Value of diffusion-weighted MR imaging performed with quantitative apparent diffusion coefficient values for cervical lymphadenopathy. Diffusion-weighted whole-body MR imaging with background body signal suppression: a feasibility study at 3. Diagnostic value of whole-body diffusion-weighted magnetic resonance imaging for detection of primary and metastatic malignancies: a meta-analysis. Evaluation of dual-source parallel RF excitation for diffusion-weighted whole-body MR imaging with background body signal suppression at 3.
References Publications referenced by this paper. Clinical applications of PET in oncology.
Diffusion-Weighted MR Imaging : Applications in the Body
Eric Rohren , Timothy G. Turkington , Robert E. Diffusion-weighted imaging: basic concepts and application in cerebral stroke and head trauma Thierry A. Sensitivity encoding for fast MR imaging of the brain in patients with stroke. Sensitivity-encoded diffusion tensor MR imaging of the cervical cord. Mara Cercignani , Mark A. Horsfield , Federica Agosta , Massimo Filippi. Differentiation of clinically benign and malignant breast lesions using diffusion-weighted imaging.
DTI can be used to monitor the myelination process during the different phases of development in fetuses, infants and childhood[ 20 , 21 ]. Similarly DTI can also be used to characterize white matter disorders and grey matter migration disorders in children[ 22 , 23 ]. Diffusion-weighted imaging has got immense potential in the field of onco-imaging. It is easy to implement and adds very little time to a standard MR examination.
Malignant lesions have lower ADC values compared to surrounding normal tissue, edema and benign tumors in brain, head and neck malignancies, prostate and liver cancer[ 24 ]. Malignant tumors differ in their cellularity and biologic aggressiveness, which can be quantified in terms of ADC values[ 24 , 25 ]. Whole-body DWI, i. Imaging is performed at multiple stations and then post-processed to form a composite image of the whole body. The images are displayed as maximum intensity projections with a reversed gray scale[ 26 ]. Signals from majority of normal tissue are suppressed with some exceptions such as the prostate, spleen, ovaries, testes, spinal cord and endometrium.
Areas showing restricted diffusion such as highly cellular lymph nodes are strikingly highlighted. Small foci of tumors within the abdomen or peritoneum may also get highlighted by using this technique[ 26 , 27 ]. Recent applications of DWI in oncology include evaluation of response to chemoradiotherapy. Increase in ADC value can be detected before the size of the tumor decreases[ 28 , 29 ]. There is a significant difference in ADC values of carcinomas, lymphomas, benign salivary gland tumors and benign cysts.
Image acquisition and interpretation
Wang et al[ 30 ] reported that ADC less than 1. DWI helps in the differentiation of benign from malignant tumors, lymphoma from squamous cell cancer, and benign from metastatic lymphadenopathy. It also helps in differentiation of necrotic tumors from abscesses and selection of appropriate site for biopsy.
ADC value of necrosis is especially helpful in discriminating metastasis from lymphadenitis. Kato et al[ 31 ] reported significantly lower ADC value in suppurative lymphadenitis 0.
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In another study Zhang et al[ 32 ] reported additional value of ADC measurements in necrotic and solid portions. ADC calculations are also useful in monitoring the patient after chemo-radiotherapy and differentiation of recurrent tumors from post-treatment changes[ 28 , 29 , 33 , 34 ]. Axial b0 A , b B and apparent diffusion coefficient map are showing multiple enlarged neck nodes. Nodes are showing slightly hyperintense signal on b0 images and retaining their signal on b image with low signal on corresponding ADC C.
ADC: Apparent diffusion coefficient. In a recent meta-analysis by Shen et al[ 35 ] reported that malignant pulmonary lesions have significantly lower ADC values than benign lesions [1. Wang et al[ 41 ] have reported that compared to DCE-MRI used alone this strategy significantly improves the diagnostic performance of MRI for differential diagnosis between ductal carcinoma in situ DCIS and invasive breast cancer[ 42 ].
