Added value of quantitative, multiparametric 18F-FDG PET/MRI in the locoregional staging of rectal cancer

Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany

To evaluate the current status of the diagnosis of gastrointestinal tumors in Germany by means of a survey of the oncological imaging working group of the German Radiological Society (DRG) with a focus on the CT protocols being used.Radiologists working in outpatient or inpatient care in Germany were invited. The survey was conducted between 10/2022 and 06/2023 using the SurveyMonkey web tool. Questions related to gastrointestinal cancer were asked with regard to the commonly used imaging modalities, body coverage, and contrast agent phases in CT as well as the use of oral or rectal contrast. The results of the survey were analyzed using descriptive statistics.Clear differences were identified regarding the acquired contrast phases in relation to the place of work - outpatient care, smaller hospitals, maximum care hospitals, or university hospitals. Variances were also recognized regarding oral and rectal contrast. Based on the results and international guidelines, proposals for CT protocols were derived.CT protocols in Germany show a heterogeneous picture regarding acquired contrast phases, as well as oral and rectal contrast for the staging of gastrointestinal cancer. Clear recommendations in the respective guidelines would aid in quality assurance and comparability between different centers. · The examination protocols for the staging of gastrointestinal tumors are heterogeneous in Germany.. · The application of oral and rectal contrast is handled differently at the various radiological centers.. · Standardization of imaging should be targeted.. · Gerwing M, Ristow I, Afat S et al. Standardized diagnosis of gastrointestinal tumors: an update regarding the situation in Germany. Rofo 2025; 197: 657-668.

The predicting value of post neoadjuvant treatment magnetic resonance imaging: a meta-analysis

INTRODUCTION

Neoadjuvant therapy has become standard of care for locally advanced rectal cancer patients. It is correlated with improved clinical and pathological outcomes, including significant tumor downstaging and organ preservation in certain patients. Magnetic resonance imaging (MRI), which has become the standard for pre-operative staging, is also used for clinical and pre-operative restaging following pre-operative treatment. In this meta-analysis, we aimed to evaluate the concordance between restaging MRI (following the completion of neoadjuvant therapy) and postoperative pathology result.

METHODS

We conducted a meta-analysis following the PRISMA 2020 guidelines. Two independent reviewers searched PubMed and Google Scholar for studies reporting restaging MRI results compared to pathological outcomes. Outcomes included tumor and nodal staging, circumferential resection margin (CRM) and pathological complete response (pCR).

RESULTS

Out of 25,000 studies found on the initial search; 33 studies were included. The studies were published between 2005 and 2023 and included 4100 patients (57.14% males). The median age was 62.45 years. The median interval between the conclusion of neoadjuvant treatment and the subsequent restaging MRI was 6 weeks (range 4.14-8.8 weeks). The pooled concordance rates between the restaging MRI and the pathological outcomes for ypT stage and ypN stage were 63.9% (54.5%-73.3%, I2 = 96.02%) and 60.9% (42.9%-78.9%, I2 = 98.96%), respectively. The pooled concordance for predicting pathological complete response was 70.4% (53.6%-87.1%, I2 = 98.21%). As for the circumferential resection margin (CRM), the pooled concordance was 78.2.% (71.6%-84.8%, I2 = 83.76%).

CONCLUSIONS

Our findings suggest that the concordance rates between restaging MRI and pathological outcomes in rectal cancer patients following neoadjuvant therapy are limited. Caregivers should take these results into consideration when making clinical decisions about these patients. More data should be gathered about the predictive value of MRI after total neoadjuvant therapy as well as immunotherapy in rectal cancer patients.

PET/MRI in colorectal and anal cancers: an update

Positron emission tomography (PET) in the era of personalized medicine has a unique role in the management of oncological patients and offers several advantages over standard anatomical imaging. However, the role of molecular imaging in lower GI malignancies has historically been limited due to suboptimal anatomical evaluation on the accompanying CT, as well as significant physiological 18F-flurodeoxyglucose (FDG) uptake in the bowel. In the last decade, technological advancements have made whole-body FDG-PET/MRI a feasible alternative to PET/CT and MRI for lower GI malignancies. PET/MRI combines the advantages of molecular imaging with excellent soft tissue contrast resolution. Hence, it constitutes a unique opportunity to improve the imaging of these cancers. FDG-PET/MRI has a potential role in initial diagnosis, assessment of local treatment response, and evaluation for metastatic disease. In this article, we review the recent literature on FDG-PET/MRI for colorectal and anal cancers; provide an example whole-body FDG-PET/MRI protocol; highlight potential interpretive pitfalls; and provide recommendations on particular clinical scenarios in which FDG-PET/MRI is likely to be most beneficial for these cancer types.

Artificial intelligence with magnetic resonance imaging for prediction of pathological complete response to neoadjuvant chemoradiotherapy in rectal cancer: A systematic review and meta-analysis

Purpose

The purpose of this study was to evaluate the diagnostic accuracy of artificial intelligence (AI) models with magnetic resonance imaging(MRI) in predicting pathological complete response(pCR) to neoadjuvant chemoradiotherapy (nCRT) in patients with rectal cancer. Furthermore, assessed the methodological quality of the models.

Methods

We searched PubMed, Embase, Cochrane Library, and Web of science for studies published before 21 June 2022, without any language restrictions. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) and Radiomics Quality Score (RQS) tools were used to assess the methodological quality of the included studies. We calculated pooled sensitivity and specificity using random-effects models, I² values were used to measure heterogeneity, and subgroup analyses to explore potential sources of heterogeneity.

Results

We selected 21 papers for inclusion in the meta-analysis from 1562 retrieved publications, with a total of 1873 people in the validation groups. The meta-analysis showed that AI models based on MRI predicted pCR to nCRT in patients with rectal cancer: a pooled area under the curve (AUC) 0.91 (95% CI, 0.88-0.93), sensitivity of 0.82(95% CI,0.71-0.90), pooled specificity 0.86(95% CI,0.80-0.91). In the subgroup analysis, the pooled AUC of the deep learning(DL) model was 0.97, the pooled AUC of the radiomics model was 0.85; the pooled AUC of the combined model with clinical factors was 0.92, and the pooled AUC of the radiomics model alone was 0.87. The mean RQS score of the included studies was 10.95, accounting for 30.4% of the total score.

Conclusions

Radiomics is a promising noninvasive method with high value in predicting pathological response to nCRT in patients with rectal cancer. DL models have higher predictive accuracy than radiomics models, and combined models incorporating clinical factors have higher diagnostic accuracy than radiomics models alone. In the future, prospective, large-scale, multicenter investigations using radiomics approaches will strengthen the diagnostic power of pCR.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021285630.