Value of diffusion-weighted imaging for the discrimination of pancreatic lesions: a meta-analysis

Diagnostic performance of diffusion MRI for pancreatic ductal adenocarcinoma characterisation: A meta-analysis

PURPOSE

To assess the diagnostic performance of intravoxel incoherent motion (IVIM) and diffusion-weighted imaging (DWI) for characterising pancreatic ductal adenocarcinoma (PDAC).

METHOD

A literature search was performed through PubMed, Web of Science, the Cochrane Library, and Embase databases. The search date was updated to extend until 28 October 2020, with no starting time limitation. The pooled sensitivity and specificity were calculated using a bivariate random effects model. Summary receiver operating characteristic curves were constructed, and area under the curve (AUC) of each diffusion parameter was calculated. Subgroup and meta-regression analyses were performed to assess for heterogeneity. Study quality was assessed.

RESULTS

Twenty-nine studies involving 1579 participants were included, of which 26 evaluated the apparent diffusion coefficient (ADC) and eight evaluated IVIM, with five evaluating both ADC and IVIM. Pooled sensitivity and specificity of ADC were 83 % (95 % CI, 76 %-88 %, I² = 86 %) and 85 % (95 % CI, 79 %-90 %, I² = 77 %), respectively, and AUC was 0.91 (95 % CI, 0.88-0.93). The perfusion fraction had the highest diagnostic accuracy in the IVIM model; the pooled sensitivity, specificity, and AUC were 87 % (95 % CI, 81 %-92 %, I² = 45 %), 88 % (95 % CI, 77 %-94 %, I² = 57 %), and 0.93 (95 % CI, 0.91-0.95), respectively. The pooled sensitivity, specificity and AUC for the tissue diffusion coefficient were 74 % (95 % CI, 55 %-87 %, I² = 87 %), 69 % (95 % CI, 52 %-82 %, I² = 73 %), and 0.77 (95 % CI, 0.73-0.81), respectively. And the pooled sensitivity, specificity, and AUC for the pseudodiffusion coefficient were 89 % (95 % CI, 77 %-96 %, I² = 79 %), 74 % (95 % CI, 60 %-84 %, I² = 78 %), and 0.88(95 %CI,0.85-0.91), respectively. Meta-regression analyses revealed that study design (specificity, P＜0.01), region-of-interest delineation (sensitivity, P = 0.02;specificity, P = 0.03), field strength (sensitivity, P＜0.01), and thickness (sensitivity, P＜0.01; specificity, P = 0.01) were sources of ADC heterogeneity.

CONCLUSIONS

DWI and IVIM have comparable diagnostic power and good diagnostic performance for characterising PDAC.

CT and MR features that can help to differentiate between focal chronic pancreatitis and pancreatic cancer

Diagnosis of a focal pancreatic mass in routine clinical practice can be a challenge because patients with chronic pancreatitis may present with symptoms and imaging findings that can be difficult to distinguish from pancreatic cancer. Markers, such as cancer antigen 19-9 and carcinoembryonic antigen, are helpful if abnormal, but normal values do not rule out pancreatic cancer. One of the strongest complicating factors is that chronic pancreatitis is a risk factor for pancreatic cancer. Transition of chronic pancreatitis to pancreatic cancer is relatively rare, but it normally has a poor prognosis because diagnosis is often delayed. From a radiologic diagnosis perspective, the classic so-called double-duct sign is helpful. This sign is considered a hallmark sign of pancreatic cancer on magnetic resonance cholangiopancreatography, but it can also be identified in patients with chronic pancreatitis or with other conditions. A number of additional imaging findings or signs are, therefore, necessary. The aim of this article was to describe the strong CT and MR imaging features or integrated imaging features that can help to differentiate between pancreatic cancer and focal chronic pancreatitis.

Meta-analysis of quantitative diffusion-weighted MR imaging in differentiating benign and malignant pancreatic masses

There have been numerous studies done to explore the diagnostic performance of quantitative diffusion-weighted (DW) MR imaging to differentiate between benign and malignant pancreatic masses. However, the results have been inconsistent. We performed a meta-analysis to investigate whether DW-MR imaging can differentiate between these two diseases. Databases including MEDLINE, EMBASE and Cochrane Library were utilized to find relevant articles published between January 2001 and January 2014. A Stata version 12.0 and a Meta-Disc version 1.4 were used to describe primary results. Twelve studies with 594 patients, which fulfilled the inclusion criteria, were enrolled for the analysis. The pooled sensitivity and specificity of DW imaging was 0.91 (95% CI: 0.84, 0.95) and 0.86 (95% CI: 0.76, 0.93) respectively. The area under the curve of the summary receiver operating characteristic was 0.95 (95% CI: 0.93, 0.96). The results indicated that DW imaging might be a valuable tool for differentiating benign and malignant pancreatic masses.

Endoplasmic reticulum stress does not contribute to steatohepatitis in obese and insulin-resistant high-fat-diet-fed foz/foz mice

Unlike in mice developing simple steatosis, endoplasmic reticulum stress does not contribute to the pathogenesis of insulin resistance and steatohepatitis in high-fat-diet-fed foz/foz mice, which develop progressive liver disease in the metabolic context seen in human non-alcoholic steatohepatitis.

Importance of b value in diffusion weighted imaging for the diagnosis of pancreatic cancer

AIM

To investigate the use of multi-b-value diffusion-weighted imaging in diagnosing pancreatic cancer.

METHODS

We retrospectively analyzed 33 cases of pancreatic cancer and 12 cases of benign pancreatic tumors at the Second Affiliated Hospital of Kunming Medical University from December 2008 to January 2011. The demographic characteristics, clinical presentation, routine magnetic resonance imaging and diffusion weighted imaging (DWI) features with different b values were reviewed. Continuous data were expressed as mean ± SD. Comparisons between pancreatic cancer and benign pancreatic tumors were performed using the Student's t test. A probability of P < 0.05 was considered statistically significant.

RESULTS

Thirty-three patients with pancreatic cancer were identified. The mean age at diagnosis was 60 ± 5.6 years. The male: female ratio was 21:12. Twenty cases were confirmed by surgical resection and 13 by biopsy of metastases. T1 weighted images demonstrated a pancreatic head mass in 16 patients, a pancreatic body mass in 10 cases, and a pancreatic tail mass with pancreatic atrophy in 7 cases. Eight patients had hepatic metastases, 13 had invasion or envelopment of mesenteric vessels, 4 had bone metastases, and 8 had lymph node metastases. DWI demonstrated an irregular intense mass with unclear margins. Necrotic tissue demonstrated an uneven low signal. A b of 1100 s/mm² was associated with a high intensity signal with poor anatomical delineation. A b of 700 s/mm² was associated with apparent diffusion coefficients (ADCs) that were useful in distinguishing benign and malignant pancreatic tumors (P < 0.05). b values of 50, 350, 400, 450 and 1100 s/mm² were associated with ADCs that did not differentiate the two tumors.

CONCLUSION

Low b value images demonstrated superior anatomical details when compared to high b value images. Tumor tissue definition was high and contrast with the surrounding tissues was good. DWI was useful in diagnosing pancreatic cancer.