Diffusion weighted MRI and 18F-FDG PET/CT in non-small cell lung cancer (NSCLC): does the apparent diffusion coefficient (ADC) correlate with tracer uptake (SUV)?

To investigate the potential correlation of the apparent diffusion coefficient assessed by diffusion-weighted MRI (DWI) and glucose metabolism determined by the standardized uptake value (SUV) at 18F-FDG PET/CT in non-small cell lung cancer (NSCLC). 18F-FDG PET/CT and DWI (TR/TE, 2000/66 ms; b-values, 0 and 500 s/mm(2)) were performed in 41 consecutive patients with histologically verified NSCLC. Analysing the PET-CT data calculation of the mean (SUV(mean)) and maximum (SUV(max)) SUV was performed. By placing a region-of-interest (ROI) encovering the entire tumor mean (ADC(mean)) and minimum ADC (ADC(min)) were determined by two independent radiologists. Results of 18F-FDG PET-CT and DWI were compared on a per-patient basis. For statistical analysis Pearson's correlation coefficient, Bland-Altman and regression analysis were assessed. Data analysis revealed a significant inverse correlation of the ADC(min) and SUV(max) (r=-0.46; p=0.032). Testing the correlation of the ADC(min) and SUV(max) for each histological subtype separately revealed that the inverse correlation was good for both adenocarcinomas (r=-0.47; p=0.03) and squamouscell carcinomas (r=-0.71; p=0.002), respectively. No significant correlation was found for the comparison of ADC(min) and SUV(mean) (r=-0.29; p=0.27), ADC(mean) vs. SUV(mean) (r=-0.28; p=0.31) or ADC(mean) vs. SUV(max) (r=-0.33; p=0.23). The κ-value of 0.88 indicated a good agreement between both observers. This preliminary study is the first to verify the relation between the SUV and the ADC in NSCLC. The significant inverse correlation of these two quantitative imaging approaches points out the association of metabolic activity and tumor cellularity. Therefore, DWI with ADC measurement might represent a new prognostic marker in NSCLC.

Regier M ，Derlin T ，Schwarz D ，Laqmani A ，Henes FO ，Groth M ，Buhk JH ，Kooijman H ，Adam G ... -  《-》

Correlation of the apparent diffusion coefficient (ADC) with the standardized uptake value (SUV) in hybrid 18F-FDG PET/MRI in non-small cell lung cancer (NSCLC) lesions: initial results.

To compare the apparent diffusion coefficient (ADC) in non-small cell lung cancer lesions with standardized uptake values (SUV) derived from combined 18F-fluoro-deoxy-glucose-positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) and those derived from FDG-PET/CT. In 18 consecutive patients with histologically proven NSCLC (17 men, 1 woman; mean age, 61 ± 12 years), whole-body FDG-PET/MRI was performed after whole-body FDG-PET/CT. Regions of interest (ROI) encompassing the entire primary tumor were drawn into FDG-PET/CT and FDG-PET/MR images to determine the maximum and mean standardized uptake value (SUVmax; SUVmean) and into ADC parameter maps to assess mean ADC values. Pearson's correlation coefficients were calculated to compare SUV and ADC values. The SUVmax of NSCLC was 12.3 ± 4.8 [mean ±SD], and the SUVmean was 7.2 ± 2.8 as assessed by FDG-PET/MRI. The SUVmax and SUVmean derived from FDG-PET/CT and FDG-PET/MRI correlated well (R = 0.93; p < 0.001 and R = 0.92; p < 0.001, respectively). The ADCmean of the pulmonary tumors was 187.9 ± 88.8 × 10-5 mm²/s [mean ± SD]. The ADCmean exhibited a significant inverse correlation with the SUVmax (R = -0.72; p < 0.001) as well as with the SUVmean assessed by FDG-PET/MRI (R = -0.71; p < 0.001). This simultaneous PET/MRI study corroborates the assumed significant inverse correlation between increased metabolic activity on FDG-PET and restricted diffusion on DWI in NSCLC.Citation Format:

Heusch P ，Buchbender C ，Köhler J ，Nensa F ，Beiderwellen K ，Kühl H ，Lanzman RS ，Wittsack HJ ，Gomez B ，Gauler T ，Schuler M ，Forsting M ，Bockisch A ，Antoch G ，Heusner TA ... -  《-》

Hybrid [¹⁸F]-FDG PET/MRI including non-Gaussian diffusion-weighted imaging (DWI): preliminary results in non-small cell lung cancer (NSCLC).

