Comparison between Tc-99m N-NOET and Tl-201 in the assessment of patients with known or suspected coronary artery disease.
BACKGROUND
Technetium 99m N-ethoxy-N-ethyl dithiocarbamate (N-NOET) is a new radionuclide tracer for cardiac single photon emission computed tomography (SPECT) imaging. It combines the advantageous properties of a Tc-99m agent with the redistribution characteristics of thallium 201. We directly compared the two agents in patients with known or suspected coronary artery disease.


RESULTS
Fifty patients underwent treadmill exercise Tc-99m N-NOET and Tl-201 SPECT studies. Images were acquired at stress, redistribution, and reinjection. Segmental analysis was carried out, and direct comparisons were made with corresponding segments. A stress score index was calculated and compared with the degree of lung uptake for each patient. From the 50 patients, 2657 of 2664 exercise, redistribution, and reinjection segments (99%) were interpreted. There was excellent agreement between the two modalities (weighted kappa = 0.83). Of the patients, 24 demonstrated reversible ischemia by Tl-201 SPECT reinjection imaging, of which Tc-99m N-NOET stress-redistribution imaging correctly identified 14 (58%); this improved significantly to 20 patients (83%) ( P = .03) when a reinjection protocol was used. A higher stress score index was seen in those patients with significant lung uptake (lung-heart ratio > or =0.6) after Tc-99m N-NOET stress imaging (1.6 vs 1.3, P = .03).


CONCLUSIONS
SPECT imaging with Tc-99m N-NOET is comparable to Tl-201 for the diagnosis of coronary artery disease. Significant lung uptake with stress Tc-99m N-NOET may also indicate the severity of disease.
Jeetley
Paramjit
P
Department of Cardiovascular Medicine, Northwick Park Hospital, Watford Road, Harrow, Middlesex HA2 0HX, UK.
Sabharwal
Nikant K
NK
Soman
Prem
P
Kinsey
Chris
C
Raval
Usha
U
Bhonsle
Uday
U
Lahiri
Avijit
A
D003324:Coronary Artery Disease / Q000175:diagnosis / Q000000981:diagnostic imaging*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013793:Thallium; D013859:Thiocarbamates; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D006113:United Kingdom
D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D013859:Thiocarbamates; C027549:thallium chloride; D013793:Thallium; C093922:technetium Tc 99m, bis(N-ethoxy-N-ethyldithiocarbamato)nitrido-