Performance of an ultra-fast deep-learning accelerated MRI screening protocol for prostate cancer compared to a standard multiparametric protocol.

OBJECTIVES: To establish and evaluate an ultra-fast MRI screening protocol for prostate cancer (PCa) in comparison to the standard multiparametric (mp) protocol, reducing scan time and maintaining adequate diagnostic performance. MATERIALS AND METHODS: This prospective single-center study included consecutive biopsy-naïve patients with suspected PCa between December 2022 and March 2023. A PI-RADSv2.1 conform mpMRI protocol was acquired in a 3 T scanner (scan time: 25 min 45 sec). In addition, two deep-learning (DL) accelerated sequences (T2- and diffusion-weighted) were acquired, serving as a screening protocol (scan time: 3 min 28 sec). Two readers evaluated image quality and the probability of PCa regarding PI-RADSv2.1 scores in two sessions. The diagnostic performance of the screening protocol with mpMRI serving as the reference standard was derived. Inter- and intra-reader agreements were evaluated using weighted kappa statistics. RESULTS: We included 77 patients with 97 lesions (mean age: 66 years; SD: 7.7). Diagnostic performance of the screening protocol was excellent with a sensitivity and specificity of 100%/100% and 89%/98% (cut-off ≥ PI-RADS 4) for reader 1 (R1) and reader 2 (R2), respectively. Mean image quality was 3.96 (R1) and 4.35 (R2) for the standard protocol vs. 4.74 and 4.57 for the screening protocol (p < 0.05). Inter-reader agreement was moderate (κ: 0.55) for the screening protocol and substantial (κ: 0.61) for the multiparametric protocol. CONCLUSION: The ultra-fast screening protocol showed similar diagnostic performance and better imaging quality compared to the mpMRI in under 15% of scan time, improving efficacy and enabling the implementation of screening protocols in clinical routine. CLINICAL RELEVANCE STATEMENT: The ultra-fast protocol enables examinations without contrast administration, drastically reducing scan time to 3.5 min with similar diagnostic performance and better imaging quality. This facilitates patient-friendly, efficient examinations and addresses the conflict of increasing demand for examinations at currently exhausted capacities. KEY POINTS: Time-consuming MRI protocols are in conflict with an expected increase in examinations required for prostate cancer screening. An ultra-fast MRI protocol shows similar performance and better image quality compared to the standard protocol. Deep-learning acceleration facilitates efficient and patient-friendly examinations, thus improving prostate cancer screening capacity.

[Explaining radiation dose exposure : The role of the banana equivalent dose compared to the effective dose in patient communication]. / Strahlenexposition erklären : Die Rolle der Bananenäquivalentdosis im Vergleich zur effektiven Dosis im Rahmen der Patientenkommunikation.

BACKGROUND AND OBJECTIVES: Communicating the amount and effects of ionizing radiation to patients prior to an examination using x­rays is associated with challenges: first, calculating the expected dose prior to the examination and, second, quantifying and illustrating cancer risks. Analogies, such as comparing radiation exposure to accident risks, have limitations and may evoke unease. This study explores and compares two new approaches to discuss radiation exposure from common clinical examinations with patients: effective dose and exposure based on radioactive potassium-40 intake from the ingestion of bananas, the banana equivalent dose (BED). MATERIALS AND METHODS: The effective doses of the diagnostic reference levels (DRL) for computed tomography (CT) and X-ray examinations in adults were calculated using mean conversion factors for specific anatomic body regions. For the BED calculation of the diagnostic reference levels, the radiation dose from a conventional banana ingested over 50 years per becquerel was calculated. The outcomes were juxtaposed against an equivalent number of bananas and its respective radiation doses. RESULTS: The calculated doses, namely effective dose and BED, of the German DRL can serve as a reliable metric to discuss radiation exposure from medical imaging with patients prior to an examination. CONCLUSION: This is the first study to calculate the effective doses of the current DRL and to compare these with the pseudoscientific unit BED. While the BED serves as an interesting illustration to metaphorize radiation exposure, it is recommended to use the calculated effective dose of the DRL as the basis for educational consultations with patients.

[German Radiological Society and the Professional Association of German Radiologists position paper on coronary computed tomography: clinical evidence and quality of patient care in chronic coronary syndrome]. / Positionspapier von DRG und BDR zur Computertomographie des Herzens: Klinische Evidenz und Versorgungsqualität beim chronischen Koronarsyndrom.

