 48%). The remaining category I EVFs were found in the musculoskeletal (n = 7, 26%), urogenital (n = 4, 15%), lymphatic (n = 2, 7%) and gastrointestinal (n = 1, 4%) system. The majority of the category I EVFs were infectious (n = 14, 52%) or neoplastic (n = 10, 37%) pathologies. CONCLUSIONS: Clinically relevant EVF can be encountered frequently on run-off MRA examinations. These results illustrate the importance of evaluating all organ systems when reporting MRA examinations, despite the clinical focus being the patients' vascular status.

PI-RADS 2.1 - Image Interpretation: The Most Important Updates and Their Clinical Implications. / PI-RADS 2.1 ­ Befundinterpretation: Die wichtigsten Neuerungen und ihre klinischen Implikationen.

BACKGROUND: Multiparametric magnetic resonance imaging (MRI) of the prostate plays a central role in the diagnosis of patients with suspected prostate cancer. The increasing distribution and application of the guideline for the standardization of image acquisition, evaluation, and reporting (Prostate Imaging - Reporting and Data System, PI-RADS), which was updated in 2019 to version 2.1, contributes to the success of the technique. MATERIALS AND METHODS: The most important updates of PI-RADS version 2.1 presented in 2019 compared to the previous version PI-RADS 2.0 are highlighted and interpreted with regard to their clinical implications. RESULTS: PI-RADS version 2.1 aims to simplify the application of the scoring scheme without changing the basic concept of dominant sequences (DWI in the peripheral zone, T2 in the transition zone). Of particular importance are the increasing role of diffusion-weighted imaging in the transition zone, the now mandatory high b-value of at least 1400 s/mm2, and new information on the assessment of the central zone and the anterior fibromuscular stroma. CONCLUSION: PI-RADS version 2.1 published in 2019 addresses a number of changes to the previous version, including both the examination technique and image interpretation. Prospective clinical studies have yet to prove the extent to which the goals of reducing interreader variability and increasing the detection rate in the transition zone will be achieved. KEY POINTS: · The new PI-RADS version 2.1. includes changes regarding image interpretation and examination technique. · The role of diffusion-weighted imaging is strengthened in the transition zone. · An ultra-high b-value of at least 1400 s/mm2 is mandatory according to PI-RADS 2.1. · Biparametric MRI is not recommended for general application. CITATION FORMAT: · Beyer T, Schlemmer H, Weber M et al. PI-RADS 2.1 - Image Interpretation: The Most Important Updates and Their Clinical Implications. Fortschr Röntgenstr 2021; 193: 787 - 795.

Criteria-Based Imaging and Response Evaluation of Lymphoma 20 Years After Cheson: What is New? / Kriterien-basierte Bildgebung und Responsebeurteilung bei Lymphomen 20 Jahre nach Cheson: Was gibt es Neues?

BACKGROUND: The rapid progress in oncology research requires numerous new scientific publications. This article aims to provide an overview of criteria-based imaging and response evaluation of lymphoma according to the current status of knowledge. In fact, common criteria for evaluating data, especially imaging response evaluation, are essential for comparability of studies. While criteria-based classifications of solid tumors have been established for some time, there are now increasing classifications of lymphoma diseases. The purpose of this review is to describe the development of criteria-based evaluation of lymphoma diseases with a special focus on imaging up to current guidelines. METHODS: Literature review based on PubMed including the languages English and German was performed. This review article includes the most important criteria-based response evaluations of lymphoma published between January 1999 and July 2019. RESULTS AND CONCLUSION: The two latest classifications of response evaluation of lymphoma are: The Lugano classification, which has been steadily developed over the past 20 years and has been specially adapted to technical progress, as well as the evaluation method RECIL (Response Evaluation Criteria In Lymphoma), which is based on the RECIST (Response Evaluation Criteria in Solid Tumors) classification already established for solid tumors. Significant imaging components of both classifications are the anatomical measurement and measurement of the metabolic response of the manifestation of lymphoma using positron emission tomography (PET/CT). KEY POINTS: · Standardized criteria-based response evaluations are essential for the objective and comparable analysis of new drugs for the treatment of lymphoma diseases.. · The latest classification RECIL has significantly simplified treatment evaluation and has established a better comparability to the therapeutic evaluation of solid tumors according to RECIST.. · Further studies will show the most appropriate classifications depending on study settings.. CITATION FORMAT: · Skusa C, Weber M, Böttcher S et al. Criteria-Based Imaging and Response Evaluation of Lymphoma 20 Years After Cheson: What is New?. Fortschr Röntgenstr 2020; 192: 657 - 667.

