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To analyze possible differences in the inter-reader variability between PI-RADS version 2 (v2) and version 2.1 (v2.1) for the classification of prostate lesions using multiparametric MRI (mpMRI) of the prostate.In this retrospective and randomized study, 239 annotated and histopathologically correlated prostate lesions (104 positive and 135 negative for prostate cancer) were rated twice by three experienced uroradiologists using PI-RADS v2 and v2.1 with an interval of at least two months between readings. Results were tabulated across readers and reading timepoints and inter-reader variability was determined using Fleiss' kappa (κ). Thereafter, an additional analysis of the data was performed in which PI-RADS scores 1 and 2 were combined, as they have the same clinical consequences.PI-PI-RADS v2.1 showed better inter-reader agreement in the peripheral zone (PZ), but poorer inter-reader agreement in the transition zone (TZ) (PZ: κ = 0.63 vs. κ = 0.58; TZ: κ = 0.47 vs. κ = 0.57). When PI-RADS scores 1 and 2 were combined, the use of PI-RADS v2.1 resulted in almost perfect inter-reader agreement in the PZ and substantial agreement in the TZ (PZ: κ = 0.81; TZ: κ = 0.80).PI-RADS v2.1 improves inter-reader agreement in the PZ. New differences in inter-reader agreement were mainly the result of the assignment of PI-RADS v2.1 scores 1 and 2 to lesions in the TZ. Combining scores 1 and 2 improved inter-reader agreement both in the TZ and in the PZ, indicating that refined definitions may be warranted for these PI-RADS scores.· PI-RADSv2.1 improves inter-reader agreement in the PZ but not in the TZ.. · New differences derived from PI-RADSv2.1 scores 1 and 2 in the TZ.. · Combined PI-RADSv2.1 scores of 1 and 2 yielded better inter-reader agreement.. · PI-RADSv2.1 appears to provide more precise description of lesions in the PZ.. · Improved inter-reader agreement in the PZ stresses the importance of appropriate lexicon description..· Beetz N, Haas M, Baur A et al. Inter-Reader Variability Using PI-RADS v2 Versus PI-RADS v2.1: Most New Disagreement Stems from Scores 1 and 2. Fortschr Röntgenstr 2022; 194: 852 - 861.ZIEL: Analyse der möglichen Differenzen in der Interrater-Reliabilität zwischen PI-RADS Version 2 (v2) und Version 2.1 (v2.1) für die Klassifizierung von Prostata-Läsionen in der multiparametrischen MRT (mpMRT) der Prostata.In dieser retrospektiven und randomisierten Studie wurden 239 bereits annotierte und histopathologisch korrelierte Läsionen der Prostata (104 positiv und 135 negativ für Prostatakrebs) zweimal von radiologisch-fachärztlichen Experten für uroradiologische Bildgebung bewertet: zuerst nach PI-RADS v2 und nach einem zeitlichen Intervall von mindestens 2 Monaten anhand der aktualisierten Version PI-RADS v2.1. Die Ergebnisse der Bewerter und Bewertungszeitpunkte wurden kreuztabelliert und die Interrater-Reliabilität wurde mittels Fleiss’ kappa (κ) berechnet. In einer weiteren Analyse wurden die beiden Wertungen mit derselben klinischen Konsequenz PI-RADS-Score 1 und 2 kombiniert und deren Interrater-Reliabilität erneut getestet.PI-RADS v2.1 zeigte eine bessere Interrater-Reliabilität in der peripheren Zone (PZ), aber eine schlechtere Interrater-Reliabilität in der Transitionszone (TZ) (PZ: κ = 0,63 vs. κ = 0,58; TZ: κ = 0,47 vs. κ = 0,57). Die Kombination der PI-RADS-Bewertungen 1 und 2 bei PI-RADS v2.1 resultierte in einer nahezu perfekten Interrater-Reliabilität in der PZ und in einer substantiellen Interrater-Reliabilität in der TZ (PZ: κ = 0,81; TZ: κ = 0,80).PI-RADS v2.1 verbessert die Interrater-Reliabilität in der PZ. Neue Differenzen in der Interrater-Reliabilität bei PI-RADS v2.1 entsprangen hauptsächlich den Läsionen in der TZ, die mit einem Score von 1 oder 2 bewertet wurden. Durch die Kombination der klinisch gleichwertigen PI-RADS-Bewertungen 1 und 2 wird die Interrater-Reliabilität sowohl in der TZ als auch PZ verbessert, sodass eine verbesserte Definition für diese Bewertungen angebracht sein könnte.· PI-RADS v2.1 verbessert Interrater-Reliabilität in der PZ, aber nicht in der TZ.. · Neue Unterschiede entspringen den PI-RADS v2.1-Bewertungen 1 und 2 in der TZ.. · Die Kombination der PI-RADS v2.1-Bewertungen 1 und 2 verbessert die Interrater-Reliabilität.. · PI-RADS v2.1 ermöglicht offenbar eine präzisere Deskription von Läsionen in der PZ.. · Verbesserung der Interrater-Reliabilität in der PZ betont die Bedeutung von geeigneten Deskriptoren..