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The sensitivity of the DTI parameters to detect breast cancer was found to be high, particularly in dense breasts. Carcinoma breast. Axial T2W fat saturated image A is showing a heterogeneously hyperintense mass lesion in right breast. Mass is showing hyperintense signal on b image B , with low signal on apparent diffusion coefficient map C ; dynamic post-contrast MIP image D is showing contrast enhancement within the mass with type 3 enhancement curve E.
Clinical applications of DW MRI include treatment response monitoring and prognostication in patients receiving systemic and focal ablative therapies for hepatic and pancreatic malignancies[ 43 - 46 ]. Hardie et al[ 47 ] compared the utility of DWI in detection of liver metastases.
They reported that DWI has DW MR imaging has been investigated in diffuse hepatic parenchymal disease such as non-alcoholic fatty liver disease and hepatic fibrosis. However its clinical applicability is questionable as it suffers from multiple confounders making quantifying liver fibrosis through ADC difficult[ 48 ].
In a recent meta-analysis, Hong et al[ 48 ] reported that DWI has a sensitivity and specificity of 0. In another meta-analysis, Niu et al[ 49 ] reported pooled sensitivity of 0.
For most abdominal applications b -values of 0, and are standard except for prostate imaging where use of values up-to b is considered more suitable. Hepatocellular carcinoma in cirrhotic liver. Axial T2W image is showing a hyperintense lesion in segment 5 of liver A ; lesion is enhancing in arterial phase B ; and it shows hyperintense signal on b image C and hypointense on apparent diffusion coefficient map D.
Liver metastases. Patient with gall bladder carcinoma is showing a large T2 hyperintense mass in gall bladder fossa A showing restricted diffusion on b image B ; there are multiple metastatic lesions in liver in segments 2, 3 and 4. These lesions are also showing restricted diffusion. Another important point is the fact that a b image D is showing more lesion compared to a corresponding b0 image C.
Carcinoma gall bladder. Axial T2W image showing a large heterogeneously hyperintense mass in gall bladder fossa of liver.
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It is showing hyperintense signal on b image B and are showing peripheral hyperintense signal on apparent diffusion coefficient map C ; coronal projectional MRCP image is showing biliary obstruction with involvement of primary and right secondary biliary confluence. Pancreatic adenocarcinoma.
Axial CECT images showing a hypo-enhancing mass in the neck and head region of pancreas A with a dilated pancreatic duct B ; multiple hypodense lesions can be noted within the liver parenchyma. Mass in the neck and head region of pancreas is showing hyperintense signal on b image and so are the focal liver lesions C ; corresponding apparent diffusion coefficient map shows hypointense signal within the mass D. DWI is useful for detection of colorectal cancer, nodal and hepatic metastases and prediction of response after radio-chemotherapy for locally advanced rectal cancer[ 50 - 52 ].
DWI detects therapy-induced modifications in lesion vascularity during anti-angiogenic therapy before significant changes in size are evident[ 53 , 54 ]. DWIBS has been reported a useful tool in detection of nodal metastasis of colorectal cancer[ 55 ].
Imaging in Medicine
In addition to its utility in abdominal malignancies, DWI has also been found useful in inflammatory bowel disease. It has also been found to be useful in detection and characterization of extraintestinal manifestations and complications[ 57 ]. There have been attempts to distinguish various histological subtypes, but due to overlap in the ADC values such predictions have been found to be difficult[ 59 - 61 ].
In patients with transitional cell cancer, histological grade is the most important factor determining biological aggressiveness. Renal cell carcinoma vs simple cyst. Axial contrast-enhanced magnetic resonance image shows non-enhancing bosniak category I cyst in right kidney arrowhead and Bosniak category IV cyst enhancing mural nodules in left kidney arrow.
Latter was found to be clear cell renal cell carcinoma. Renal cell carcinoma with malignant inferior vena cava thrombus. Apparent diffusion coefficient maps A and B of a patient with large left renal mass with contiguous extension into renal vein arrows and inferior vena cava arrowhead malignant thrombosis.
Both the renal mass and intravascular thrombus had similar apparent diffusion coefficient values.
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