Diffusion-Weighted Imaging of the Rectosigmoid Colon

Kılıçkesmez, Özgür; Atilla, Serhan; Soylu, Aliye; Taşdelen, Neslihan; Bayramoğlu, Sibel; Cimilli, Tan; Gurmen, Nevzat

doi:10.1097/rct.0b013e31819a60f3

Cited by 43 publications

(23 citation statements)

References 21 publications

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“…A difference from previous study comes from the inclusion of longer intestinal segments to be assessed. However, the results of the study are similar to those of the earlier study (6) in that they call for further research and requirement of increasing patient population size. Actually, this conclusion is justified because of the overlapping ADC values.…”

supporting

confidence: 79%

“…It has been known previously that a number of benign lesions can exhibit hyperintensity on DW-MRI with high b-values, (9) and that ADC values in benign and malignant lesions may overlap, which makes it difficult to distinguish lesions using DW-MRI alone. In both studies (2,6), it was emphasized that, radiologists should be aware of possible overlaps of ADC values that may lead to misdiagnoses when only DWI is interpreted.…”

mentioning

confidence: 99%

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Are we expecting too much from the diffusion-weighted MRI?

Erden¹

2013

Turk J Gastroenterol

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Diffusion-weighted magnetic resonance imaging (DW-MRI) is a method where the signal required to produce a MRI image is determined by the "mobility of water". Diffusivity measurements have multiple components related to tissue cellularity and organization, integrity of the cell membranes, extracellular space tortuosity and perfusion (1).Until recent years, main limitation for the use of DWI in the body area wa the artefacts originating from the physiologic movements which decrease the diagnostic yield of the method. With advanced technology, elimination of disturbing artifacts can be possible to a degree… Diffusion-weighted imaging signal intensity and the values of apparent diffusion coefficient (ADC) are of particular interest, because these parameters can sometimes show changes in bowel wall, when no abnormalities are typically seen on conventional MR images. Therefore, this method is rapidly becoming an adjunct to a conventional body MRI study, especially in the early detection of cancer. The ADC map provides quantitative information on diffusion. It is a measure of the freedom of water diffusion and is useful in tissue characterization. Malign lesions are characterized by a high signal on DWI and a low signal on ADC. Measured values from ADC map are believed to be low because of a shift (diffusion) of water within malign tissue, from the extracellular to the intracellular compartment, is relatively restricted. Thus, one of the important advantages of the DWI is that it can manifest the nature of the lesion without the need for intravenous contrast material injection. This is particularly beneficial in patients with reduced renal function (1).In the current issue of Turkish Journal of Gastroenterology, Solak and colleagues (2) have investigated the value of DW-MRI in the differentiation of benign and malignant diffuse bowel wall thickening. They discussed the diagnostic importance and potential use of ADC measurements. For quantitative analysis in DW-MRI, a radiologist has measured the thickened colonic wall ADC values in the three regions of interest (ROI) by using dedicated software at the workstation. A circular ROI with a diameter of at least 4 mm2 has been placed to three different portions of the thickened wall to obtain average ADC values of the lesion. The authors concluded that benign bowel pathologies leading to wall thickening had significantly higher ADC values than those of malignant ones. In ROC curve analysis, the cut-off value of ADC to differentiate benign from malignant wall thickening was found as 1.21mm 2 /s with a sensitivity of 100%, a specificity of 87,3%, and an accuracy of 89,3%. With visual assessment of the DWIs and the measurements of ADC values, malignant lesions were differentiated from benign ones with sensitivity of 100%, specificity of 89,2%, and an accuracy of 90,4%.Before considering whether this bald conclusion does justice to the possible contribution of DWI to the noninvasive differentiation of benign and malign bowel lesions, it is worth considering that, even in the abs...

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supporting

confidence: 79%

mentioning

confidence: 99%

Are we expecting too much from the diffusion-weighted MRI?

Erden¹

2013

Turk J Gastroenterol

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“…In a small retrospective series, ADC values of the normal rectum and rectosigmoid malignancy groups and rectosigmoid carcinoma and inflammatory bowel disease groups were significantly different (P < 0.01). A cut-off value for carcinomas of 1.14×10 -3 mm 2 /s yielded a sensitivity and specificity of 93.3% and 93.3%, respectively (26). In a recent study, Song et al (23) reported that the mean ADC of the viable tumor group was significantly lower than that of the non-viable tumor group.…”

Section: Discussionmentioning

confidence: 99%

Can diffusion-weighted MRI determine complete responders after neoadjuvant chemoradiation for locally advanced rectal cancer?