This position paper is a joint statement of the German Radiological Society (DRG) and the Professional Association of German Radiologists (BDR), which reflects the current state of knowledge about coronary computed tomography (CT). It is based on preclinical and clinical studies that have investigated the clinical relevance as well as the technical requirements and fundamentals of cardiac computed tomography.

The Role of Visceral Obesity, Sarcopenia and Sarcopenic Obesity on Surgical Outcomes After Liver Resections for Colorectal Metastases.

BACKGROUND: The impact of body compositions on surgical results is controversially discussed. This study examined whether visceral obesity, sarcopenia or sarcopenic obesity influence the outcome after hepatic resections of synchronous colorectal liver metastases. METHODS: Ninety-four consecutive patients with primary hepatic resections of synchronous colorectal metastases were identified from a single center database between January 2013 and August 2018. Patient characteristics and 30-day morbidity were retrospectively analyzed. Body fat and skeletal muscle were calculated by planimetry from single-slice CT images at the level of L3. RESULTS: Fifty-nine patients (62.8%) underwent minor hepatectomies, and 35 patients underwent major resections (37.2%). Postoperative complications occurred in 60 patients (62.8%) including 35 patients with major complications (Clavien-Dindo grade III-V). The mortality was nil at 30 days and 2.1% at 90 days. The body mass index showed no influence on postoperative outcomes (p = 1.0). Visceral obesity was found in 66 patients (70.2%) and was significantly associated with overall and major complication rates (p = .002, p = .012, respectively). Sarcopenia was observed in 34 patients (36.2%) without a significant impact on morbidity (p = .461), however, with longer hospital stay. Sarcopenic obesity was found in 18 patients (19.1%) and was significantly associated with postoperative complications (p = .014). Visceral obesity, sarcopenia and sarcopenic obesity were all identified as significant risk factors for overall postoperative complications. CONCLUSION: Visceral obesity, sarcopenic obesity and sarcopenia are independent risk factors for overall complications after resections of CRLM. Early recognition of extremes in body compositions could prompt to perioperative interventions and thus improve postoperative outcomes.

[Value of dual-energy computed tomography for detection of left atrial appendage thrombus]. / Mehrwert der Dual-Energy-Computertomographie zur Detektion von Thromben des linken Vorhofohrs.

OBJECTIVE: Contrast-enhanced computed tomography (CT) is a convenient method to visualize left atrial appendage (LAA) thrombi. We determined whether diagnostic accuracy improves by including dual-energy as compared to transesophageal echocardiography (TEE). Furthermore, the influence of protocol parameters on radiation dose were quantified. METHODS: Patients were assigned to the different CT protocols. All CTs were assessed qualitatively for presence of LAA thrombi and dual-energy CT scans quantitatively for iodine concentration. TEE was assessed qualitatively for the presence of thrombi. RESULTS: Of 32 enrolled patients, 6 had a thrombus in TEE. Qualitative CT assessment yielded 83% sensitivity and 88% specificity. In the 26 patients who underwent dual-energy CT, median iodine concentration was 8.6 mg/cm3 and significantly lower in patients with than without LAA thrombi ; furthermore, it provided value for detecting LAA thrombi (AUC: 0.950 vs 0.867 for combined vs. only qualitative assessment, p = 0.04). The median radiation dose was 1.83 mSv; independently lower in scanning only LAA and with prospective gating , while arrhythmia and dual-energy did not contribute independently. CONCLUSION: CT provides good diagnostic accuracy for detecting LAA thrombi, which can further be improved if iodine density measurements by dual-energy are incorporated. With an optimized protocol, reasonably low radiation dose can be achieved.

A machine-learning framework for automatic reference-free quality assessment in MRI.

