Diagnostic accuracy of whole-body MRI versus standard imaging pathways for metastatic disease in newly diagnosed colorectal cancer: the prospective Streamline C trial

Abstract

Background Whole-body MRI (WB-MRI) could be an alternative to multimodality staging of colorectal cancer, but its diagnostic accuracy, effect on staging times, number of tests needed, cost, and effect on treatment decisions are unknown. We aimed to prospectively compare the diagnostic accuracy and efficiency of WB-MRI-based staging pathways with standard pathways in colorectal cancer. Methods The Streamline C trial was a prospective, multicentre trial done in 16 hospitals in England. Eligible patients were 18 years or older, with newly diagnosed colorectal cancer. Exclusion criteria were severe systemic disease, pregnancy, contraindications to MRI, or polyp cancer. Patients underwent WB-MRI, the result of which was withheld until standard staging investigations were complete and the first treatment decision made. The multidisciplinary team recorded its treatment decision based on standard investigations, then on the WB-MRI staging pathway (WB-MRI plus additional tests generated), and finally on all tests. The primary outcome was difference in per-patient sensitivity for metastases between standard and WB-MRI staging pathways against a consensus reference standard at 12 months, in the per-protocol population. Secondary outcomes were difference in per-patient specificity for metastatic disease detection between standard and WB-MRI staging pathways, differences in treatment decisions, staging efficiency (time taken, test number, and costs), and per-organ sensitivity and specificity for metastases and per-patient agreement for local T and N stage. This trial is registered with the International Standard Randomised Controlled Trial registry, number ISRCTN43958015, and is complete.

How to avoid describing your radiological research study incorrectly

“…"Diagnostic test pathway" designs are increasingly popular and, like diagnostic accuracy studies, participants receive both intervention and standard tests [20,21]. Results from the new test are revealed only when clinical decisions have been made and documented based on results from the standard test alone (i.e.…”

“…Results from the new test are revealed only when clinical decisions have been made and documented based on results from the standard test alone (i.e. reflecting standard clinical practice in the absence of the new test): By then revealing results from the new test, it is possible to determine how the new test impacts on patients' clinical trajectory [20]. More advanced designs compare multiple tests, with all evaluated against a reference.…”

Whole-body MRI compared with standard pathways for staging metastatic disease in lung and colorectal cancer: the Streamline diagnostic accuracy studies

“…Thereafter, radiologists with experience of < 100 WB-MRI data sets underwent a period of 'buddy' reporting with a more experienced radiologist (experience of > 100 WB-MRI data sets) and were only permitted to report alone once deemed competent by the more experienced radiologist. 25,26 This process was specifically designed to mirror how WB-MRI would be reported in standard NHS practice were it to become disseminated. We specifically avoided using a small number of highly experienced subspecialty radiologists who would not be representative of the NHS radiological workforce.…”

“…Reporting radiologists were instructed to interpret the WB-MRI as they would in their routine clinical practice, taking into account the known morphology and characteristics of potential metastatic disease across the various sequences. 22,25,26 Following completion of the CRF, the reporting radiologist produced a free-text clinical report as per their usual clinical practice (using all available sequences and based on the TNM 7th edition) 27 for subsequent release to the clinical team. This report contained information relating to the local T and N stage of the tumour, together with the presence, location, number and size of metastatic deposits as well as important 'incidental' findings, for example a second malignancy.…”

“…Multidisciplinary consensus panel review is the standard methodology for diagnostic test accuracy studies where an independent reference standard does not exist or is impossible because of incorporation bias. 23,25,26,28 The Streamline trials applied this methodology. Specifically, each recruitment site convened a series of consensus panels to derive the reference standard for the cancer TNM stage at recruitment for their participants.…”