Preliminary Study Of Respiratory Navigator Coronary Magnetic Resonance Angiography In Coronary Stenosis Evaluation

This study put three respiratory navigator coronary MRA sequences for comparision with Philips Intera Achieva 1.5T MR scanner,then selected an appropriate one to evaluate it's value of coronary stenosis detection.The study was divided into two parts:Part I: Imaging quality evaluation of respiratory navigator coronary MR angiography techniquesObjectives1.To develope methods of resolving the major obstacles in the course of coronary MR angiography(CMRA);2.To probe the flow chart of CMRA;3.To prospectively compare the image quality and feasibility between 3D BTFE\NAG\small slab and dual-IR TSE sequence;3D BTFE\NAG\small slab and BTFE\whole heart sequence.Materials and methodsTwenty-eight cases were divided into two group;twenty-five cases in group A were evaluated with the navigator-gated 3D BTFE\NAG\small slab and dual-IR TSE sequences;11 cases in group B were evaluated with the 3D BTFE\NAG\small slab and BTFE\whole heart sequences(eight cases underwent all the three sequences).For CMRA at 1.5T MR scanner(Intera,Philips),a vectorcardiogram(VCG) trigger was combined with real-time respiratory navigator gating and tracking technique.Signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR),score of image quality and length of targed vessel were assessed among the three sequences.Data were analyzed for statistical differences by using the matched-pairs student T test.Furthermore,twenty cases′sBTFE cine image were used to evaluate the motion of coronary artery. ResultsTwenty-eight cases were analyzed.In group A,lengths of RCA,LM,LAD,LCX of 3D BTFE\NAG\small slab and dual-IR TSE sequence were 97.38\89.14,15.34\14.19,52.50\35.41 and 50.92\49.16mm respectively;SNR, CNR and score of image quality were 108.86\4.66,67.77\28.01 and 3.50\2.54 respectively.In group B,lengths of RCA,LM,LAD,LCX of 3D BTFE\NAG\small slab and BTFE\whole heart sequence were 99.15\107.13,14.41\15.54,59.34\77.38 and 64.45\85.27 mm respectively;SNR, CNR and score of image quality were 128.25\144.72,80.34\84.04 and 3.55\3.18 respectively.From the analyses of cine image,we found that there were correlation between trigger delay,rest period and heart rate;moreover,we draw two empirical formula.ConclusionVCG trigger combined with real-time respiratory navigator gating and tracking can obtain the image of coronary artery reliably.CMRA with 3D BTFE\NAG\small slab is most feasible and the image quality is goodish;while the BTFE\whole heart sequence owns the advantages of revealing longer vessel and large-scale imaging.Part II: Value of coronary stenosis detection by respiratory navigator 3D Balanced Turbo Field Echo SequenceObjectivesTo evaluate the efficiency of CMRA for stenosis detection by respiratory navigator three dimensional Balanced Turbo Field Echo(BTFE) Sequence with the reference of conventional coronary angiography(CAG).Materials and methodsConsecutive 11 patients who suspected coronary aretry diseases were evaluated with respiratory navigator three dimensional BTFE CMRA examination within two weeks before the CAG..Coronary stenosis was graded in two levels as <50% and≥50%,and CMRA and CAG results were compared segment by segment. ResultsFor the differentiation of the coronary stenosis <50% and≥50%,the sensitivity, specificity and accuracy of CMRA was 67%,94% and 84%,respectively.The agree validity and kappa value between the CMRA and CAG were 0.8409 and 0.4914 respectively.ConclusionThe respiratory navigator three dimensional BTFE sequence for CMRA is practical to exclude hemodynamic significant coronary stenosis but limited in quantificationally grading.