Multitask Weakly Supervised Generative Network for MR-US Registration.

Registering pre-operative modalities, such as magnetic resonance imaging or computed tomography, to ultrasound images is crucial for guiding clinicians during surgeries and biopsies. Recently, deep-learning approaches have been proposed to increase the speed and accuracy of this registration problem. However, all of these approaches need expensive supervision from the ultrasound domain. In this work, we propose a multitask generative framework that needs weak supervision only from the pre-operative imaging domain during training. To perform a deformable registration, the proposed framework translates a magnetic resonance image to the ultrasound domain while preserving the structural content. To demonstrate the efficacy of the proposed method, we tackle the registration problem of pre-operative 3D MR to transrectal ultrasonography images as necessary for targeted prostate biopsies. We use an in-house dataset of 600 patients, divided into 540 for training, 30 for validation, and the remaining for testing. An expert manually segmented the prostate in both modalities for validation and test sets to assess the performance of our framework. The proposed framework achieves a 3.58 mm target registration error on the expert-selected landmarks, 89.2% in the Dice score, and 1.81 mm 95th percentile Hausdorff distance on the prostate masks in the test set. Our experiments demonstrate that the proposed generative model successfully translates magnetic resonance images into the ultrasound domain. The translated image contains the structural content and fine details due to an ultrasound-specific two-path design of the generative model. The proposed framework enables training learning-based registration methods while only weak supervision from the pre-operative domain is available.

Does experience change the role of systematic biopsy during MRI-fusion biopsy of the prostate?

PURPOSE: To determine the role of biopsy experience regarding a potential benefit of additional systematic biopsies and fusion failures during MRI-targeted biopsy of the prostate. SUBJECTS/PATIENTS AND METHODS: We retrospectively evaluated 576 men undergoing transrectal (MRI)-targeted biopsy of the prostate by seven residents in urology between November 2019 and March 2022. Benefit of systematic biopsies (detection of ISUP ≥ 2 PCa (clinically significant PCa (csPCa)) solely in systematic biopsies) and fusion failure (detection of csPCa during systematic biopsies in the area of a reported MRI-lesion and no detection of csPCa in targeted biopsy) were compared by growing biopsy experience levels. Multivariable regression analyses were calculated to investigate the association with benefit of systematic biopsies and fusion failure. RESULTS: The overall PCa detection rate was 72% (413/576). A benefit of systematic biopsies was observed in 11% (63/576); of those, fusion failure was seen in 76% (48/63). Benefit of systematic biopsies and fusion failure were more common among residents with very low experience compared to highly experienced residents (18% versus 4%, p = 0.026; 13% versus 3%, p = 0.015, respectively). Increasing biopsy experience was associated with less benefit from systematic biopsies (OR: 0.98, 95% CI 0.97-0.99) and less fusion failure (OR: 0.98, 95% CI 0.97-0.99). CONCLUSIONS: The benefit of systematic biopsies following targeted biopsy decreases with growing biopsy experience. The higher risk of fusion failure among inexperienced residents necessitates systematic biopsies to ensure the detection of csPCa. Further prospective trials are warranted before a targeted only approach can be recommended in routine clinical practice.

[68Ga-PSMA-11 PET/mpMRI for local detection of primary prostate cancer in men with a negative prior biopsy]. / 68Ga-PSMA-11 PET/mpMRT zur Lokaldetektion des primären Prostatakarzinom bei Männern mit negativer Vorbiopsie.

INTRODUCTION AND OBJECTIVE: Multiparametric MRI (mpMRI) represents the current gold standard for the detection of primary prostate cancer (PC) after a negative biopsy. PSMA PET imaging has been introduced in the diagnostic work-up of PC with high accuracy, but is currently mainly utilised in the setting of biochemical recurrence. This study aimed to determine the efficacy of combined 68Ga-PSMA-11 PET/mpMRI imaging to detect PC in patients with previously negative prostate biopsies. METHODS: A total of 57 patients who had undergone at least one prior negative prostate biopsy were included in this retrospective analysis. All patients underwent 68Ga-PSMA-11 PET/mpMRI imaging of the prostate. mpMRI was evaluated according to the PIRADS classification system and 68Ga-PSMA-11 PET was rated on a 5-point Likert scale (1: PC highly unlikely; 2: PC unlikely; 3: presence of PC is equivocal; 4: PC likely; 5: PC highly likely). All patients received a systematic random biopsy as well as a targeted transrectal biopsy of lesions suspicious on imaging. Imaging and histological biopsy outcomes were compared on a per-patient basis. RESULTS: In the histological analysis, 35/57 (61.4 %) patients harboured PC lesions. In patients with biopsy-proven PC, 21/35 (60.0 %) had a PI-RADS 4 or 5 lesion on mpMRI and 28 /35 (80.0 %) had a PET rating of 4 or 5. Combined 68Ga-PSMA-11 PET/mpMRI missed only one patient with a Gleason score (GS) 7a tumour (rating of 1 or 2 in both PET and mpMRI). Limitations include the retrospective analysis as well as possible false negative biopsy results even in a fusion biopsy setting. CONCLUSION: In this initial analysis, the combined 68Ga-PSMA-11 PET/mpMRI proved to be a valuable imaging tool to guide prostate biopsies for the detection of PC in patients with a negative prior biopsy. In this approach, 68Ga-PSMA-11 PET and mpMRI show partially complementary findings that enhance the detection of PC lesions.

Role of T cells for cytokine production and outcome in a model of acute septic peritonitis.

Although it is generally accepted that early defense mechanisms are controlled by cells of the innate immune system, T cells were found to be crucial for host resistance against acute septic peritonitis. However, the mechanisms by which T cells mediate protection are not fully understood. Here, we demonstrate mice deficient for recombinase-activating gene (RAG) 1, which lack mature B and T cells, showed enhanced susceptibility and impaired bacterial clearance in a model of acute septic peritonitis. Whereas B-cell-deficient muMT mice showed no significant difference in the survival rate after peritonitis induction, T-cell-deficient Balb/c nude mice exhibited reduced survival. Importantly, analysis of cytokine production in both RAG-1-deficient and T-cell-deficient nude mice indicated strongly attenuated production of IL-12, interferon (IFN) gamma, and IL-10 during sepsis. Reduced cytokine levels were detected both in serum and in organ extracts of septic mice. Direct analysis of T cells isolated from septic mice demonstrated that T cells respond to an acute septic challenge by increased production of IFN-gamma and IL-10. Moreover, bacterial numbers in spleens of septic RAG-1-deficient mice were significantly increased as compared with controls, suggesting that T cells are engaged in the early antibacterial immune defense during sepsis, possibly via the production of IFN-gamma. In summary, these results imply that T cells contribute to protective immune responses against acute systemic infections via their ability to produce crucial immune mediators.