[Bone tumors and metastases: tips for initial diagnosis and follow-up : Update 2019]. / Knochentumoren und -metastasen: Tipps für Erstdiagnose und Nachsorge : Update 2019.

Benign bone tumors are frequently discovered as incidental findings, whereas malignant tumors and metastases often become clinically noticeable due to pain or swelling. The initial radiological diagnostics by conventional X­ray imaging, magnetic resonance imaging (MRI) and computed tomography (CT) play an important role in the assessment of dignity and further treatment planning. The aftercare of bone tumors is necessary for the recognition of recurrences and distant metastases as well as the detection of complications, e.g. after implantation of a prosthesis. Implanted metal and posttherapeutic alterations can impede the aftercare due to artifacts and treatment-associated tissue alterations. In addition to the recommendations of the Association of the Scientific Medical Societies in Germany (AWMF), the European Organisation for Research and Treatment of Cancer (EORTC) and the European Society of Musculoskeletal Radiology (ESSR), study protocols can be used as orientation for the aftercare of individual primary malignant bone tumors.

The wavelet power spectrum of perfusion weighted MRI correlates with tumor vascularity in biopsy-proven glioblastoma samples.

BACKGROUND: Wavelet transformed reconstructions of dynamic susceptibility contrast (DSC) MR perfusion (wavelet-MRP) are a new and elegant way of visualizing vascularization. Wavelet-MRP maps yield a clear depiction of hypervascular tumor regions, as recently shown. OBJECTIVE: The aim of this study was to elucidate a possible connection of the wavelet-MRP power spectrum in glioblastoma (GBM) with local vascularity and cell proliferation. METHODS: For this IRB-approved study 12 patients (63.0+/-14.9y; 7m) with histologically confirmed IDH-wildtype GBM were included. Target regions for biopsies were prospectively marked on tumor regions as seen on preoperative 3T MRI. During subsequent neurosurgical tumor resection 43 targeted biopsies were taken from these target regions, of which all 27 matching samples were analyzed. All specimens were immunohistochemically analyzed for endothelial cell marker CD31 and proliferation marker Ki67 and correlated to the wavelet-MRP power spectrum as derived from DSC perfusion weighted imaging. RESULTS: There was a strong correlation between wavelet-MRP power spectrum (median = 4.41) and conventional relative cerebral blood volume (median = 5.97 ml/100g) in Spearman's rank-order correlation (κ = .83, p < .05). In a logistic regression model, the wavelet-MRP power spectrum showed a significant correlation to CD31 dichotomized to no or present staining (p = .04), while rCBV did not show a significant correlation to CD31 (p = .30). No significant association between Ki67 and rCBV or wavelet-MRP was found (p = .62 and p = .70, respectively). CONCLUSION: The wavelet-MRP power spectrum derived from existing DSC-MRI data might be a promising new surrogate for tumor vascularity in GBM.

Impact of Collateral Filling Delay on the Development of Subacute Complications After Acute Ischemic Stroke.