Preprocedural computed tomography (CT) imaging before transcatheter aortic valve implantation/replacement (TAVI/TAVR) requires high diagnostic accuracy without motion artifacts. The aim of this retrospective study is to compare the image quality of a high-pitch non-electrocardiography (ECG)-gated CT protocol used in patients with atrial tachyarrhythmias with a prospectively ECG-gated CT protocol used in patients with sinus rhythm. We retrospectively included 108 patients who underwent preprocedural CT imaging before TAVI/TAVR. 52 patients with sinus rhythm were imaged using a prospectively ECG-gated protocol (Group A), and 56 patients with atrial tachyarrhythmias were imaged using the high-pitch non-ECG-gated protocol (Group B). Image quality was rated subjectively by two experienced radiologists and assessed by objective parameters including radiation dose, image noise, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) at the levels of the aortic root and abdominal aorta. Subjective image quality was equally good with both CT protocols, and interrater agreement was substantial in both groups but tended to be higher in Group B at the level of the aortic root (Group A: κw = 0.644, Group B: κw = 0.741). With the high-pitch non-ECG-gated CT protocol, image noise was significantly increased (p = 0.001), whereas the SNR, CNR, and radiation dose were significantly decreased (p = 0.002, p = 0.003, and p 0.001, respectively) at the level of the aortic root compared to the prospectively ECG-gated CT protocol. The high-pitch non-ECG-gated protocol yields images with similar subjective image quality compared with the prospectively ECG-gated CT protocol and allows motion-free assessment of the aortic root for accurate TAVI/TAVR planning. The high-pitch non-ECG-gated protocol may be used as an alternative for preprocedural CT imaging in patients with atrial tachyarrhythmias. · In patients with atrial tachyarrhythmias, a high-pitch non-ECG-gated CT protocol achieves similar subjective image quality compared to a prospective ECG-gated CT protocol.. · At the level of the aortic root, image noise is significantly increased, whereas SNR and CNR are significantly decreased using the high-pitch non-ECG-gated protocol.. · Radiation dose is reduced by 55 % using the high-pitch non-ECG-gated protocol..· Shnayien S, Beetz N, Bressem KK et al. Comparison of a High-Pitch Non-ECG-Gated and a Prospective ECG-Gated Protocol for Preprocedural Computed Tomography Imaging Before TAVI/TAVR. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1898-6504.ZIEL: Die präinterventionelle Bildgebung mittels Computertomografie (CT) vor geplanter Transkatheter-Aortenklappen-Implantation (TAVI) erfordert eine hohe diagnostische Genauigkeit ohne Bewegungsartefakte. Ziel dieser retrospektiven Studie ist es, die Bildqualitäten eines „high-pitch“ nicht Elektrokardiogramm (EKG)-getriggerten CT-Protokolls bei Patienten mit atrialer Tachyarrhythmie und eines prospektiv EKG-getriggerten CT-Protokolls bei Patienten mit Sinusrhythmus zu vergleichen. Es wurden 108 Patient*innen mit einer präinterventionellen CT-Bildgebung vor geplanter TAVI retrospektiv eingeschlossen. 