The role of proton MR spectroscopy and apparent diffusion coefficient values in the diagnosis of malignant thyroid nodules: preliminary results

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

“…Diffusion measurement is eventually sum of vectoral quantities, 3 orthogonal diffusion vector gradients; G X , G y , G z are used for calculation of ADC, sum of the square root of these vector magnitudes is the real ADC value and mostly favorable in isotropic diffusion Yoshikawa et al, 2006). Free or isotropic diffusion occurs when movement of water molecules is completely random and restricted, anisotropic diffusion occurs when the motion of water is restricted due to the barriers within cell membranes and macromolecules, signal measured from MRI can be sensitized to water diffusion by addition of balanced diffusion-sensitive, magnetic field gradients and this diffusionsensitizing gradients which acquire MR signals, are the real good contrast DW images because of the diffusion of water protons Aydin et al, 2012a;Koh et al, 2007;Le Bihan et al, 1988). The MR signal obtained by diffusion-sensitizing gradients are equated by: S (b) = So -(bxADC) , S (b) is the measured diffusion signal, So is the signal intensity without diffusion, b is the b-value (sec/mm 2 ) for determining the magnitude, duration and time between the pair of gradients and ADC of water molecules Aydin et al, 2012a;Koh et al, 2007).…”

“…In general, Rapidly growing tumors are characterized by increased tissue cellularity and cellular density with the increased amount of diffusion barriers, the motion of diffusion capacity is restricted and water diffuses from extracellular components to the intracellular space, resulting to low ADC values and high signal intensity on DWI, however high ADC values are attributed to the free motion of water molecules in fluid-rich biologic environments (Thomas et al, 2012;Shinya et al, 2009;Aydin et al, 2012a;Aydin et al, 2012b;Wang et al, 2011;Takeuchi et al, 2008;Ichikawa et al, 2007). 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).…”

“…Structural changes in benign or malignant tissues, may result in different signals on DWI which may be quantified by calculating the ADC values which is an objective parameter that reflects the quantitative expressions of the tissuespecific diffusions, that are related to the proportion of extracellular and intracellular components (Thomas et al, 2012;Shinya et al, 2008;Shinya et al, 2009;Balci et al, 2009;Aydin et al, 2012a;Aydin et al, 2012b;Koh et al, 2007;Wang et al, 2011;Takeuchi et al, 2008).…”

“…DWI is a new promising, non-invasive imaging technique that is being used increasingly in body applications, based on the random translational motion of water protons, indirectly proportional to the diffusion barriers, generating apparent diffusion coefficient (ADC), a net motion of water molecules (Thomas et al, 2012;Shinya et al, 2008;Shinya et al, 2009;Balci et al, 2009;Aydin et al, 2012a;Aydin et al, 2012b;Koh et al, 2007;Wang et al, 2011;Takeuchi et al, 2008;Ichikawa et al, 2007). Structural changes in benign or malignant tissues, may result in different signals on DWI which may be quantified by calculating the ADC values which is an objective parameter that reflects the quantitative expressions of the tissuespecific diffusions, that are related to the proportion of extracellular and intracellular components (Thomas et al, 2012;Shinya et al, 2008;Shinya et al, 2009;Balci et al, 2009;Aydin et al, 2012a;Aydin et al, 2012b;Koh et al, 2007;Wang et al, 2011;Takeuchi et al, 2008).…”

“…DWI has been recently applied in the evaluation of AP due to the latest soft and hardware advances in MR technology, DWI assesses the Brownian motion of free water within intra and extracellular spaces, is initially used in the detection of acute cerebral stroke then has become available for the detection of abdominal and pelvic tumors especially the renal and prostate tumors, focal hepatic lesions, thyroid nodules, meniscal tears, soft tissue pathologies, bone marrow edema etc. (Thomas et al, 2012;Shinya et al, 2008;Balci et al, 2009;Aydin et al, 2012a;Aydin et al, 2012b;Koh et al, 2007;Aydin, 2012c;Aydin et al, 2012d;Zhang et al, 2012;Daggulli et al, 2011;Onur et al, 2012;Aydin et al, 2011). In this review, we will discuss the utility and contribution of DWI in the accurate diagnosis of AP.…”