A Deep Learning Framework with Explainability for the Prediction of Lateral Locoregional Recurrences in Rectal Cancer Patients with Suspicious Lateral Lymph Nodes.

Malignant lateral lymph nodes (LLNs) in low, locally advanced rectal cancer can cause (ipsi-lateral) local recurrences ((L)LR). Accurate identification is, therefore, essential. This study explored LLN features to create an artificial intelligence prediction model, estimating the risk of (L)LR. This retrospective multicentre cohort study examined 196 patients diagnosed with rectal cancer between 2008 and 2020 from three tertiary centres in the Netherlands. Primary and restaging T2W magnetic resonance imaging and clinical features were used. Visible LLNs were segmented and used for a multi-channel convolutional neural network. A deep learning model was developed and trained for the prediction of (L)LR according to malignant LLNs. Combined imaging and clinical features resulted in AUCs of 0.78 and 0.80 for LR and LLR, respectively. The sensitivity and specificity were 85.7% and 67.6%, respectively. Class activation map explainability methods were applied and consistently identified the same high-risk regions with structural similarity indices ranging from 0.772-0.930. This model resulted in good predictive value for (L)LR rates and can form the basis of future auto-segmentation programs to assist in the identification of high-risk patients and the development of risk stratification models.

Prospective analysis of clinically significant prostate cancer detection with [18F]DCFPyL PET/MRI compared to multiparametric MRI: a comparison with the histopathology in the radical prostatectomy specimen, the ProStaPET study.

PURPOSE: Multiparametric magnetic resonance imaging (mpMRI) is a well-established imaging method for localizing primary prostate cancer (PCa) and for guiding targeted prostate biopsies. [18F]DCFPyL positron emission tomography combined with MRI (PSMA-PET/MRI) might be of additional value to localize primary PCa. The aim of this study was to assess the diagnostic performance of [18F]DCFPyL-PET/MRI vs. mpMRI in tumour localization based on histopathology after robot-assisted radical-prostatectomy (RARP), also assessing biopsy advice for potential image-guided prostate biopsies. METHODS: Thirty prospectively included patients with intermediate to high-risk PCa underwent [18F]DCFPyL-PET/MRI and mpMRI prior to RARP. Two nuclear medicine physicians and two radiologists assessed tumour localization on [18F]DCFPyL-PET/MRI and on mpMRI respectively, and gave a prostate biopsy advice (2 segments) using a 14-segment model of the prostate. The uro-pathologist evaluated the RARP specimen for clinically significant PCa (csPCa) using the same model. csPCa was defined as any PCa with Grade Group (GG) ≥ 2. The biopsy advice based on imaging was correlated with the final histology in the RARP specimen for a total-agreement analysis. An additional near-agreement correlation was performed to approximate clinical reality. RESULTS: Overall, 142 of 420 (33.8%) segments contained csPCa after pathologic examination. The segments recommended for targeted biopsy contained the highest GG PCa segment in 27/30 patients (90.0%) both for [18F]DCFPyL-PET/MRI and mpMRI. Areas under the receiver operating characteristics curves (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the total-agreement detection of csPCa per segment using [18F]DCFPyL-PET/MRI were 0.70, 50.0%, 89.9%, 71.7%, and 77.9%, respectively. These results were 0.75, 54.2%, 94.2%, 82.8%, and 80.1%, respectively, for mpMRI only. CONCLUSION: Both [18F]DCFPyL-PET/MRI and mpMRI were only partly able to detect csPCa on a per-segment basis. An accurate detection (90.0%) of the highest GG lesion at patient-level was observed when comparing both [18F]DCFPyL-PET/MRI and mpMRI biopsy advice with the histopathology in the RARP specimen. So, despite the finding that [18F]DCFPyL-PET/MRI adequately detects csPCa, it does not outperform mpMRI.

Indeterminate Liver Lesions in Patients With Early Stage Rectal Cancer: Can They Be Ignored?

PURPOSE: Small, hypoattenuating, indeterminate liver lesions are often encountered during staging computed tomography (CT) in patients with early-stage rectal cancer. This study aimed to determine the incidence and prognostic significance of these lesions. METHODS AND MATERIALS: A single institution's colorectal cancer (CRC) database was searched for patients with early-stage rectal cancer, defined as a cT1-2N0 tumor on magnetic resonance imaging (MRI). Abdominal CT scans of these patients were assessed for the presence of liver lesions and categorized according to their morphology. Preoperative MRI scans of the liver and abdominal follow-up imaging were assessed to determine whether the liver lesions found during staging CT appeared to be CRC metastases or not. RESULTS: In a consecutive cohort of 1232 patients with CRC who had undergone surgery, 84 patients with early-stage rectal cancer (cT1-2N0 on MRI) were identified. Of those 84 patients, 45 (54%) had 1 or more liver lesions on staging CT; a total of 122 liver lesions were observed, consisting of 95 indeterminate lesions (78%), 25 cysts (20%), and 2 hemangiomas (2%). Preoperative MRI of the liver and regular follow-up imaging revealed no synchronous or metachronous liver metastases in this cohort. CONCLUSIONS: In this study, small, hypoattenuating, indeterminate lesions of the liver were common in patients diagnosed with early rectal cancer and seemed to have no clinical significance. Additional preoperative imaging or follow-up imaging for indeterminate liver lesions in such patients may be unnecessary.

Dealing with indeterminate pulmonary nodules in colorectal cancer patients; a systematic review.

INTRODUCTION: Indeterminate pulmonary nodules (IPNs) are frequently encountered on staging computed tomography (CT) in colorectal cancer (CRC) patients and they create diagnostic dilemmas. This systematic review and pooled analysis aims to estimate the incidence and risk of malignancy of IPNs and provide an overview of the existing literature on IPNs in CRC patients. MATERIALS AND METHODS: EMBASE, Pubmed and the Cochrane database were searched for papers published between January 2005 and April 2020. Studies describing the incidence of IPNs and the risk of malignancy in CRC patients and where the full text was available in the English language were considered for inclusion. Exclusion criteria included studies that used chest X-ray instead of CT, liver metastasis cohorts, studies with less than 60 CRC patients and reviews. RESULTS: A total of 18 studies met the inclusion criteria, involving 8637 patients. Pooled analysis revealed IPNs on staging chest CT in 1327 (15%) of the CRC patients. IPNs appeared to be metastatic disease during follow up in 16% of these patients. Regional lymph node metastases, liver metastases, location of the primary tumour in the rectum, larger IPN size and multiple IPNs are the five most frequently reported parameters predicting the risk of malignancy of IPNs. CONCLUSION: A risk stratification model for CRC patients with IPNs is warranted to enable an adequate selection of high risk patients for IPN follow up and to diminish the use of unnecessary repetitive chest CT-scans in the many low risk patients.

Single Coronary Artery Demonstrating Slightly Decreased 13NH3 Stress Flows in its Distal Flow Territories.

A 54-year-old male patient was referred for computed tomography angiography to rule out cardiovascular disease. The examination revealed a single coronary artery originating from the right sinus of Valsalva, extending to the normal left circumflex artery and left anterior descending artery domains. The computed tomography showed only mild coronary sclerosis. The myocardial stress flow on the subsequently performed 13NH3 myocardial perfusion positron emission tomography demonstrated a relative stress flow reduction in the distal segments along the monocoronary. In the presented patient without significant coronary disease and a benign course of the monocoronary, the relative inability to increase blood flow during stress in the distal segments of the artery is a remarkable finding.