52 Patient*innen wurden mit dem prospektiv EKG-getriggerten CT-Protokoll untersucht (Gruppe A), während 56 Patient*innen mit atrialer Tachyarrhythmie mit dem „high pitch“ nicht EKG-getriggerten CT-Protokoll untersucht wurden. Die Bildqualität wurde von 2 erfahrenen Radiologen beurteilt. Zudem wurden die objektiven Bildparameter Strahlendosis, Bildrauschen, Kontrast-Rausch-Verhältnis und Signal-Rausch-Verhältnis auf Höhe der Aortenwurzel und der abdominellen Aorta verglichen. Unabhängig von dem verwendeten CT-Protokoll war die Bildqualität gleich gut und die Interrater-Reliabilität substantiell, aber tendenziell besser in Gruppe B auf Höhe der Aortenwurzel (Gruppe A: κw = 0.644 und Gruppe B: κw = 0.741). Bei der Verwendung des „high-pitch“ nicht EKG-getriggerten CT-Protokolls war das Bildrauschen auf Höhe der Aortenwurzel signifikant erhöht (p = 0.001), wogegen das Kontrast-Rausch-Verhältnis, das Signal-Rausch-Verhältnis sowie die Strahlendosis signifikant reduziert waren (p = 0.002, p = 0.003, und p 0.001) im Vergleich zum prospektiv EKG-getriggerten CT-Protokoll. Das „high-pitch“ nicht EKG-getriggerte CT-Protokoll bietet eine ähnliche subjektive Bildqualität verglichen mit dem prospektiv EKG-getriggerten CT-Protokoll und erlaubt eine bewegungsfreie Beurteilung der Aortenwurzel für eine akkurate TAVI-Planung. Das „high-pitch“ nicht EKG-getriggerte CT-Protokoll könnte eine Alternative für die präinterventionelle CT-Bildgebung bei Patient*innen mit atrialer Tachyarrhythmie darstellen. · Bei Patient*innen mit atrialer Tachyarrhythmie kann das „high-pitch“ nicht EKG-getriggerte CT-Protokoll im Vergleich zu dem EKG-getriggerten CT-Protokoll eine vergleichbare subjektive Bildqualität erzeugen.. · Bei dem „high-pitch“ nicht EKG-getriggerten CT-Protokoll ist das Bildrauschen auf Höhe der Aortenwurzel signifikant erhöht, während das Kontrast-Rausch-Verhältnis und Signal-Rausch-Verhältnis signifikant verringert sind.. · Bei dem „high-pitch“ nicht EKG-getriggerten CT-Protokoll wird die Strahlendosis um 55 % reduziert..

Background Magnetic resonance imaging (MRI) is used to detect the prostate index lesion before targeted biopsy. However, the number of biopsy cores that should be obtained from the index lesion is unclear. The aim of this study is to analyze how many MRI-targeted biopsy cores are needed to establish the most relevant histopathologic diagnosis of the index lesion and to build a prediction model. Methods We retrospectively included 451 patients who underwent 10-core systematic prostate biopsy and MRI-targeted biopsy with sampling of at least three cores from the index lesion. A total of 1587 biopsy cores were analyzed. The core sampling sequence was recorded, and the first biopsy core detecting the most relevant histopathologic diagnosis was identified. In a subgroup of 261 patients in whom exactly three MRI-targeted biopsy cores were obtained from the index lesion, we generated a prediction model. A nonparametric Bayes classifier was trained using the PI-RADS score, prostate-specific antigen (PSA) density, lesion size, zone, and location as covariates. Results The most relevant histopathologic diagnosis of the index lesion was detected by the first biopsy core in 331 cases (73%), by the second in 66 cases (15%), and by the third in 39 cases (9%), by the fourth in 13 cases (3%), and by the fifth in two cases ( Conclusion The most relevant histopathologic diagnosis of the index lesion was made on the basis of three MRI-targeted biopsy cores in 97% of patients. Our classifier can help in predicting the first MRI-targeted biopsy core revealing the most relevant histopathologic diagnosis; however, at least three MRI-targeted biopsy cores should be obtained regardless of the preinterventionally assessed covariates.

