Diffusion Weighted Imaging in Prostate Cancer

Diffusion Weighted Imaging in Prostate Cancer

Disclosure Information Vikas Kundra, M.D, Ph.D. No financial relationships to disclose.

Education Goals and Objectives To describe the utility of diffusion-weighted imaging in localizing cancer involving the prostate gland.

T2 Prostate Carcinoma T2 T1

DWI basic principal In vitro: Free diffusion secondary to constant Brownian motion. In tissues: Restricted diffusion- affected by factors such as vascularity, cellularity and membrane integrity.

DWI basic principal In vitro: Free diffusion secondary to constant Brownian motion. In tissues: Restricted diffusion- affected by factors such as vascularity, cellularity and membrane integrity.

DWI basic principal Static water molecules Moving water molecules Blood vessels Signal 50 Extracellular space - cysts, gallbladder, etc Intracellular space Extracellular space- hypercellular tissue b values

Signal Faster/longer motion (macro) Blood vessels 50 Cellular level diffusion Extracellular space - cysts, gallbladder, etc b values Intracellular space Extracellular space- hypercellular tissue

Effect of b o value b o = 1000 b o = 700 b o = 500 b o = 300 D W I A D C

Diffusion-weighted Imaging T2 ADC

Tumors can have heterogeneous ADC, and can look dark on DWI due to T2-shine through T1 T2 DWI ADC

Studies Using DWI Imaging Various techniques & ADC cutoff Kim et al JCAT 2007 De Souza et al Brit J. Rad 2007 Magnet Coil bo Th mm 3T Phased array 0, 1000 1.5T ERC 0, 300, 500, 800 4 35 P Z n ADC CA ADC B9 T Z 4 30 P Z T Z ADC cutoff Sens Spec 1.32 1.97 1.67 94 91 1.37 1.79 1.61 90 84 1.3 1.71 1.6 87 72 Reinsberger 1.5T ERC 0, 300, 4 42 P 1.19 1.51 1.26 et al AJR 500, Z ADC 2007 800 >30% in voxel 67 >70% in voxel 93 MRS >30% in voxel 81 >70% in voxel 93 T 1.31 Amount of pathology in voxel influences Z detectability Miao et al. Eur J of Rad 2007 Tanimoto et al JMRI 2007 3T Phased Array 0, 300, 600 1.5T ERC 0, 1000 5 37 visual DWI T2 5 83 P Z visual T2 T2+DWI T2+DWI+DCE Visual imaging rather than ADC cutoffs may be helpful 1.46 84 75 73 84 95 60 57 64 73 81 73 54 85 74

More Recent Studies Have Reported Similar Sensitivities and Specificities for DWI alone and Suggest DWI adds to Sensitivity and Specificity of T2-weighted imaging Sensitivity (%) Specificity (%) N (pts) Article T2 51 61 37 Yoshimitsu, JMRI 2008 T2/DWI 71 61 T2 77 66 29 Ren, Eur, Radio 2009 T2/DWI 87 83 T2 74/67/67 79/77/57 52 Lim, Radiology 2009 T2/DWI 88/81/78 88/89/63-3 readers T2 73 65 68 Ren, JMRI 2009 T2/DWI 82 78

Gleason 3+3 not initially seen, in retrospect can be seen at apex T1 T2 DWI ADC

DWI imaging can identify prostate cancer in the Central Zone, but sensitivity is lower in the CZ and cut-off values may be lower (Kim JMRI 2008) Zone Sequence Sensitivity (%) Specificity (%) N (pts) Article PZ T2 57 80 51 Haider, AJR 2007 PZ T2/DWI 87 91 51 CZ T2 36 90 51 Haider, AJR 2007 CZ T2/DWI 41 92 51 PZ, ADC 1.28 DWI 98 81 47 Kim JH, JMRI 2008 CZ, ADC DWI 81 87 47 1.11 CZ T2 13 8 Shimofusa, 2005 CZ DWI 63 8

Central Zone Tumors are often Missed by Imaging

BPH can have low ADC DWI ADC

Diffuse Prostate Cancer in PZ inseparable from CZ T2 DWI ADC

DW Imaging may Identify Invasion into Adjacent Organs Seminal Vesicle Invasion Sequence Sensitivity (%) Specificity (%) N (pts) Article SV T2 77 66 29 Ren, Eur Rad 2009 SV DWI 80 71 29 SV T2/DWI 87 83 29 SV, reader 1,2 T2 87,57 87,81 30 Kim CK, JMRI 2008 SV, reader 1,2 T2/DWI 93,67 97,96 30

DW imaging may identify urinary bladder neck invasion Ren et al (JMRI 2009) reported ADC values for urinary bladder invasion of 0.963 + 0.155 x 10 3 mm 2 /sec vs 1.517 + 0.103 x 10 3 mm 2 /sec for normal urinary bladder wall (P < 0.001). AUC for T2-weighted imaging plus DW imaging (0.861) was larger than that for T2-weighted imaging alone (0.734) or for DW imaging alone (0.703) (P < 0.001).

Seminal Vesicle Invasion T2 DWI ADC

DW Imaging Confounding Factors Benign conditions (Xu et al Magn Res Med 2009) BPH Prostatitis Susceptibility artifact (Riches et al NMR Biomed 2009) Tissue boundaries Blood Increased vascular flow within the tumor (Van et al Br J Radio 2008) Motion (Lim et al Radiology 2009) Well differentiated tumor (Yoshimitsu et al JMRI 2008)

Diffusion-weighted Imaging - Hemorrhage can cause susceptibility artifact T1 T2 ADC

DWI-Hemorrhage can cause susceptibility artifact T1 Blood DWI T2 Tumor T2 ADC ADC

Hemorrhage resulted in difficulty identifying tumor, but seen on ADC at apex T1 T2 DWI ADC

DWI vs Other Functional Modalities (DCE-MR or MRS) Results have been mixed Whether one modality is better Whether combining with other functional modalities improves sensitivity and specificity Chen et al. Acta Radiol. 2008 Reinsberg SA AJR Am J Roentgenol. 2007 Mazaheri Y Radiology. 2008 Kim CK Abdom Imaging. 2009 Kim CK AJR 2008 Tamada T Radiology. 2008

DWI can identify Lymph Nodes Small FOV Large FOV

DW Imaging Potential Clinical Impact DWI imaging may Improve tumor localization in patients with a prior failed biopsy, but elevated PSA (3T, T2+DWI sensitivity 54-81% vs 81-84% T2 only (Park et al. Invest Radiol. 2008) Aid guiding biopsy in patient with failed prior biopsy, but elevated PSA Tumor localization for radiation therapy planning, especially for finer spatial resolution therapies such as proton beam therapy

DW Imaging Potential Clinical Impact DWI imaging may Aide tumor localization in areas of hemorrhage (DiBiase et al Int J Radiat Oncol Biol Phys 2002) Improve tumor staging Such as invasion into adjacent structures Potentially identifies tumors of higher grade (DeSouza et al. Clin Radiol. 2008) Detect Recurrence following therapy such as External beam radiation (Kim CK, Abdominal Imaging 2009) High frequency ultrasound (Kim CK, AJR 2008)

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