BackgroundFast 78‐second multicontrast echo‐planar MRI (EPIMix) has shown good diagnostic performance for detecting infarctions at a comprehensive stroke center, but its diagnostic performance has not been evaluated in a prospective study at a primary stroke center.PurposeTo prospectively determine whether EPIMix was noninferior in detecting ischemic lesions compared to routine clinical MRI.Study typeProspective cohort study.PopulationA total of 118 patients with acute MRI and symptoms of ischemic stroke.Field Strength and SequenceA 3 T. EPIMix (echo‐planar based: T1‐FLAIR, T2‐weighted, T2‐FLAIR, T2*, DWI) and routine clinical MRI sequences (T1‐weighted fast spin echo, T2‐weighted PROPELLER, T2‐weighted‐FLAIR fast spin echo, T2* gradient echo echo‐planar, and DWI spin echo echo‐planar).AssessmentThree radiologists, blinded for clinical information, assessed signs of ischemic lesions (DWI↑, ADC↓, and T2/T2‐FLAIR↑) on EPIMix and routine clinical MRI, with disagreements solved in consensus with a fourth reader to establish the reference standard.Statistical testsDiagnostic performance including sensitivity and specificity against the reference standard was evaluated. EPIMix sensitivity was tested for noninferiority compared to the reference standard using Nam's restricted maximum likelihood estimation (RMLE) Score. A P‐value < 0.05 was considered statistically significant.ResultsOf 118 patients (mean age 62 ± 16 years, 58% males), 25% (n = 30) had MRI signs of acute infarcts. EPIMix was noninferior with 97% (95% CI 83–100) sensitivity for reader 1, 100% (95% CI 88–100) sensitivity for reader 2, and 90% (95% CI 88–98) sensitivity for reader 3 vs. 93% (95% CI 78–99) sensitivity for readers 1 and 2 and 90% (95% CI 74–98) for reader 3 on routine clinical MRI. Specificity was 99% (95% CI 94–100) for reader 1, 100% (95% CI 96–100) for reader 2, and 98% (95% CI 92–100) for reader 3 on EPIMix vs. 100% (95% CI 96–100) for all readers on routine clinical MRI.ConclusionEPIMix was noninferior to routine clinical MRI for the diagnosis of acute ischemic stroke.Evidence Level2Technical EfficacyStage 2

Correct and timely diagnosis of pancreatic cancer (PC) is essential for treatment selection but is still clinically challenging. Standard-of-care imaging methods can sometimes not differentiate malignancies from inflammatory lesions or detect malignant transformation in premalignant lesions. This interim analysis of a prospective clinical trial aimed to evaluate the diagnostic accuracy of [ 68 Ga]fibroblast activation protein inhibitor (FAPI)-46 PET/CT for PC and determine the sample size needed to demonstrate whether this imaging technique improves the characterization of equivocal lesions detected by standard-of-care imaging methods. Methods: [ 68 Ga]FAPI-46 PET/CT imaging was performed on 30 patients scheduled for surgical resection of suspected PC. Target lesions were delineated, SUV max and SUV mean were determined, and the results were compared with those of standard-of-care imaging. Receiver operating characteristics were calculated for the whole cohort and a subcohort of 11 patients with an equivocal clinical imaging work-up preoperatively. Postoperative histopathologic findings served as a reference standard, and the statistical power was determined. Results: Histopathologic examination revealed malignancy in 20 patients and benign lesions in 10 patients. Significantly elevated [ 68 Ga]FAPI-46 uptake was observed in malignant tumors compared with benign lesions (P , 0.001). Receiver-operatingcharacteristic analyses established optimal cutoffs for both SUVs for differentiation of malignant from nonmalignant pancreatic tumors. The optimal SUV max cutoff was 10.2 and showed 95% sensitivity and 80% specificity for the whole cohort, as well as 100% diagnostic accuracy when considering the subcohort with equivocal imaging work-up only. For sufficient statistical power, 38 equivocal observations are needed. Conclusion: We conclude that [ 68 Ga]FAPI-46 PET/CT can accurately differentiate malignant from benign pancreatic lesions deemed equivocal by standard-of-care imaging. This trial will therefore continue to recruit a total of 120 patients to reach those 38 equivocal observations needed for sufficient statistical power. On the basis of our findings, we propose that [ 68 Ga]FAPI-46 PET/CT not only can be clinically applied as a complement but also could become a necessary tool when standard-of-care imaging is inconclusive.

After neoadjuvant chemotherapy, preoperative imaging with 68Ga-FAPI-46 PET/CT showed a similar level of tracer uptake at the location of the primary tumors in 2 patients with gastric cancer. Postoperative histopathology revealed residual malignant cells only in one of the patients, whereas the elevated FAPI uptake in the other patient correlated to an inflammatory reaction and fibrosis. With this case, we would like to highlight that an increased FAPI uptake in inflammatory and fibrotic tissue early after chemotherapy may represent a potential interpretation pitfall. Further studies evaluating the clinical application of FAPI-PET in assessing residual cancer tissue are warranted.