Correlation of standardized uptake value and apparent diffusion coefficient in integrated whole-body PET/MRI of primary and recurrent cervical cancer

Abstract

Background: To evaluate a potential correlation of the maximum standard uptake value (SUVmax) and the minimum apparent diffusion coefficient (ADCmin) in primary and recurrent cervical cancer based on integrated PET/MRI examinations.

Methods: 19 consecutive patients (mean age 51.6 years; range 30-72 years) with histopathologically confirmed primary cervical cancer (n = 9) or suspected tumor recurrence (n = 10) were prospectively enrolled for an integrated PET/MRI examination. Two radiologists performed a consensus reading in random order, using a dedicated post-processing software. Polygonal regions of interest (ROI) covering the entire tumor lesions were drawn into PET/MR images to assess SUVmax and into ADC parameter maps to determine ADCmin values. Pearson's correlation coefficients were calculated to assess a potential correlation between the mean values of ADCmin and SUVmax.

Results: In 15 out of 19 patients cervical cancer lesions (n = 12) or lymph node metastases (n = 42) were detected. Mean SUVmax (12.5 ± 6.5) and ADCmin (644.5 ± 179.7 × 10(-5) mm2/s) values for all assessed tumor lesions showed a significant but weak inverse correlation (R = -0.342, p < 0.05). When subdivided in primary and recurrent tumors, primary tumors and associated primary lymph node metastases revealed a significant and strong inverse correlation between SUVmax and ADCmin (R = -0.692, p < 0.001), whereas recurrent cancer lesions did not show a significant correlation.

Conclusions: These initial results of this emerging hybrid imaging technique demonstrate the high diagnostic potential of simultaneous PET/MR imaging for the assessment of functional biomarkers, revealing a significant and strong correlation of tumor metabolism and higher cellularity in cervical cancer lesions.

Figure 1. Figure a shows a T1w 3D VIBE image of an inhomogeneously contrast-enhancing mass lesion of the cervix of a 49-year-old patient.

Corresponding PET (b) and fused PET/MRI images (c) demonstrate elevated FDG-uptake. The lesion shows corresponding diffusion impairment in DWI (d_1, b = 1000) and low signal intensity in the ADC map (zoom image d₂).

Figure 2. Scatter plot demonstrating a significant inverse correlation between the ADC_min and the SUV_max for primary cervical cancer lesions and associated lymph node metastases.

(n = 21; R = −0.692; p<0.05).

Figure 3. Scatter plot showing a significant inverse correlation between the ADC_min and the SUV_max for primary and recurrent cervical cancer lesions.

(n = 12; R = −0.628; p<0.05).

Figure 4. T1 weighted post-contrast sagittal 3D VIBE (a) and fused PET/MRI image (b) of an inhomogeneously contrast-enhancing and FDG avid cervical cancer lesion.

Image c and d show corresponding tracer uptake in PET (c) and restricted diffusion in DWI (d₁) with low signal intensity on the corresponding ADC map (d₂).