Ah Young Park, Presenter: Nothing to Disclose

Choon Sik Yoon, Abstract Co-Author: Nothing to Disclose

Jeong Ah Ryu MD, PhD, Abstract Co-Author: Nothing to Disclose

Sungjun Kim, Abstract Co-Author: Nothing to Disclose

Yaena Kim MD, Abstract Co-Author: Nothing to Disclose

Jung Hyun Kang, Abstract Co-Author: Nothing to Disclose

Hee Woo Cho MD, Abstract Co-Author: Nothing to Disclose

Young Han Lee MD, Abstract Co-Author: Nothing to Disclose

Ho-Taek Song MD, Abstract Co-Author: Nothing to Disclose

Jin-Suck Suh MD, Abstract Co-Author: Nothing to Disclose

To validate which mode of ultrasonography (US) among conventional (CV), spatial compound (SC), and tissue-harmonic (TH) ones is most optimal in detecting Implanon® with respect to the property of generating posterior acoustic shadowing (PAS).

A total of 21 patients, who were referred for removal of Implanon®, underwent US in the 3 different modes, and the rods were detected during the scan for all the patients. A representative transverse image of the rod with the use of each mode for the 21 patients was obtained at the identical location. The resultantly obtained 63 images were divided into set CV, SC, and TH according to the mode by which the images were obtained. The images were reviewed by two experienced musculoskeletal radiologists (R1 and R2) and two resident trainees (R3 and R4), who did not perform US, independently in randomized order. The observers scored confidence for presence of PAS using a 5-point scale in probability order from 1 (definitely absent) to 5 (definitely present). The observers also recorded whether the rods were visualized or not irrespective of presence of PAS to calculate detection rate of each mode. The average scores of PAS obtained from the 3 different modes for each observer were measured and compared among the modes with the use of Friedman test. Detection rates of each mode were calculated and compared with each other.

Average scores of PAS from set CV, SC, TH for the experienced observers were as follows: 2.9, 2.1, 4.8 for R1; 3.4, 2.6, 5.0 for R2. Average scores of PAS from set CV, SC, TH for the less experienced observers were as follows: 3.0, 3.0, 5 for R3; 3.0, 2.8, 4.4 for R4. The detection rates in percentage of set CV, SC, TH for the observers were as follows: 90.5 (19/21), 66.7 (14/21), 100(21/21) for R1; 80.9 (17/21), 76.2 (16/21), 100 (21/21) for R2; 52.4 (11/21), 61.9 (13/21), 100 for R3; 52.4 (11/21), 52.4 (11/21), 100 (21/21) for R4. Statistically, the TH mode was significantly superior compared with the remaining modes in depiction of PAS and in detection rate for all observers.

TH mode is most suitable in detecting subdermal contraceptive implant rods in wide focal zone condition due to its superiority in generating PAS.

Tissue-harmonic mode should be used as a mode of choice to detect Implanon® in the wide focal zone condition which is now widely adopted as a default mode for many vendors.

Park, A, Yoon, C, Ryu, J, Kim, S, Kim, Y, Kang, J, Cho, H, Lee, Y, Song, H, Suh, J, Determination of Most Optimal Mode for Ultrasound Detection of Subdermal Contraceptive Implant Rods in Wide Focal Zone Condition: Conventional vs Spatial Compound vs Tissue-Harmonic Modes.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11006315.html