PURPOSE: Leptomeningeal collaterals play a pivotal role in acute ischemic stroke. While most collateral scores rely on subjective visual analysis, an objective quantification is possible using dynamic computed tomography (CT) angiography (dynCTA). The aim was to determine the value of collateral filling delay (CFD) as assessed by dynCTA for predicting subacute stroke complications. METHODS: All subjects with isolated prebifurcation middle cerebral artery M1 occlusions were selected from an initial cohort of 2635 patients who underwent multiparametric CT for suspected stroke. The CFD was defined as the difference in time to peak enhancement between M2 segments of both hemispheres. Logistic regression analysis of CFD for space-occupying infarction (≥5 mm shift of brain tissue over the midline), parenchymal hematoma, and hemorrhagic transformation on follow-up imaging was performed. RESULTS: In this study 78 patients (47 female, median age 74 years) were included. The median CFD was 6.31 s (interquartile range [IQR] 4.00-8.64). The CFD values were correlated with qualitative collateral scores (p < 0.05). Higher CFD was associated with the development of space-occupying infarction in univariable (odds ratio, OR = 1.28; p = 0.002) and multivariable regression analysis (OR = 1.48; p = 0.004). The CFD had no association with parenchymal hematoma or hemorrhagic transformation (p > 0.05). CONCLUSION: A high CFD may serve as reproducible measure for collateralization and indicate development of increased risk of space-occupying infarction.

Imaging Features of Bone Tumors: Conventional Radiographs and MR Imaging Correlation.

Imaging bone tumors often causes uncertainty, especially outside dedicated sarcoma treatment centers. Conventional radiography remains the backbone of bone tumor diagnostics, but MR imaging has a role. Radiographs are crucial for assessing the tumor matrix and aggressiveness. MR imaging is the best modality for local staging. This article reviews semiological aspects of bone tumors: patient age, tumor localization, pattern of bone destruction/margins, aggressiveness, growth speed, matrix formation, periosteal reaction, cortical involvement, size, and number of lesions. All aspects are discussed in terms of their appearance on radiographs and MR imaging, with a focus on the correlation between the 2 modalities.

A Radiogenomic Approach for Decoding Molecular Mechanisms Underlying Tumor Progression in Prostate Cancer.

Prostate cancer (PCa) is a genetically heterogeneous cancer entity that causes challenges in pre-treatment clinical evaluation, such as the correct identification of the tumor stage. Conventional clinical tests based on digital rectal examination, Prostate-Specific Antigen (PSA) levels, and Gleason score still lack accuracy for stage prediction. We hypothesize that unraveling the molecular mechanisms underlying PCa staging via integrative analysis of multi-OMICs data could significantly improve the prediction accuracy for PCa pathological stages. We present a radiogenomic approach comprising clinical, imaging, and two genomic (gene and miRNA expression) datasets for 298 PCa patients. Comprehensive analysis of gene and miRNA expression profiles for two frequent PCa stages (T2c and T3b) unraveled the molecular characteristics for each stage and the corresponding gene regulatory interaction network that may drive tumor upstaging from T2c to T3b. Furthermore, four biomarkers (ANPEP, mir-217, mir-592, mir-6715b) were found to distinguish between the two PCa stages and were highly correlated (average r = ± 0.75) with corresponding aggressiveness-related imaging features in both tumor stages. When combined with related clinical features, these biomarkers markedly improved the prediction accuracy for the pathological stage. Our prediction model exhibits high potential to yield clinically relevant results for characterizing PCa aggressiveness.

Clinical and Imaging Parameters Associated With Hyperacute Infarction Growth in Large Vessel Occlusion Stroke.