Engin

Sharifov²,

Güral³

et al. 2012

Diagn Interv Radiol

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N eoadjuvant chemoradiotheraphy (CRT) improves tumor downstaging, pathological complete response (pCR), and local control (1, 2). pCR rates of 13%-30% have been reported in phase II and phase III trials following 5-fluorouracil-based preoperative CRT (3, 4). Currently, management of patients with clinical complete response (cCR) remains controversial (5-8).A recent meta-analysis including 218 phase I/II or retrospective studies and 28 phase III trials of adjuvant CRT reported that T3 rectal cancer is associated with high local recurrence rates after nonsurgical treatment (9). In addition, similiar results were recently shown from a study using a "wait-and-see" policy after CRT (10).Accurate imaging methods are needed to evaluate CRT responses, and post-CRT magnetic resonance imaging (MRI) is frequently used for this purpose. However, the method has low accuracy in predicting the pathological stage of the tumor and can often overstage T1 and T2 tumors due to the limited capability of MRI to differentiate viable tumor, residual fibrotic nontumoral tissue, and a desmoplastic reaction. Understaging of irradiated rectal cancer can affect treatment planning, including the surgical strategy, and thus affects the tumor recurrence rate and prognosis (11).Diffusion-weighted (DW)-MRI is a functional imaging technique that yields qualitative and quantitative information and provides unique insights regarding tumor cellularity, integrity of cell membranes, and microcirculation.

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“…In rectal cancer, the applications of DWI include tumor detection, tumor characterization, distinguishing tumor tissue from nontumor tissue, and monitoring and predicting treatment response (3)(4)(5)(6)(7)(8). For local staging of rectal cancer, adding DWI to conventional magnetic resonance imaging (MRI) yields better identification of tumor borders and locoregional lymph nodes than conventional MRI alone (9,10).…”

mentioning

confidence: 99%

Correlation of minimum apparent diffusion coefficient with maximum standardized uptake on fluorodeoxyglucose PET-CT in patients with rectal adenocarcinoma

Erden²,

No³

et al. 2013

Diagn Interv Radiol

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ABDOMINAL IMAGINGORIGINAL ARTICLE PURPOSE The aim of this study was to retrospectively assess the correlation between minimum apparent diffusion coefficient (ADC min ) values obtained from diffusion-weighted magnetic resonance imaging (MRI) and maximum standardized uptake values (SUV max ) obtained from positron emission tomography-computed tomography (PET-CT) in rectal cancer. MATERIALS AND METHODSForty-one patients with pathologically confirmed rectal adenocarcinoma were included in this study. For preoperative staging, PET-CT and pelvic MRI with diffusion-weighted imaging were performed within one week (mean time interval, 3±1 day). For ADC measurements, the region of interest (ROI) was manually drawn along the border of each hyperintense tumor on b=1000 s/mm 2 images. After repeating this procedure on each consecutive tumor-containing slice to cover the entire tumoral area, ROIs were copied to ADC maps. ADC min was determined as the lowest ADC value among all ROIs in each tumor. For SUV max measurements, whole-body images were assessed visually on transaxial, sagittal, and coronal images. ROIs were determined from the lesions observed on each slice, and SUV max values were calculated automatically. The mean values of ADC min and SUV max were compared using Spearman's test. RESULTSThe mean ADC min was 0.62±0.19×10 -3 mm 2 /s (range, 0.368-1.227×10 -3 mm 2 /s), the mean SUV max was 20.07±9.3 (range, 4.3-49.5). A significant negative correlation was found between ADC min and SUV max (r=-0.347; P = 0.026). CONCLUSIONThere was a significant negative correlation between the ADC min and SUV max values in rectal adenocarcinomas. D iffusion-weighted imaging (DWI) is a widely used technique for disease evaluation in oncology (1, 2). In rectal cancer, the applications of DWI include tumor detection, tumor characterization, distinguishing tumor tissue from nontumor tissue, and monitoring and predicting treatment response (3-8). For local staging of rectal cancer, adding DWI to conventional magnetic resonance imaging (MRI) yields better identification of tumor borders and locoregional lymph nodes than conventional MRI alone (9, 10).The apparent diffusion coefficient (ADC) map obtained from DWI shows the freedom of water diffusion, and values calculated on the map are useful parameters in tissue characterization. By performing diffusion-weighted (DW) MRI with at least two diffusion weightings, or b values, the differential signal attenuation at different b values can be used to calculate the ADC (2). Regardless of the tumor type and location, the ADC values reflect tumor morphology, including the cellular density, integrity of cell membrane, and nuclear-to-cytoplasm ratio (11,12).Positron emission tomography/computed tomography (PET-CT) has become a crucial method in cancer imaging, both for diagnosis and staging, as well as for offering prognostic information based on tumor response. In PET-CT, the standardized uptake value (SUV) is a measure of fluorodeoxyglucose (FDG) uptake, which has been shown to be helpful in estab...

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Diffusion-Weighted Imaging of the Rectosigmoid Colon

Cited by 43 publications

References 21 publications

Are we expecting too much from the diffusion-weighted MRI?

Are we expecting too much from the diffusion-weighted MRI?

Can diffusion-weighted MRI determine complete responders after neoadjuvant chemoradiation for locally advanced rectal cancer?

Correlation of minimum apparent diffusion coefficient with maximum standardized uptake on fluorodeoxyglucose PET-CT in patients with rectal adenocarcinoma

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