MR Imaging of the Pancreas

CT and MR imaging patterns for pancreatic carcinoma invading the extrapancreatic neural plexus (Part II): Imaging of pancreatic carcinoma nerve invasion

“…The signal intensity of the nerve invasion is similar to that of pancreatic carcinoma on �R imaging [17,18] , mostly showing hypointensity on T1-weighted, isointensity or a little hyperintensity on T2-weighted, hypointensity on arterial phase, and isointensity on delayed phase images after Gd-DTPA contrast enhancement [31,34,35] . We have previously studied 20 patients with pancreatic carcinoma by �R imaging, and found the signs of extrapancreatic neural plexus invasion in 16 of the 20 patients (80%); 50% of patients showed streaky and strandlike signal intensity structures in fatty tissue, and 30% showed masses near the tumor.…”

“…�agnetic resonance imaging (�RI) is a valuable tool in the assessment of the full spectrum of pancreatic diseases, including effective detection, diagnosis, and evaluation of the stage of pancreatic carcinoma [17] . The sequences including coronal and axial single shot fast spin-echo (��F�E) T2-weighted �R images, spoiled gradient-echo (�PGR) T1-weighted in-and out-of-phase �R images; as well as fat saturation three-dimensional enhanced �PGR dynamic �R images, axial fat-saturated fast recovery fast spin-echo (FRF�E) T2-weighted images, etc., are used routinely in the diagnosis of pancreatic carcinoma invasion.…”

“…On �R imaging, the degree of the extrapancreatic neural invasion might be classified into three grades [8,17] : NV0, no change in fat signal intensity; NV1, streaky and strand-like signal intensity structure in fat tissue ( Figure 7); NV2, irregular masses (diameter larger than 10 mm) adjacent to the lesions (Figure 8). …”

The Role of Diffusion Weighted MR Imaging in the Diagnosis of Acute Pancreatitis

“…DWI is influenced by both water diffusion and T2 relaxation time(T2-shinethrough effect) which is the non-pure ADC maps of DW images, containing mixed contributions from T2 effects and spin-density phenomenon, leading to high signal appearing simple cysts on DWI with b value 0 sec/mm 2 , low signal intensity on high-b value images and high signal intensity on ADC maps, but however hyper intensity of abscesses, hydatid cysts and neoplastic cysts on 1000 sec/mm images with adequate SNR so multiple excitations with applied three dimensional gradients allow accurate images with good SNR for multiplanar reconstruction Koh et al, 2007, Aydin, 2012cIchikawa et al, 2007;Le Bihan et al, 1988;Takahara et al, 2004). Conventional pancreatic MR imaging is more widely used in the diagnosis of cystic and solid pancreatic neoplasms due to its high soft-tissue resolution, T1 weighted (T1W) gradient echo-T2 weighted (T2W) single-shot turbo spin echo fat suppressed images and dynamic contrast-enhanced T1W gradient-echo with fat saturation are involved on conventional MR imaging (Wang et al, 2011;Takahara et al, 2004;Pamuklar et al, 2005). In addition, heavily T2W coronal and oblique MRCP sequence can be used to detect pancreatic ductal system and relation of pancreatic masses to the pancreatic major and minor ducts (Prasad et al, 2001;Makary et al, 2005;Wang et al, 2011).…”

“…DWI may also show limited help in the differentiation of Acute Peripancreatic Fluid Collections (APFC) from Acute Necrotic Collections (ANC) due to acute hemorrhagic pancreatitis, predict variable ADC values on those circumstances due to nature of collections (Hemorrhage or necrosis), acute or chronic inflammatory edema. For distinguishing APFC from ANC, Contrast-enhanced CT is the standard gold reference (Wang et al, 2009;Carroll et al, 2007;Wada et al, 2010;Triester et al, 2002;Chatzicostas et al, 2003;Leung et al, 2005;Chatzicostas et al, 2002;Wiggermann et al, 2012;Pamuklar et al, 2005;Sica et al, 2002). In the differentiation of Pancreatic Pseudocyst (PP) and Walled of Necrosis (WON) due to pancreatitis, DWI may supply important information as ADC values are extremely higher in PP than in WON, restricted diffusion and low ADC values are quite common in WON than in PP so DWI can be easily be performed in the routine practice instead of CT, nevertheless both PP and WON may reveal confusing enhancements which may acquire mis and/or over diagnosis (Thomas et al, 2012;Shinya et al, 2008;Shinya et al, 2009;Wang et al, 2009;Wada et al, 2009;Matos et al, 2002;Inan et al, 2008;Akisik et al, 2009;Fattahi et al, 2009).…”