Magnetic resonance (MR) imaging offers a wide variety of imaging techniques. A large amount of data is created per examination which needs to be checked for sufficient quality in order to derive a meaningful diagnosis. This is a manual process and therefore time- and cost-intensive. Any imaging artifacts originating from scanner hardware, signal processing or induced by the patient may reduce the image quality and complicate the diagnosis or any image post-processing. Therefore, the assessment or the ensurance of sufficient image quality in an automated manner is of high interest. Usually no reference image is available or difficult to define. Therefore, classical reference-based approaches are not applicable. Model observers mimicking the human observers (HO) can assist in this task. Thus, we propose a new machine-learning-based reference-free MR image quality assessment framework which is trained on HO-derived labels to assess MR image quality immediately after each acquisition. We include the concept of active learning and present an efficient blinded reading platform to reduce the effort in the HO labeling procedure. Derived image features and the applied classifiers (support-vector-machine, deep neural network) are investigated for a cohort of 250 patients. The MR image quality assessment framework can achieve a high test accuracy of 93.7% for estimating quality classes on a 5-point Likert-scale. The proposed MR image quality assessment framework is able to provide an accurate and efficient quality estimation which can be used as a prospective quality assurance including automatic acquisition adaptation or guided MR scanner operation, and/or as a retrospective quality assessment including support of diagnostic decisions or quality control in cohort studies.

On the needle clogging of staked-in-needle pre-filled syringes: Mechanism of liquid entering the needle and solidification process.

Staked-in-needle prefilled syringes (SIN-PFS) are widely used for the parenteral administration of drug product solutions. During stability studies, clogging of the injection needle was observed in syringes filled with concentrated antibody solution. A prerequisite for this phenomenon is that liquid has entered the needle. In this study, we characterized the mechanism causing the entry and movement of liquid in the needle using neutron imaging without manipulating the container closure integrity of the syringe. The gas pressure difference between inside and outside of the syringe was identified as the major cause of liquid movement. The influence of external factors, such as temperature fluctuation and physical pressure on the stopper, were tested and were confirmed to have a relevant impact on the processes of liquid entering and moving inside the injection needle. In a second step, the solidification process of the liquid segments inside the needle via solvent evaporation was further investigated, and the process was found to be dependent on storage time, environmental climate and interaction between the drug product solution and the needle surface. The presence of air/liquid segments was identified as a further factor for the stochastic behavior of needle clogging. For the first time, this fundamental mechanism behind the needle clogging issue was investigated in depth and the results will help to reduce the defect rate for clogged SIN-PFS products.

Clogging in staked-in needle pre-filled syringes (SIN-PFS): Influence of water vapor transmission through the needle shield.

Staked-in needle pre-fillable syringes (SIN-PFS) are a convenient delivery system widely established in the growing pharmaceutical market. Under specific storage conditions, the needle of PFS containing high concentration drug product (DP) solution is prone to clogging, which prevents administration of the liquid. The purpose of this study is to clarify the clogging phenomenon of SIN-PFS and to elucidate the role of water vapor transmission via the needle shield. The presence of liquid within needles is a prerequisite condition for clogging and was investigated non-invasively by neutron imaging (NI) to confirm that liquid can migrate into the needle under certain processing conditions. The water vapor transmission rate (WVTR) of different needle shields was measured and the impact of temperature and relative humidity (rH) on the WVTR was investigated on sheets with the same composition as used in commercial needle shields. Our study clearly showed that the partial vapor pressure difference (ΔPP) across the needle shield is the dominant driving factor for water vapor transmission. A linear correlation between ΔPP and WVTR was found and a model to predict the water vapor transmission for PFS under specific storage conditions was developed. The impact of the WVTR on needle clogging was confirmed by clogging tests performed on SIN-PFS stored under different conditions. Thereby, we clearly show that high water loss induced by higher WVTR can be correlated to an increased occurrence of needle clogging. In conclusion, the WVTR of the needle shield plays a key role in needle clogging and the established WVTR model can be employed to assess the clogging risk for product development.

Aortic Elongation and Stanford B Dissection: The Tübingen Aortic Pathoanatomy (TAIPAN) Project.

OBJECTIVE/BACKGROUND: Aortic elongation has not yet been considered as a potential risk factor for Stanford type B dissection (TBD). The role of both aortic elongation and dilatation in patients with TBD was evaluated. METHODS: The aortic morphology of a healthy control group (n = 236) and patients with TBD (n = 96) was retrospectively examined using three dimensional computed tomography imaging. Curved multiplanar reformats were used to examine aortic diameters at defined landmarks and aortic segment lengths. RESULTS: Diameters at all landmarks were significantly larger in the TBD group. The greatest diameter difference (56%) was measured in dissected descending aortas (p < .001). The segment with the most considerable difference between the study groups with regard to elongation was the non-dissected aortic arch of patients with TBD (36%; p < .001). Elongation in the aortic arch was accompanied by a diameter increase of 21% (p < .001). In receiver-operating curve analysis, the area under the curve was .85 for the diameter and .86 for the length of the aortic arch. CONCLUSIONS: In addition to dilatation, aortic arch elongation is associated with the development of TBD. The diameter and length of the non-dissected aortic arch may be predictive for TBD and may possibly be used for risk assessment in the future. This study provides the basis for further prospective evaluation of these parameters.