Pancreatic cancer is the seventh leading cause of cancer death in both sexes. The aim of this study is to analyze baseline CT body composition using artificial intelligence to identify possible imaging predictors of survival. We retrospectively included 103 patients. First, the presence of surgical treatment and cut-off values for sarcopenia and obesity served as independent variates. Second, the presence of surgery, subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and skeletal muscle index (SMI) served as independent variates. Cox regression analysis was performed for 1-year, 2-year, and 3-year survival. Possible differences between patients undergoing surgical versus nonsurgical treatment were analyzed. Presence of surgery significantly predicted 1-year, 2-year, and 3-year survival (p = 0.01

The Eurotransplant Senior Program allocates kidneys to elderly transplant patients. The aim of this retrospective study is to investigate the use of computed tomography (CT) body composition using artificial intelligence (AI)-based tissue segmentation to predict patient and kidney transplant survival. Body composition at the third lumbar vertebra level was analyzed in 42 kidney transplant recipients. Cox regression analysis of 1-year, 3-year and 5-year patient survival, 1-year, 3-year and 5-year censored kidney transplant survival, and 1-year, 3-year and 5-year uncensored kidney transplant survival was performed. First, the body mass index (BMI), psoas muscle index (PMI), skeletal muscle index (SMI), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) served as independent variates. Second, the cut-off values for sarcopenia and obesity served as independent variates. The 1-year uncensored and censored kidney transplant survival was influenced by reduced PMI (p = 0.02 and p = 0.03, respectively) and reduced SMI (p = 0.01 and p = 0.03, respectively); 3-year uncensored kidney transplant survival was influenced by increased VAT (p = 0.04); and 3-year censored kidney transplant survival was influenced by reduced SMI (p = 0.05). Additionally, sarcopenia influenced 1-year uncensored kidney transplant survival (p = 0.05), whereas obesity influenced 3-year and 5-year uncensored kidney transplant survival. In summary, AI-based body composition analysis may aid in predicting short- and long-term kidney transplant survival.

Pancreatic cancer is the seventh leading cause of cancer death in both sexes. The aim of this study is to analyze baseline CT body composition using artificial intelligence to identify possible imaging predictors of survival. We retrospectively included 103 patients. First, the presence of surgical treatment and cut-off values for sarcopenia and obesity served as independent variates. Second, the presence of surgery, subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and skeletal muscle index (SMI) served as independent variates. Cox regression analysis was performed for 1-year, 2-year, and 3-year survival. Possible differences between patients undergoing surgical versus nonsurgical treatment were analyzed. Presence of surgery significantly predicted 1-year, 2-year, and 3-year survival (p = 0.01

Angesichts der diagnostischen Komplexitat und der grosen Untersuchungszahlen ergibt sich die Herausforderung fur die moderne Radiologie, klinisch signifikante Prostatakarzinome (PCa) mit hoher Sensitivitat und Spezifitat zu identifizieren sowie eine Uberdiagnostik und Ubertherapie von klinisch nicht signifikanten Karzinomen zu vermeiden. In den internationalen Leitlinien etabliert sich zunehmend die multiparametrische Magnetresonanztomographie (mpMRT) als Standarduntersuchung in der Diagnostik des PCa. Die MRT-Beurteilung nach den PI-RADS-Kriterien durch Radiologen weist eine begrenzte Reproduzierbarkeit auf, sodass die rasanten Entwicklungen der automatisierten Bildanalyse mittels Radiomics oder kunstlicher Intelligenz (KI; Machine Learning, Deep Learning) auf eine weitere Verbesserung der Patientenversorgung hoffen lassen. Die Anwendung von KI konzentriert sich auf die automatisierte Detektion und Klassifikation von PCa-Lasionen und versucht, die Aggressivitat anhand des Gleason-Scores zu stratifizieren. Neueste Studien prasentieren gute bis sehr gute Ergebnisse fur die Befundung der mpMRT mittels Radiomics oder KI. Eine breite klinische Anwendung bleibt jedoch aktuell noch aus. Das wachsende Bewusstsein der Forschungsgesellschaft fur eine strukturierte Datenakquise, die Entwicklung robuster AI-Systeme sowie die zunehmende Akzeptanz gegenuber KI-Algorithmen als diagnostisches Hilfsmittel sind Voraussetzungen fur die klinische Anwendbarkeit dieser Technologien. Wenn die KI diese Hurden uberwindet, kann ihr eine Schlusselrolle in der quantitativen, reproduzierbaren Befundung der Prostata-MRT bei standig ansteigenden Untersuchungsvolumina zukommen.