Background and Purpose- Large vessel occlusion stroke leads to highly variable hyperacute infarction growth. Our aim was to identify clinical and imaging parameters associated with hyperacute infarction growth in patients with an large vessel occlusion stroke of the anterior circulation. Methods- Seven hundred twenty-two consecutive patients with acute stroke were prospectively included in our monocentric stroke registry between 2009 and 2017. We selected all patients with a large vessel occlusion stroke of the anterior circulation, documented times from symptom onset, and CT perfusion on admission for our analysis (N=178). Ischemic core volume was determined with CT perfusion using automated thresholds. Hyperacute infarction growth was defined as ischemic core volume divided by times from symptom onset, assuming linear progression during times from symptom onset to imaging on admission. For collateral assessment, the regional leptomeningeal collateral score (rLMC) was used. Clinical data included the National Institutes of Health Stroke Scale score on admission and cardiovascular risk factors. Regression analysis was performed to adjust for confounders. Results- Median ischemic core volume was 34.4 mL, and median hyperacute infarction growth was 0.27 mL/min. In regression analysis including age, sex, National Institutes of Health Stroke Scale, clot burden score, diabetes mellitus, smoking, hypercholesteremia, hypertension, Alberta Stroke Program Early CT Score, and rLMC scores, only the rLMC score had a significant, independent association with hyperacute infarction growth (adjusted ß=-0.35; P<0.001). Trichotomizing patients by rLMC scores yielded 65 patients with good (rLMC >15), 67 with intermediate (rLMC 11-15) and 46 with poor collaterals (rLMC <11) with an infarction growth of 0.17 mL/min, 0.26 mL/min, and 0.41 mL/min, respectively. Conclusions- Hyperacute infarction growth strongly depends on collaterals. In primary stroke centers, hyperacute infarction growth may be extrapolated to estimate the stroke progression during transfer times to thrombectomy centers and to support decisions on which patients to transfer.

European multicentre study on technical success and long-term clinical outcome of radiofrequency ablation for the treatment of spinal osteoid osteomas and osteoblastomas.

PURPOSE: To evaluate technical success and long-term outcome of CT-guided radiofrequency ablation (RFA) of spinal osteoid osteomas (OO) and osteoblastomas (OB) in six different European centres. METHODS: Eighty-seven patients with spinal OO (77) or OB (10) were treated with CT-guided RFA, after three-dimensional CT-guided access planning. Patient's long-term outcome was assessed by clinical examination and questionnaire-based evaluation including 10-point visual analogue scales (VAS) regarding the effect of RFA on severity of pain and limitations of daily activities. Clinical success was defined as a reduction of > 30% in the VAS score and patient's satisfaction. RESULTS: Overall, RFA was technically successful in 82/87 cases (94.3%) with no major complications; clinical success was achieved in 78/87 cases (89.7%). The OO/OB were localized in the cervical (n = 9/3), the thoracic (n = 27/1), the lumbar (n = 29/4), and the sacral spine (n = 12/2). A decrease in severity of pain after RFA was observed in 86/87 patients (98.9%) with a persistent mean reduction of overall pain score from 8.04 ± 0.96 to 1.46 ± 1.95 (p < 0.001) after a median follow-up time of 29.35 ± 35.59 months. VAS scores significantly decreased for limitations of both daily (5.70 ± 2.73 to 0.67 ± 1.61, p < 0.001) and sports activities (6.40 ± 2.58 to 0.67 ± 1.61, p < 0.001). CONCLUSION: In a multicentric setting, this trial proves RFA to be a safe and efficient method to treat spinal OO/OB and should be regarded as first-line therapy after interdisciplinary case discussion.

Correction to: European multicentre study on technical success and long-term clinical outcome of radiofrequency ablation for the treatment of spinal osteoid osteomas and osteoblastomas.

The original version of this paper contained an error: the Acknowledgements were dropped during early manuscript editing.

Wavelet-based reconstruction of dynamic susceptibility MR-perfusion: a new method to visualize hypervascular brain tumors.