Population-Based Imaging and Radiomics: Rationale and Perspective of the German National Cohort MRI Study.

UNLABELLED: The MRI study within the German National Cohort, a large-scale, population-based, longitudinal study in Germany, comprises comprehensive characterization and phenotyping of a total of 30 000 participants using 3-Tesla whole-body MR imaging. A multi-centric study design was established together with dedicated core facilities for e. g. managing incidental findings or providing quality assurance. As such, the study represents a unique opportunity to substantially impact imaging-based risk stratification leading to personalized and precision medicine. Supported by the developments in the field of computational science, the newly developing scientific field of radiomics has large potential for the future. In the present article we provide an overview on population-based imaging and Radiomics and conceptualize the rationale and design of the MRI study within the German National Cohort. KEY POINTS: • Population-based imaging and Radiomics constitute two emerging fields with great oppertunities and challenges for Radiology.• As part of the MRI-study of the NAKO approximately 30 000 subjects will undergo 3 Tesla whole-body MRI.• MR Imaging data is publicly accessable and will provide important insights into the natural history of disease processes and personalized risk profiles of the general population. Citation Format: • Schlett CL, Hendel T, Weckbach S et al. Population-Based Imaging and Radiomics: Rationale and Perspective of the German National Cohort MRI Study. Fortschr Röntgenstr 2016; 188: 652 - 661.

[Diagnostic accuracy of dual energy CT angiography in patients with diabetes mellitus]. / Diagnostische Genauigkeit der Dual-energy-CT-Angiographie bei Patienten mit Diabetes mellitus.

OBJECTIVES: Peripheral arterial disease (PAD) represents a major and highly prevalent complication in patients with diabetes mellitus. The diagnostic, non-invasive work-up by computed tomography angiography (CTA) is limited in the presence of extensive calcification. The aim of the study was to determine the diagnostic accuracy of dual energy CTA (DE-CTA) for the detection and characterization of PAD in patients with diabetes mellitus. MATERIAL AND METHODS: In this study 30 diabetic patients with suspected or known PAD were retrospectively included in the analysis. All subjects underwent DE-CTA (Somatom Definition Flash, Siemens Healthcare, Erlangen, Germany) prior to invasive angiography, which served as the reference standard. Blinded analysis included assessment of the presence and degree of peripheral stenosis on curved multiplanar reformatting (MPR) and maximum intensity projections (MIP). Conventional measures of diagnostic accuracy were derived. RESULTS: Among the 30 subjects included in the analysis (83% male, mean age 70.0 ± 10.5 years, 83% diabetes type 2), the prevalence of critical stenosis in 331 evaluated vessel segments was high (30%). Dual energy CT identified critical stenoses with a high sensitivity and good specificity using curved MPR (100% and 93.1%, respectively) and MIP images (99% and 91.8%, respectively). In stratified analysis, the diagnostic accuracy was higher for stenosis pertaining to the pelvic and thigh vessels as compared with the lower extremities (curved MPR accuracy 97.1% vs. 99.2 vs. 90.9%; respectively, p < 0.001). CONCLUSION: The use of DE-CTA allows reliable detection and characterization of peripheral arterial stenosis in patients with diabetes mellitus with higher accuracy in vessels in the pelvic and thigh regions compared with the vessels in the lower legs.

[Imaging in syndrome complex diabetes mellitus: Current standards and future perspectives]. / Bildgebung im Syndromkomplex Diabetes mellitus : Stellenwert und Chancen.

