Giant duodenal diverticulum masquerading as a sealed perforation.

Giant duodenal diverticula are large outpouchings involving all layers of the duodenal wall. Whilst often an incidental finding, giant duodenal diverticula can present with diverticulitis or biliary obstruction. We report a case of a giant duodenal diverticulum that was initially misdiagnosed as a localised duodenal perforation on CT. Additional ultrasound and fluoroscopic imaging demonstrated the final diagnosis of acute cholecystitis. The clinical course of this patient highlights the challenge of recognising a giant duodenal diverticulum and the limitations of solely relying on CT in the context of an acute abdominal presentation.

Developing an understanding of artificial intelligence lung nodule risk prediction using insights from the Brock model.

OBJECTIVES: To determine if predictions of the Lung Cancer Prediction convolutional neural network (LCP-CNN) artificial intelligence (AI) model are analogous to the Brock model. METHODS: In total, 10,485 lung nodules in 4660 participants from the National Lung Screening Trial (NLST) were analysed. Both manual and automated nodule measurements were inputted into the Brock model, and this was compared to LCP-CNN. The performance of an experimental AI model was tested after ablating imaging features in a manner analogous to removing predictors from the Brock model. First, the nodule was ablated leaving lung parenchyma only. Second, a sphere of the same size as the nodule was implanted in the parenchyma. Third, internal texture of both nodule and parenchyma was ablated. RESULTS: Automated axial diameter (AUC 0.883) and automated equivalent spherical diameter (AUC 0.896) significantly improved the accuracy of Brock when compared to manual measurement (AUC 0.873), although not to the level of the LCP-CNN (AUC 0.936). Ablating nodule and parenchyma texture (AUC 0.915) led to a small drop in AI predictive accuracy, as did implanting a sphere of the same size as the nodule (AUC 0.889). Ablating the nodule leaving parenchyma only led to a large drop in AI performance (AUC 0.717). CONCLUSIONS: Feature ablation is a feasible technique for understanding AI model predictions. Nodule size and morphology play the largest role in AI prediction, with nodule internal texture and background parenchyma playing a limited role. This is broadly analogous to the relative importance of morphological factors over clinical factors within the Brock model. KEY POINTS: • Brock lung cancer risk prediction accuracy was significantly improved using automated axial or equivalent spherical measurements of lung nodule diameter, when compared to manual measurements. • Predictive accuracy was further improved by using the Lung Cancer Prediction convolutional neural network, an artificial intelligence-based model which obviates the requirement for nodule measurement. • Nodule size and morphology are important factors in artificial intelligence lung cancer risk prediction, with nodule texture and background parenchyma contributing a small, but measurable, role.

Measurement of Aortic Atherosclerotic Disease Severity: A Novel Tool for Simplified, Objective Disease Scoring Using CT Angiography.

Introduction Vascular calcification is a recognized indicator of cardiovascular morbidity and mortality. Calcium scoring is a widely used tool to measure coronary artery calcification, however has limitations for use elsewhere in the body. There is currently no gold standard for quantifying abdominal aortic calcification (AAC). We propose a simple and reproducible method to assess the severity of AAC using multiplanar reconstruction (MPR) in CT angiograms (CTA). Methods A retrospective analysis of CTAs from 75 patients over two years was performed. Using a novel six-point scoring system, three radiologists independently scored the severity of AAC in the distal abdominal aorta. Interclass correlation (ICC) was used to assess the degree of agreement between the three raters. Calcium scoring of the same region was also calculated for each patient. We used Spearman's rank correlation coefficient to compare the CT calcium score with the corresponding average rater's atheroma score. Results There was significant agreement between raters' scores, with an ICC value = 0.972, 95% (CI 0.959-0.981, p < 0.0001). There was also a strong correlation between an average rater's atheroma score with the corresponding CT calcium score, rho = 0.85 (p < 0.0001). Conclusion The results show excellent reproducibility of scores between radiologists, as well as a strong correlation between this novel scoring tool and calcium scores, indicating that it is a reliable method for the grading of AAC.  We propose that this simple semi-quantitative method could form a widely used system for AAC disease stratification.

Radiomics in predicting treatment response in non-small-cell lung cancer: current status, challenges and future perspectives.