OBJECTIVES: Parameter maps based on wavelet-transform post-processing of dynamic perfusion data offer an innovative way of visualizing blood vessels in a fully automated, user-independent way. The aims of this study were (i) a proof of concept regarding wavelet-based analysis of dynamic susceptibility contrast (DSC) MRI data and (ii) to demonstrate advantages of wavelet-based measures compared to standard cerebral blood volume (CBV) maps in patients with the initial diagnosis of glioblastoma (GBM). METHODS: Consecutive 3-T DSC MRI datasets of 46 subjects with GBM (mean age 63.0 ± 13.1 years, 28 m) were retrospectively included in this feasibility study. Vessel-specific wavelet magnetic resonance perfusion (wavelet-MRP) maps were calculated using the wavelet transform (Paul wavelet, order 1) of each voxel time course. Five different aspects of image quality and tumor delineation were each qualitatively rated on a 5-point Likert scale. Quantitative analysis included image contrast and contrast-to-noise ratio. RESULTS: Vessel-specific wavelet-MRP maps could be calculated within a mean time of 2:27 min. Wavelet-MRP achieved higher scores compared to CBV in all qualitative ratings: tumor depiction (4.02 vs. 2.33), contrast enhancement (3.93 vs. 2.23), central necrosis (3.86 vs. 2.40), morphologic correlation (3.87 vs. 2.24), and overall impression (4.00 vs. 2.41); all p < .001. Quantitative image analysis showed a better image contrast and higher contrast-to-noise ratios for wavelet-MRP compared to conventional perfusion maps (all p < .001). CONCLUSIONS: wavelet-MRP is a fast and fully automated post-processing technique that yields reproducible perfusion maps with a clearer vascular depiction of GBM compared to standard CBV maps. KEY POINTS: • Wavelet-MRP offers high-contrast perfusion maps with a clear delineation of focal perfusion alterations. • Both image contrast and visual image quality were beneficial for wavelet-MRP compared to standard perfusion maps like CBV. • Wavelet-MRP can be automatically calculated from existing dynamic susceptibility contrast (DSC) perfusion data.

Assessment of Loosening and Rotational Malalignment Following Knee Endoprosthesis or Other Surgical Components.

Total knee arthroplasty (TKA) has significant medical and economic implications. The correct placement of the femoral and tibial components is vital to ensure a functional knee and also low failure and revision surgery rates. This article provides the most relevant information regarding knee endoprosthesis from a radiologic point of view. Basic information on the recommended alignment of the femoral and tibial components in TKA and how to measure them are discussed. We then present the most important axial plane rotational references for the femoral and the tibial components. The optimal coronal alignment, illustrating the axes of the lower limb, and loosening as the major complication are also discussed. Finally, we offer a detailed example of rotational assessment.

Towards volumetric thresholds in RECIST 1.1: Therapeutic response assessment in hepatic metastases.

OBJECTIVES: To empirically determine thresholds for volumetric assessment of response and progress of liver metastases in line with the unidimensional RECIST thresholds. METHODS: Patients with metastatic colorectal cancer initially enrolled in a multicentre clinical phase-III trial were included. In all CT scans, the longest axial diameters and volumes of hepatic lesions were determined semi-automatically. The sum of diameters and volumes of 1, ≤2 and ≤5 metastases were compared to all previous examinations. Volumetric thresholds corresponding to RECIST 1.1 thresholds were predicted with loess-regression. In sensitivity analysis, the concordances of proposed thresholds, weight-maximizing thresholds and thresholds from loess-regression were compared. Classification concordance for measurements of ≤2 metastases was further analyzed. RESULTS: For measurements of ≤2 metastases, 348 patients with 629 metastases were included, resulting in 4,773 value pairs. Regression analysis yielded volumetric thresholds of -65.3% for a diameter change of -30%, and +64.6% for a diameter change of +20%. When comparing measurements of unidimensional RECIST assessment with volumetric measurements, there was a concordance of significant progress (≥+20% and ≥+65%) in 88.3% and of significant response (≤-30% and ≤-65%) in 85.0%. CONCLUSIONS: In patients with hepatic metastases, volumetric thresholds of +65% and -65% were yielded corresponding to RECIST thresholds of +20% and -30%. KEY POINTS: • Volumes and diameters of liver metastases from colorectal cancer were determined. • Volumetric thresholds of +65%/-65% corresponding to RECIST 1.1 are proposed. • Comparing both measurements, concordance was 88.3% (significant progress) and 85.0% (significant response).