To assess the feasibility of non-Gaussian DWI as part of a FDG-PET/MRI protocol in patients with histologically proven non-small cell lung cancer. 15 consecutive patients with histologically proven NSCLC (mean age 61 ± 11 years) were included in this study and underwent whole-body FDG-PET/MRI following whole-body FDG-PET/CT. As part of the whole-body FDG-PET/MRI protocol, an EPI-sequence with 5 b-values (0, 100, 500, 1000 and 2000 s/mm(2)) was acquired for DWI of the thorax during free-breathing. Volume of interest (VOI) measurements were performed to determine the maximum and mean standardized uptake value (SUV(max); SUV(mean)). A region of interest (ROI) was manually drawn around the tumor on b=0 images and then transferred to the corresponding parameter maps to assess ADC(mono), D(app) and K(app). To assess the goodness of the mathematical fit R(2) was calculated for monoexponential and non-Gaussian analysis. Spearman's correlation coefficients were calculated to compare SUV values and diffusion coefficients. A Student's t-test was performed to compare the monoexponential and non-Gaussian diffusion fitting (R(2)). T staging was equal between FDG-PET/CT and FDG-PET/MRI in 12 of 15 patients. For NSCLC, mean ADC(mono) was 2.11 ± 1.24 × 10(-3) mm(2)/s, Dapp was 2.46 ± 1.29 × 10(-3) mm(2)/s and mean Kapp was 0.70 ± 0.21. The non-Gaussian diffusion analysis (R(2)=0.98) provided a significantly better mathematical fitting to the DWI signal decay than the monoexponetial analysis (R(2)=0.96) (p<0.001). SUV(max) and SUV(mean) of NSCLC was 13.5 ± 7.6 and 7.9 ± 4.3 for FDG-PET/MRI. ADC(mono) as well as Dapp exhibited a significant inverse correlation with the SUV(max) (ADC(mono): R=-0.67; p<0.01; Dapp: R=-0.69; p<0.01) as well as with SUV(mean) assessed by FDG-PET/MRI (ADC(mono): R=-0.66; p<0.01; Dapp: R=-0.69; p<0.01). Furthermore, Kapp exhibited a significant correlation with SUV(max) (R=0.72; p<0.05) and SUV(mean) as assessed by FDG-PET/MRI (R=0.71; p<0.005). Simultaneous PET and non-Gaussian diffusion acquisitions are feasible. Non-Gaussian diffusion parameters show a good correlation with SUV and might provide additional information beyond monoexponential ADC, especially as non-Gaussian diffusion exhibits better mathematical fitting to the decay of the diffusion signal than monoexponential DWI.

Heusch P ，Köhler J ，Wittsack HJ ，Heusner TA ，Buchbender C ，Poeppel TD ，Nensa F ，Wetter A ，Gauler T ，Hartung V ，Lanzman RS ... -  《-》

Correlation of simultaneously acquired diffusion-weighted imaging and 2-deoxy-[18F] fluoro-2-D-glucose positron emission tomography of pulmonary lesions in a dedicated whole-body magnetic resonance/positron emission tomography system.

Schmidt H ，Brendle C ，Schraml C ，Martirosian P ，Bezrukov I ，Hetzel J ，Müller M ，Sauter A ，Claussen CD ，Pfannenberg C ，Schwenzer NF ... -  《-》

Correlation of measurements from diffusion weighted MR imaging and FDG PET/CT in GIST patients: ADC versus SUV.

We investigated the correlation relationship between ADCs measured by MRI and SUVs measured by PET/CT of lesions on GIST (gastrointestinal stromal tumor) patients to verify if MR is able to replace or serve as an alternative to PET/CT in GIST staging and treatment monitoring. Between September 2010 and January 2011, five patients with histologically proven metastatic GIST in Queen Mary Hospital, Hong Kong were enrolled into our study. All patients underwent both MRI and PET/CT scans at prognosis. Pearson's correlations of twenty-nine lesions were conducted between 5 pairs of ADCs and SUVs values. Lesions in the liver, peritoneum or bowel loops were found by PET/CT and no extra-abdominal lesion was identified. All twenty-nine lesions are identifiable by MRI with sensitivity of 100%. Significant inverse correlation were found between ADC(mean) and SUV(mean) (P=0.006), ADC(mean) and SUV(max) (P=0.010), ADC(min) and SUV(max) (P=0.014), ADC(min) and SUV(mean) (P=0.026), rADC(min) and rSUV(max) (P=0.047). DWI is comparable to PET/CT in visually detecting the GIST lesions' location. Significant inverse correlations were found between ADCs from DWIBS and SUVs from PET/CT on data of GIST patients. This finding demonstrates that DWI is potentially capable of offering similar information for diagnosis and treatment response evaluating in GIST's patients as PET/CT does. Furthermore, ADC(min), which is determined by single pixel, is not as reliable as ADC(mean), which is weighted average value of the whole lesion volume.

Wong CS ，Gong N ，Chu YC ，Anthony MP ，Chan Q ，Lee HF ，Chu KM ，Khong PL ... -  《-》