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

Abstract

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...

Initial Staging of Locally Advanced Rectal Cancer and Regional Lymph Nodes

“…To the best of our knowledge, our study is the first that confirms an association between the tumor cellularity and the metabolic activity both in pathological lymph nodes and the related untreated LARC. 11 , 12 ADCmin and ADCmean did not, however, help differentiate pathological from benign lymph nodes.…”

“…However, we found a statistically significant negative correlation between ADCmean and the corresponding SUVmean values (ρ = −0.61, P = 0.0017) and between ADCmin and SUVmax (ρ = −0.66, P = 0.0005) values. Two previous studies 11 , 12 have shown a significant negative correlation between ADCmin and SUVmax ( r = −0.450, P = 0.009; and r = −0.347, P = 0.026, respectively) for primary rectal adenocarcinoma. In these studies, ADCmin was determined as the lowest value and SUVmax as the highest value among all voxels of the entire volume in each tumor.…”

“… 9 , 10 However, only a few studies have assessed this relation in locally advanced rectal cancer (LARC). 11 , 12 …”

Locally advanced rectal cancer: post-chemoradiotherapy ADC histogram analysis for predicting a complete response

“…Colakoglu et al (28) reported a significant negative correlation between minimum ADC and SUVmax in rectal cancer. In addition, a few previous studies have shown that minimum ADC in the tumor showed strong correlation with high cellularity (20,29).…”

Predictive Value of Diffusion, Glucose Metabolism Parameters of PET/MR in Patients With Head and Neck Squamous Cell Carcinoma Treated With Chemoradiotherapy

“…Several studies found negative associations between SUV max and ADC values ( 34 , 35 ). However, in our study, no significant linear correlations were found between the investigated parameters.…”