Early Imaging Prediction of Malignant Cerebellar Edema Development in Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Malignant cerebellar edema (MCE) is a life-threatening complication of acute ischemic stroke that requires timely diagnosis and management. Aim of this study was to identify imaging predictors in initial multiparametric computed tomography (CT), including whole-brain CT perfusion (WB-CTP). METHODS: We consecutively selected all subjects with cerebellar ischemic WB-CTP deficits and follow-up-confirmed cerebellar infarction from an initial cohort of 2635 patients who had undergone multiparametric CT because of suspected stroke. Follow-up imaging was assessed for the presence of MCE, measured using an established 10-point scale, of which scores ≥4 are considered malignant. Posterior circulation-Acute Stroke Prognosis Early CT Score (pc-ASPECTS) was determined to assess ischemic changes on noncontrast CT, CT angiography (CTA), and parametric WB-CTP maps (cerebellar blood flow [CBF]; cerebellar blood volume; mean transit time; time to drain). Fisher's exact tests, Mann-Whitney U tests, and receiver operating characteristics analyses were performed for statistical analyses. RESULTS: Out of a total of 51 patients who matched the inclusion criteria, 42 patients (82.4%) were categorized as MCE- and 9 (17.6%) as MCE+. MCE+ patients had larger CBF, cerebellar blood volume, mean transit time, and time to drain deficit volumes (all with P<0.001) and showed significantly lower median pc-ASPECTS assessed using WB-CTP (CBF, cerebellar blood volume, mean transit time, time to drain; all with P<0.001) compared with MCE- patients, while median pc-ASPECTS on noncontrast CT and CTA was not significantly different (both P>0.05). Receiver operating characteristics analyses yielded the largest area under the curve values for the prediction of MCE development for CBF (0.979) and cerebellar blood volume deficit volumes (0.956) and pc-ASPECTS on CBF (0.935), whereas pc-ASPECTS on noncontrast CT (0.648) and CTA (0.684) had less diagnostic value. The optimal cutoff value for CBF deficit volume was 22 mL, yielding 100% sensitivity and 90% specificity for MCE classification. CONCLUSIONS: WB-CTP provides added diagnostic value for the early identification of patients at risk for MCE development in acute cerebellar stroke.

Global quantification of left ventricular myocardial perfusion at dynamic CT imaging: Prognostic value.

BACKGROUND: There is no published data on the prognostic value of global myocardial perfusion values at stress dynamic CT myocardial perfusion imaging (CTMPI). METHODS: Data of 144 patients from 6 centers who had undergone coronary CT angiography (coronary CTA) and CTMPI were assessed. Coronary CTA studies were acquired at rest; CTMPI was performed under vasodilator stress. Coronary CTA data were evaluated for coronary artery stenosis (≥50% luminal narrowing) on a per-vessel basis. Volumes-of-interest were placed over the entire left ventricular myocardium to obtain global myocardial blood flow (MBF), myocardial blood volume (MBV), and volume transfer constant (Ktrans). Follow-up was obtained at 6/12/18 months. Major adverse cardiac events (MACE, defined as cardiac death, non-fatal myocardial infarction, unstable angina requiring hospitalization, and revascularization) served as the endpoint. RESULTS: MACE occurred in 40 patients (nonfatal myocardial infarction, n = 1, unstable angina, n = 13, PCI, n = 23, and CABG, n = 3). Patients with global MBF of <121 mL/100 mL/min were at increased risk for MACE (HR 2.07, 95% confidence interval [CI]: 1.12-3.84, p = 0.02). This association remained significant after adjusting for age, gender, and clinical risk factors (HR 2.17, 95%CI: 1.16-4.06, p = 0.02), after further adjusting for presence of ≥50% stenosis at coronary CTA (HR 2.18, 95%CI: 1.16-4.10, p = 0.02) and when excluding early (<6 months) revascularizations (HR 2.34, 95%CI: 1.01-5.43, p = 0.0486). Global MBV and Ktrans were not independent predictors of MACE. CONCLUSION: Global quantification of left ventricular MBF at stress dynamic CTMPI may have incremental predictive value for future MACE over clinical risk factors and assessment of stenosis at coronary CTA.

