Kambiz Motamedi MD, Presenter: Nothing to Disclose

Sean Darcy MD, Abstract Co-Author: Nothing to Disclose

Kira Chow MD, Abstract Co-Author: Nothing to Disclose

Leanne Louise Seeger MD, Abstract Co-Author: Nothing to Disclose

Shantanu Sinha PhD, Abstract Co-Author: Nothing to Disclose

To determine whether ADC maps obtained from in vivo EP-DWI of the knee could aid in the differential diagnosis of fluid containing spaces of the knee.

All scans were performed in a 1.5T GE LX scanner. 20 SE EP-DW images were acquired with a linear coil (since this particular scanner had only one fast receiver), with TR/TE/FOV :: 10000ms/72ms/18mm, 128x128 matrix , 18cm FOV, 5mm thick, 2 Avg. and two b-values of 0 and 700 s/mm², with 2.3 min scan time. Two standard liquids, acetonitrile (AN) and dimethylsulfoxide (DMSO) were used for calibration purposes. 72 knee images of patients presenting with pain/trauma, were analyzed, with 71 suprapatellar joint effusions (JE), 11 Baker cysts (BC), 6 infrapatellar bursae (IB) and 2 parameniscal cysts (PM). Several ROI’s were also measured for control purposes in the lateral gastrocnemious. ADC’s were calculated by offline post-processing of ROI’s drawn on the lesions, using the equation, ADC = {ln(S0/S700)}/700, and presented here in units of 10˜³mm²/sec.

ADC’s of AN and DMSO were estimated as 4.13±0.11 and 0.66±0.02 compared to literature values of 4.37 and 0.73 respectively. Image quality of the DW knee images was sufficiently good in terms of fat suppression, distortion, ghosting and SNR for meaningful ADC’s to be calculated. The ADC’s of JE’s, BC’s, IB’s and PM cysts were found to be 2.81±0.36, 2.81±0.65, 2.94±0.28 and 2.16 respectively, all consistent with a high fraction of free water, with ADC’s close to 2.29 of water at 27ºC and 2.65±0.3 for cystic breast lesions. A value of 1.84±0.57 for muscle reflects considerably more hindrance to diffusive motion of protons (compare to ~1.96 for prostate peripheral zone muscle), a factor of considerable importance in low ADC’s (~1.6±0.36 for malignant breast lesions) of cancerous lesions which have high cellularity.

In-vivo Diffusion imaging of the human knee is feasible and the ADC’s were sufficiently distinct from that of normal tissue to show good potential as a tool for differential diagnosis of simple fluid containing spaces in the knee.

Motamedi, K, Darcy, S, Chow, K, Seeger, L, Sinha, S, Echo-Planar, Diffusion-weighted Imaging (EP-DWI), and ADC Maps in the Differential Diagnosis of Lesions of the Knee.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4413368.html