High-Pitch CT for TAVR Evaluation in Patients not Suitable for ECG-GatingThe use of transcatheter aortic valve replacement (TAVR) has been established to be non-inferior to surgical aortic valve replacement (SAVR). As a result, in the United States, more patients now undergo TAVR than SAVR. It is recommended that preprocedural CT imaging for aortic valve evaluation and optimal sizing should include an ECG-gated scan of, at least, the aortic root. However, many patients suffer from concomitant tachyarrhythmias such as atrial fibrillation, which may seriously degrade the diagnostic accuracy of ECG-gated scans. The aim of the present study is to explore whether a high-pitch non-ECG-gated computed tomography angiography (CTA) of the entire aorta can render similar diagnostic preprocedural images as a standard ECG-gated scan. 108 patients were included. Objective image quality parameters such as image noise, CNR and SNR as well as subjective image quality analysis by two different readers were compared. The results showed a significant increase in image noise at the level of the aortic root with use of the high-pitch protocol (p = 0.001). Otherwise, our study revealed no significant differences in subjective and objective image quality. Diagnostic image quality was achieved in all patients without a record of inaccurate sizing in the surgical reports or subsequent patient histories.

To retrospectively investigate the effectiveness of a novel 3-phase protocol for computed tomography (CT) before transcatheter aortic valve implantation/transcatheter aortic valve replacement (TAVI/TAVR) in terms of radiation dose and image quality. A total of 107 nonrandomized patients (81 ± 7.4 years) scheduled for TAVI/TAVR underwent preprocedural CT on an 80-row CT scanner. 55 patients underwent a combined ECG-synchronized spiral scan of the chest and non-ECG-synchronized spiral scan of the abdomen/pelvis as recommended by the Society of Cardiovascular Computed Tomography (SCCT). 52 patients underwent an updated 3-phase variable helical pitch (vHP3) protocol combining a non-ECG-synchronized spiral scan of the upper thoracic aperture, followed by a prospective ECG-synchronized spiral scan of the heart, and a non-ECG-synchronized abdominal/pelvic spiral scan. The radiation dose was determined from an automatically generated protocol based on the CT dose index (CTDI). Objective image quality in terms of vessel attenuation and image noise was measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was evaluated using a 4-point scale and compared for interrater agreement using Cohen's weighted kappa coefficient (κw). All data were compared and statistically analyzed. Use of the novel 3-phase vHP3 protocol reduced the dose-length product (DLP) from 1256.58 ± 619.05 mGy*cm to 790.90 ± 238.15 mGy*cm, reducing the effective dose (E) from 21.36 ± 10.52 mSv to 13.44 ± 4.05 mSv and size-specific dose estimates (SSDE) from 20.85 ± 7.29 mGy to 13.84 ± 2.94 mGy (p 0.001). There were no significant differences in objective and subjective image quality between the two protocols and between the two readers. The novel 3-phase vHP3 protocol significantly reduces the radiation dose of preprocedural TAVI/TAVR CT without a loss of image quality. · The use of a novel 3-phase protocol for preprocedural TAVI/TAVR CT reduces radiation dose by 37 % compared to a combined ECG-synchronized and non-ECG-synchronized spiral CT protocol.. · Objective image quality remains unaffected as image noise, SNR, and CNR did not differ significantly between the two protocols. The average attenuation of the aortic root and abdominal aorta exceeded 450 HU in both protocols.. · The average subjective image quality ratings were good to excellent for both protocols with almost perfect to substantial interrater agreement..· Shnayien S, Bressem KK, Beetz NL et al. Radiation Dose Reduction in Preprocedural CT Imaging for TAVI/TAVR Using a Novel 3-Phase Protocol: A Single Institution's Experience. Fortschr Röntgenstr 2020; 192: 1174 - 1182.ZIEL: Diese retrospektive Studie untersuchte die Wirksamkeit eines neuen 3-Phasen-Protokolls für die präprozedurale Computertomografie (CT) vor einer Transkatheter-Aortenklappenimplantation (TAVI; engl.: TAVR) in Bezug auf die Strahlenbelastung und diagnostische Bildqualität. 