Technology gives rise to diagnostic breakthroughs (Part – II)
Several technologies are being combined in novel ways to address previously intractable problems
By: GREG FREIHERR
Using a five-segment model by two blinded observers, perfusion was determined to be present or absent for each modality. The research team reported a high concordance (93%) between the two modalities for the presence as well as the location of the defects: 96% for the antero-septal region, 93% for the infero-posterior region, and 87% for the apical region.
"Potentially, contrast echo has similar accuracies to SPECT, although it is certainly not a clinically proven technique," said Dr. Avijit Lahiri , director of cardiac research at the hospital.
A larger study comparing the two modalities was performed at the University of Texas Southwestern, where harmonic power Doppler imaging (HPDI) and SPECT were performed during rest and pharmacological stress in 123 patients known or suspected to have coronary heart disease . Myocardial perfusion by HPDI was graded for each coronary territory as absent, patchy, or full.
Persistently absent or patchy myocardial perfusion by HPDI between rest and adenosine was interpreted as a fixed defect, whereas any decrease in perfusion grade was interpreted as a reversible defect. Ultrasound and SPECT produced the same conclusions in 83 of 103 (81%) for normal versus abnormal perfusion. Discrepancies occurred mostly in imaging the circumflex, where HPDI identified fixed defects in 33% of patients but SPECT identified only 14%.
"The next stage of development is to assess real-time perfusion, and that is even more exciting because we can watch the contrast agent come and then wash out," said Dr. Sheila K. Heinle, an assistant professor of medicine at the university. "That will possibly give us additional information about coronary flow reserve in conjunction with pharmacologic agents."
Harmonic imaging alone offers substantial advantages over fundamental imaging, with or without micro-bubble contrast. It increases contrast between vessels and background tissues, has spatial and temporal resolution similar to that of gray-scale imaging, and is unaffected by flash artifact. Harmonic imaging also allows increased penetration without loss of detail. The advantage of artifact reduction and greater intrinsic contrast sensitivity is especially apparent when heightening low-contrast lesions.
By: GREG FREIHERR
Using a five-segment model by two blinded observers, perfusion was determined to be present or absent for each modality. The research team reported a high concordance (93%) between the two modalities for the presence as well as the location of the defects: 96% for the antero-septal region, 93% for the infero-posterior region, and 87% for the apical region.
"Potentially, contrast echo has similar accuracies to SPECT, although it is certainly not a clinically proven technique," said Dr. Avijit Lahiri , director of cardiac research at the hospital.
A larger study comparing the two modalities was performed at the University of Texas Southwestern, where harmonic power Doppler imaging (HPDI) and SPECT were performed during rest and pharmacological stress in 123 patients known or suspected to have coronary heart disease . Myocardial perfusion by HPDI was graded for each coronary territory as absent, patchy, or full.
Persistently absent or patchy myocardial perfusion by HPDI between rest and adenosine was interpreted as a fixed defect, whereas any decrease in perfusion grade was interpreted as a reversible defect. Ultrasound and SPECT produced the same conclusions in 83 of 103 (81%) for normal versus abnormal perfusion. Discrepancies occurred mostly in imaging the circumflex, where HPDI identified fixed defects in 33% of patients but SPECT identified only 14%.
"The next stage of development is to assess real-time perfusion, and that is even more exciting because we can watch the contrast agent come and then wash out," said Dr. Sheila K. Heinle, an assistant professor of medicine at the university. "That will possibly give us additional information about coronary flow reserve in conjunction with pharmacologic agents."
Harmonic imaging alone offers substantial advantages over fundamental imaging, with or without micro-bubble contrast. It increases contrast between vessels and background tissues, has spatial and temporal resolution similar to that of gray-scale imaging, and is unaffected by flash artifact. Harmonic imaging also allows increased penetration without loss of detail. The advantage of artifact reduction and greater intrinsic contrast sensitivity is especially apparent when heightening low-contrast lesions.
posted by Heart Scan @ 3:07 AM
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