Detection of single-phase CTA occult vessel occlusions in acute ischemic stroke using CT perfusion-based wavelet-transformed angiography.

OBJECTIVES: To determine the detection rate of intracranial vessel occlusions using CT perfusion-based wavelet-transformed angiography (waveletCTA) in acute ischemic stroke patients, in whom single-phase CTA (spCTA) failed to detect an occlusion. METHODS: Subjects were selected from a cohort of 791 consecutive patients who underwent multiparametric CT including whole-brain CT perfusion. Inclusion criteria were (1) significant cerebral blood flow (CBF) deficit, (2) no evidence of vessel occlusion on spCTA and (3) follow-up-confirmed acute ischemic infarction. waveletCTA was independently analysed by two readers regarding presence and location of vessel occlusions. Logistic regression analysis was performed to identify predictors of waveletCTA-detected occlusions. RESULTS: Fifty-nine patients fulfilled the inclusion criteria. Overall, an occlusion was identified using waveletCTA in 31 (52.5 %) patients with negative spCTA. Out of 47 patients with middle cerebral artery infarction, 27 occlusions (57.4 %) were detected by waveletCTA, mainly located in the M2 (15) and M3 segments (8). The presence of waveletCTA-detected occlusions was associated with larger CBF deficit volumes (odds ratio (OR) = 1.335, p = 0.010) and shorter times from symptom onset (OR = 0.306, p = 0.041). CONCLUSIONS: waveletCTA is able to detect spCTA occult vessel occlusions in about half of acute ischemic stroke patients and may potentially identify more patients eligible for endovascular therapy. KEY POINTS: • waveletCTA is able to detect spCTA occult vessel occlusions in stroke patients. • waveletCTA-detected occlusions are associated with larger cerebral blood flow deficits. • waveletCTA has the potential to identify more patients eligible for endovascular therapy. • waveletCTA implies neither additional radiation exposure nor extra contrast agent.

Diagnostic accuracy of whole-brain CT perfusion in the detection of acute infratentorial infarctions.

INTRODUCTION: Although the diagnostic performance of whole-brain computed tomographic perfusion (WB-CTP) in the detection of supratentorial infarctions is well established, its value in the detection of infratentorial strokes remains less well defined. We examined its diagnostic accuracy in the detection of infratentorial infarctions and compared it to nonenhanced computed tomography (NECT), aiming to identify factors influencing its detection rate. METHODS: Out of a cohort of 1380 patients who underwent WB-CTP due to suspected stroke, we retrospectively included all patients with MRI-confirmed infratentorial strokes and compared it to control patients without infratentorial strokes. Two blinded readers evaluated NECT and four different CTP maps independently for the presence and location of infratentorial ischemic perfusion deficits. RESULTS: The study was designed as a retrospective case-control study and included 280 patients (cases/controls = 1/3). WB-CTP revealed a greater diagnostic sensitivity than NECT (41.4 vs. 17.1 %, P = 0.003). The specificity, however, was comparable (93.3 vs. 95.0 %). Mean transit time (MTT) and time to drain (TTD) were the most sensitive (41.4 and 40.0 %) and cerebral blood volume (CBV) the most specific (99.5 %) perfusion maps. Infarctions detected using WB-CTP were significantly larger than those not detected (15.0 vs. 2.2 ml; P = 0.0007); infarct location, however, did not influence the detection rate. CONCLUSION: The detection of infratentorial infarctions can be improved by assessing WB-CTP as part of the multimodal stroke workup. However, it remains a diagnostic challenge, especially small volume infarctions in the brainstem are likely to be missed.

