High signal intensity on diffusion-weighted magnetic resonance images is a useful finding for detecting early-stage pancreatic cancer

Association of pancreatic atrophy patterns with intraductal extension of early pancreatic ductal adenocarcinoma: a multicenter retrospective study

BACKGROUND

Focal pancreatic parenchymal atrophy (FPPA) and upstream pancreatic atrophy (UPA) may indicate the presence of early pancreatic cancer. In early pancreatic cancer, the tumor occasionally spreads laterally along the main pancreatic duct, presenting challenges in determining the extent of surgical resection. This study aimed to investigate the association of pancreatic atrophy pattern and intraductal cancer extension.

METHODS

Thirty-two patients with early-stage pancreatic cancer who underwent surgery at five participating centers were enrolled. Pancreatic atrophy was defined as the narrowing of parenchyma compared to the surrounding parenchyma and was classified as either FPPA (partial atrophy surrounding the pancreatic duct stenosis) or UPA (global atrophy caudal to the site of duct stenosis). Intraductal cancer extension was defined as an extension exceeding 10 mm.

RESULTS

Preoperative computed tomography revealed FPPA, UPA, and no parenchymal atrophy in 13, 13, and 6 patients. Cases with FPPA or UPA showed significantly longer cancer extensions than those without atrophy (P = 0.005 and P = 0.03, respectively). Intraductal cancer extension was present in all but one case of FPPA. 69% (9/13) of the cases with UPA showed intraductal cancer extension, whereas cases without atrophy showed no intraductal cancer extension. Importantly, two patients with FPPA or UPA showed positive resection margins during surgery and three patients with FPPA or UPA showed recurrence in the remnant pancreas.

CONCLUSIONS

The presence of FPPA and UPA indicates lateral cancer extension in early-stage pancreatic cancer. Preoperative assessment of the pancreatic parenchyma may provide valuable insights for determining the extent of surgical resection.

Diagnostic accuracy of apparent diffusion coefficient to differentiate intrapancreatic accessory spleen from pancreatic neuroendocrine tumors

BACKGROUND

Intrapancreatic accessory spleen (IPAS) shares similar imaging findings with hypervascular pancreatic neuroendocrine tumors (PNETs), which may lead to unnecessary surgery.

AIM

To investigate and compare the diagnostic performance of absolute apparent diffusion coefficient (ADC) and normalized ADC (lesion-to-spleen ADC ratios) in the differential diagnosis of IPAS from PNETs.

METHODS

A retrospective study consisting of 29 patients (16 PNET patients vs 13 IPAS patients) who underwent preoperative contrast-enhanced magnetic resonance imaging together with diffusion-weighted imaging/ADC maps between January 2017 and July 2020 was performed. Two independent reviewers measured ADC on all lesions and spleens, and normalized ADC was calculated for further analysis. The receiver operating characteristics analysis was carried out for evaluating the diagnostic performance of both absolute ADC and normalized ADC values in the differential diagnosis between IPAS and PNETs by clarifying sensitivity, specificity, and accuracy. Inter-reader reliability for the two methods was evaluated.

RESULTS

IPAS had a significantly lower absolute ADC (0.931 ± 0.773 × 10-3 mm2/s vs 1.254 ± 0.219 × 10-3 mm2/s) and normalized ADC value (1.154 ± 0.167 vs 1.591 ± 0.364) compared to PNET. A cutoff value of 1.046 × 10-3 mm2/s for absolute ADC was associated with 81.25% sensitivity, 100% specificity, and 89.66% accuracy with an area under the curve of 0.94 (95% confidence interval: 0.8536-1.000) for the differential diagnosis of IPAS from PNET. Similarly, a cutoff value of 1.342 for normalized ADC was associated with 81.25% sensitivity, 92.31% specificity, and 86.21% accuracy with an area under the curve of 0.91 (95% confidence interval: 0.8080-1.000) for the differential diagnosis of IPAS from PNET. Both methods showed excellent inter-reader reliability with intraclass correlation coefficients for absolute ADC and ADC ratio being 0.968 and 0.976, respectively.

CONCLUSION

Both absolute ADC and normalized ADC values can facilitate the differentiation between IPAS and PNET.

Abnormal Findings on "T1WI or DWI or MRCP:" An Effective Boolean Interpretation Model in Discriminating Small Pancreatic Ductal Adenocarcinoma from Control Group

Objectives

The objectives of the study was to evaluate the diagnostic performance of findings on T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI), and magnetic resonance cholangiopancreatography (MRCP) separately and to identify an optimal Boolean interpretation model for discriminating patients with small pancreatic ductal adenocarcinoma (PDAC) from control groups in clinical practice.

Material and Methods

We retrospectively enrolled 30 patients with surgery confirmed small PDAC (≤20 mm) and 302 patients without pancreatic abnormality between April 2008 and February 2020. The presence of masses was evaluated by T1WI, T2WI, and DWI. Abnormality of the main pancreatic duct (MPD) was evaluated by T2WI and MRCP. Multivariate logistic regression analysis was performed to select significant sequences for discriminating the small PDAC and control groups. Boolean operators "OR" or "AND" were used to construct sequence combinations. Diagnostic performances of these sequences and combinations were evaluated by X ² tests.

Results

The sensitivity of T2WI was lowest (20%) for detecting masses. For evaluating MPD abnormality, sensitivity was higher for MRCP than for T2WI (86.7% vs. 53.3%). Multivariate logistic regression analysis showed that T1WI and DWI for detecting the presence of masses and MRCP for evaluating MPD abnormality were significantly associated with differentiation between the two groups (P = 0.0002, P = 0.0484, and P < 0.0001, respectively). Seven combinations were constructed with T1WI, DWI, and MRCP. The combination of findings on "T1WI or DWI or MRCP" achieved the highest sensitivity of 96.7% and negative predictive value of 99.6%.

Conclusion

The combination of findings on "T1WI or DWI or MRCP" might be an optimal interpretation model for discriminating small PDAC from control groups in clinical practice.