CLINICAL/METHODICAL ISSUE: Diabetes mellitus is a highly prevalent multisystemic disorder with numerous potential complications and substantial socioeconomic consequences. In many cases, the patient history, physical examination and laboratory tests are not sufficient for a comprehensive evaluation of complicating disorders. STANDARD RADIOLOGICAL METHODS: Imaging modalities, such as sonography, computed tomography (CT) and magnetic resonance imaging (MRI) are of major significance in the evaluation of complicating disorders of diabetes according to current guidelines. Examples include assessment of coronary artery disease, peripheral artery disease, stroke and diabetic foot syndrome. METHODICAL INNOVATIONS: Technical developments allow a substantial reduction in radiation dose and scan time in CT and MRI, respectively and could therefore justify a broader application in this patient population. PERFORMANCE: In the future CT and MRI could also be used for the early detection of diabetic complications. Furthermore, they could also be used for risk stratification, e.g. measurement of hepatic fat content and evaluation of atherosclerosis in whole body MRI. ACHIEVEMENTS: Prior to widespread application of advanced imaging techniques in this patient population, improved outcomes with respect to survival, quality of life and cost-effectiveness need to be demonstrated. PRACTICAL RECOMMENDATIONS: Diagnostic imaging modalities for the evaluation of the syndrome complex of diabetic disorders should be used according to the current guidelines but the use is predicted to increase given the high potential in this population.

X-ray phase-contrast imaging of the breast--advances towards clinical implementation.

Breast cancer constitutes about one-quarter of all cancers and is the leading cause of cancer death in women. To reduce breast cancer mortality, mammographic screening programmes have been implemented in many Western countries. However, these programmes remain controversial because of the associated radiation exposure and the need for improvement in terms of diagnostic accuracy. Phase-contrast imaging is a new X-ray-based technology that has been shown to provide enhanced soft-tissue contrast and improved visualization of cancerous structures. Furthermore, there is some indication that these improvements of image quality can be maintained at reduced radiation doses. Thus, X-ray phase-contrast mammography may significantly contribute to advancements in early breast cancer diagnosis. Feasibility studies of X-ray phase-contrast breast CT have provided images that allow resolution of the fine structure of tissue that can otherwise only be obtained by histology. This implies that X-ray phase-contrast imaging may also lead to the development of entirely new (micro-) radiological applications. This review provides a brief overview of the physical characteristics of this new technology and describes recent developments towards clinical implementation of X-ray phase-contrast imaging of the breast.

Multimodality treatment for early-stage hepatocellular carcinoma: a bridging therapy for liver transplantation.

PURPOSE: To evaluate the efficiency of a multimodality approach consisting of transcatheter arterial chemoembolization (TACE) and radiofrequency ablation (RFA) as bridging therapy for patients with hepatocellular carcinoma (HCC) awaiting orthotopic liver transplantation (OLT) and to evaluate the histopathological response in explant specimens. MATERIALS AND METHODS: Between April 2001 and November 2011, 36 patients with 50 HCC nodules (1.4-5.0 cm, median 2.8 cm) on the waiting list for liver transplantation were treated by TACE and RFA. The drop-out rate during the follow-up period was recorded. The local efficacy was evaluated by histopathological examination of the explanted livers. RESULTS: During a median follow-up time of 29 (4.0-95.3) months the cumulative drop-out rate for the patients on the waiting list was 0, 2.8, 5.5, 11.0, 13.9 and 16.7% at 3, 6, 12, 24, 36 and 48 months, respectively. 16 patients (with 26 HCC lesions) out of 36 (44.4%) were transplanted by the end of study with a median waiting list time of 13.7 (2.5-37.8) months. The histopathological examination of the explanted specimens revealed a complete necrosis in 20 of 26 HCCs (76.9%), whereas 6 (23.1%) nodules showed viable residual tumor tissue. All transplanted patients are alive at a median time of 29.9 months. Imaging correlation showed 100% specificity and 66.7% sensitivity for the depiction of residual or recurrent tumor. CONCLUSION: We conclude that TACE combined with RFA could provide an effective treatment to decrease the drop-out rate from the OLT waiting list for HCC patients. Furthermore, this combination therapy results in high rates of complete tumor necrosis as evaluated in the histopathological analysis of the explanted livers. Further randomized trials are needed to demonstrate if there is a benefit in comparison with a single-treatment approach.

Population imaging as valuable tool for personalized medicine.

Personalized medicine is commonly regarded as an extension of genomic medicine. However, a personalized treatment should not [corrected] be based solely on the presence or absence of genetic factors. Complex imaging methods supplement the diagnostic picture of an individual patient. Comprehensive imaging in population-based settings provides information on reference intervals, the predictive value of subclinical findings, and the complex interrelationships among risk factors, subclinical imaging phenotypes, and diseases.