107 nichtrandomisierte Patienten (81 ± 7,4 Jahre) erhielten vor der geplanten TAVI/TAVR eine präinterventionelle CT an einem 80-Zeilen-Gerät. Davon wurden 55 Patienten mit einem kombinierten EKG-synchronisierten und nicht EKG-synchronisierten Spiral-CT-Protokoll entsprechend der Empfehlungen der Society of Cardiovascular Computing Tomography (SCCT) untersucht, während 52 Patienten die CT-Bildgebung nach dem neuen, aktualisierten 3-Phasen-Protokoll (vHP3; variabler Pitch-Faktor 3) erhielten. vHP3 kombiniert eine nicht EKG-synchronisierte Spiral-CT des oberen Thorax mit einer anschließenden EKG-synchronisierten Spiral-CT des Herzens und einer nicht EKG-synchronisierten Abdomen/Becken-Spiral-CT. Die Strahlendosis wurde anhand eines automatisch generierten Protokolls basierend auf dem CT-Dosisindex (CTDI) bestimmt. Die objektive Bildqualität in Bezug auf Gefäßkontrastierung und Bildrauschen wurde gemessen und SNR und CNR berechnet. Die subjektive Bildqualität wurde unter Verwendung einer 4-Punkt-Skala bewertet und mittels Cohens-Kappa-Koeffizienten (κw) auf Interrater-Reliabilität überprüft. Alle Daten wurden verglichen und statistisch ausgewertet. Die Verwendung des neuartigen 3-Phasen-vHP3-Protokolls reduzierte das Dosislängenprodukt (DLP) von 1256,58 ± 619,05 mGy*cm auf 790,90 ± 238,15 mGy*cm, die effektive Dosis (E) von 21,36 ± 10,52 mSv auf 13,44 ± 4,05 mSv und die größenspezifische Dosisabschätzung (SSDE) von 20,85 ± 7,29 mGy auf 13,84 ± 2,94 mGy (p 0,001). Hierunter zeigten sich keine signifikanten Unterschiede in der objektiven und subjektiven Bewertung der Bildqualität zwischen beiden Gruppen. Das neue 3-Phasen-vHP3-Protokoll ermöglicht die Durchführung einer präprozeduralen CT vor TAVI/TAVR mit einer signifikanten Reduzierung der Strahlendosis ohne Minderung der Bildqualität. · Die Verwendung eines neuartigen 3-Phasen-Protokolls für die präprozedurale TAVI-CT reduziert die Strahlendosis um 37 % verglichen mit einem kombinierten EKG-synchronisierten und nicht EKG-synchronisierten Spiral-CT-Protokoll.. · Die objektive Bildqualität bleibt unbeeinträchtigt, da Bildrauschen, SNR und CNR keinen signifikanten Unterschied zwischen beiden Protokollen aufweisen und die durchschnittliche Gefäßkontrastierung der Aorta jeweils 450 HU übersteigt.. · Die subjektive Bildqualität wird für beide Protokolle mit fast perfekter bis zu erheblicher Interrater-Reliabilität als gut bis ausgezeichnet bewertet..

In view of the diagnostic complexity and the large number of examinations, modern radiology is challenged to identify clinically significant prostate cancer (PCa) with high sensitivity and specificity. Meanwhile overdiagnosis and overtreatment of clinically nonsignificant carcinomas need to be avoided.Increasingly, international guidelines recommend multiparametric magnetic resonance imaging (mpMRI) as first-line investigation in patients with suspected PCa.Image interpretation according to the PI-RADS criteria is limited by interobserver variability. Thus, rapid developments in the field of automated image analysis tools, including radiomics and artificial intelligence (AI; machine learning, deep learning), give hope for further improvement in patient care.AI focuses on the automated detection and classification of PCa, but it also attempts to stratify tumor aggressiveness according to the Gleason score. Recent studies present good to very good results in radiomics or AI-supported mpMRI diagnosis. Nevertheless, these systems are not widely used in clinical practice.In order to apply these innovative technologies, a growing awareness for the need of structured data acquisition, development of robust systems and an increased acceptance of AI as diagnostic support are needed. If AI overcomes these obstacles, it may play a key role in the quantitative and reproducible image-based diagnosis of ever-increasing prostate MRI examination volumes.