68Ga-PSMA PET/CT Detects the Location and Extent of Primary Prostate Cancer.

We evaluated the accuracy of PET/CT with 68Ga-PSMA-HBED-CC-a 68Ga-conjugated ligand of human prostate-specific membrane antigen (PSMA)-to localize cancer in the prostate and surrounding tissue at initial diagnosis. METHODS: Twenty-one patients with biopsy-proven prostate cancer underwent 68Ga-PSMA-HBED-CC (68Ga-PSMA) PET/CT at a median of 4 d (range, 0-47 d) before radical prostatectomy. Based on a 6-segment model, the Gleason score and proportion of tumor tissue within each segment (segmental tumor burden, or STB) as determined by histopathology (STBHP) were correlated with SUVmax and STB as determined by different SUV cutoffs for 68Ga-PSMA PET (STBPET1-6). Furthermore, the involvement of seminal vesicles and other extracapsular extension were assessed by histopathology and PET/CT. RESULTS: Histopathology-positive segments (n = 100 of 126; 79%) demonstrated a significantly higher mean ± SD SUVmax (11.8 ± 7.6) than histopathology-negative segments (4.9 ± 2.9; P < 0.001). Receiver-operating-characteristic analysis revealed an optimal SUVmax cutoff of 6.5 for discrimination of histopathology-positive segments from histopathology-negative segments (area under the curve, 0.84; P < 0.001), which gave 67% sensitivity, 92% specificity, a 97% positive predictive value, a 42% negative predictive value, and 72% accuracy. STBPET3 as determined by (2 × blood SUV) + (2 × SD) correlated best with STBHP (Pearson ρ = 0.68; P < 0.001; mean difference ± SD, 19% ± 15%). PET/CT correctly detected invasion of seminal vesicles (n = 11 of 21 patients; 52%) with 86% accuracy and tumor spread through the capsule (n = 12; 57%) with 71% accuracy. CONCLUSION: 68Ga-PSMA PET/CT accurately detected the location and extent of primary prostate cancer. Our preliminary findings warrant further investigation of 68Ga-PSMA PET/CT in conjunction with needle biopsy.

Early CT perfusion mismatch in acute stroke is not time-dependent but relies on collateralization grade.

INTRODUCTION: Factors that determine the extent of the penumbra in the initial diagnostic workup using whole brain CT Perfusion (WB-CTP) remain unclear. The purpose of the current study was to determine a possible dependency of the initial mismatch size between cerebral blood flow (CBF) and cerebral blood volume (CBV) from time after symptom onset, leptomeningeal collateralization, and occlusion localization in acute middle cerebral artery (MCA) infarctions. METHODS: Out of an existing cohort of 992 consecutive patients receiving multiparametric CT scans including WB-CTP due to suspected stroke, we included patients who had (1) a witnessed time of symptom onset, (2) an infarction of the MCA territory as documented by follow-up imaging, and (3) an initial CBF volume of >10 ml. CBF and CBV lesion sizes, collateralization grade, and the site of occlusion were determined. RESULTS: We included 103 patients. Univariate analysis showed that time from symptom onset (168 +/- 91.2 min) did not correlate with relative or absolute mismatch volumes (p = 0.458 and p = 0.921). Higher collateralization gradings were associated with small absolute mismatch volumes (p = 0.004 and p < 0.001). Internal carotid artery (ICA) occlusions were associated with large absolute mismatch volumes (p = 0.004). Multivariate analysis confirmed that ICA occlusion was associated with large absolute mismatch volumes (p = 0.005), and high collateral grade was associated with small absolute mismatch volumes (p = 0.017). CONCLUSIONS: There is no significant correlation between initial CTP mismatch and time after symptom onset. Predictors of mismatch size include the extent of the collaterals and a proximal location of the occlusion.