OBJECTIVES: Radiomics is the extraction of quantitative data from medical imaging, which has the potential to characterise tumour phenotype. The radiomics approach has the capacity to construct predictive models for treatment response, essential for the pursuit of personalised medicine. In this literature review, we summarise the current status and evaluate the scientific and reporting quality of radiomics research in the prediction of treatment response in non-small-cell lung cancer (NSCLC). METHODS: A comprehensive literature search was conducted using the PubMed database. A total of 178 articles were screened for eligibility and 14 peer-reviewed articles were included. The radiomics quality score (RQS), a radiomics-specific quality metric emulating the TRIPOD guidelines, was used to assess scientific and reporting quality. RESULTS: Included studies reported several predictive markers including first-, second- and high-order features, such as kurtosis, grey-level uniformity and wavelet HLL mean respectively, as well as PET-based metabolic parameters. Quality assessment demonstrated a low median score of + 2.5 (range - 5 to + 9), mainly reflecting a lack of reproducibility and clinical evaluation. There was extensive heterogeneity between studies due to differences in patient population, cancer stage, treatment modality, follow-up timescales and radiomics workflow methodology. CONCLUSIONS: Radiomics research has not yet been translated into clinical use. Efforts towards standardisation and collaboration are needed to identify reproducible radiomic predictors of response. Promising radiomic models must be externally validated and their impact evaluated within the clinical pathway before they can be implemented as a clinical decision-making tool to facilitate personalised treatment for patients with NSCLC. KEY POINTS: • The included studies reported several promising radiomic markers of treatment response in lung cancer; however, there was a lack of reproducibility between studies. • Quality assessment using the radiomics quality score (RQS) demonstrated a low median total score of + 2.5 (range - 5 to + 9). • Future radiomics research should focus on implementation of standardised radiomics features and software, together with external validation in a prospective setting.

Role of diffusion-weighted imaging in monitoring treatment response following high-intensity focused ultrasound ablation of recurrent sacral chordoma.

Chordoma is the most common malignant tumor of the sacrum and is associated with significant neurologic morbidity. Local recurrence is very common, and the long-term prognosis is poor. High-intensity focused ultrasound (HIFU) is a noninvasive and nonionising ablative therapy that has been successful in treating other tumor types and is being evaluated as a new therapy for sacral chordoma. Contrast-enhanced magnetic resonance imaging is typically used to evaluate tumor perfusion following HIFU; however, its utility is limited in poorly perfused tumors. Diffusion-weighted imaging (DWI) provides tissue contrast based on differences in the diffusion of extracellular water without using gadolinium-based contrast agents. We present novel DWI findings following a planned partial HIFU ablation of a large sacral chordoma which had recurred after radiotherapy. Following HIFU, the treated tumor volume demonstrated loss of restriction on DWI correlating with photopenia on positron emission tomography. This suggests successful ablation and tumor necrosis. This novel finding may provide guidance for sequence selection when evaluating HIFU therapy for sacral chordoma and other tumor types for which contrast-enhanced magnetic resonance imaging may have limited utility.

Clinical significance of prostate 18F-labelled fluorodeoxyglucose uptake on positron emission tomography/computed tomography: A five-year review.

AIM: To determine the significance and need for investigation of incidental prostatic uptake in men undergoing 18F-labelled fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for other indications. METHODS: Hospital databases were searched over a 5-year period for patients undergoing both PET/CT and prostate magnetic resonance imaging (MRI). For the initial analysis, the prostate was divided into six sectors and suspicious or malignant sectors were identified using MRI and histopathology reports respectively. Maximum and mean 18F-FDG standardised uptake values were measured in each sector by an investigator blinded to the MRI and histopathology findings. Two age-matched controls were selected per case. Results were analysed using a paired t-test and one-way ANOVA. For the second analysis, PET/CT reports were searched for prostatic uptake reported incidentally and these patients were followed up. RESULTS: Over a 5-year period, 15 patients underwent both PET/CT and MRI and had biopsy-proven prostate cancer. Malignant prostatic sectors had a trend to higher 18F-FDG uptake than benign sectors, however this was neither clinically nor statistically significant (3.13 ± 0.58 vs 2.86 ± 0.68, P > 0.05). 18F-FDG uptake showed no correlation with the presence or histopathological grade of tumour. 18F-FDG uptake in cases with prostate cancer was comparable to that from age-matched controls. Forty-six (1.6%) of 2846 PET/CTs over a 5-year period reported incidental prostatic uptake. Of these, 18 (0.6%) were investigated by PSA, 9 (0.3%) were referred to urology, with 3 (0.1%) undergoing MRI and/or biopsy. No cases of prostate cancer were diagnosed in patients with incidental 18F-FDG uptake in our institute over a 5-year period. CONCLUSION: 18F-FDG uptake overlaps significantly between malignant and benign prostatic conditions. Subsequent patient management was not affected by the reporting of incidental focal prostatic uptake in this cohort.