Attenuation correction for myocardial perfusion imaging

Summary

Aim: We investigated the impact of photon attenuation in myocardial perfusion imaging with SPECT and PET in patients with coronary artery disease. In fact, the regional tracer distribution can be quantitatively assessed by polar map analysis if the effects of photon attenuation are accounted for. PET imaging permits accurate measurement of and correction for photon attenuation, whereas results of attenuation correction in SPECT imaging have been inconsistent. Patients, methods: We compared photon attenuation in resting perfusion imaging studies with SPECT (^99mTc-sestamibi) and PET (¹³N-ammonia) from 21 patients. Transaxial images were reconstructed with and without attenuation correction and reoriented into short axis images. Polar map analysis was utilized to generate regional tracer uptake in six anatomical segments. Results: Average segmental photon attenuation calculated as the ratio of counts in corrected and uncorrected images was 7.2 ± 1.4 in SPECT and 14.0 ± 3.1 in PET imaging (p <0.01). This attenuation factor was significantly related to body mass index for both methods (p <0.001). While attenuation correction for SPECT imaging did compensate for attenuation effects in the inferior wall (from –15% to +6% vs. PET), relative tracer uptake in the anterior wall in SPECT images was significantly reduced after attenuation correction (from –2% to –18% vs. PET, p <0.01). Conclusion: Differential effects of attenuation correction for myocardial SPECT perfusion imaging need to be considered when algorithms designed to compensate effects of photon attenuation in SPECT imaging are employed in clinical practice.

Zusammenfassung

Ziel: Wir untersuchten das Ausmaß der Photonenattenuation bei Myokardperfusionsstudien mittels SPECT und PET. Beide Methoden erlauben eine Quantifizierung der regionalen Isotopverteilung mit Hilfe der Polar Map Analyse, sofern die Effekte der Weichteilattenuation berücksichtigt werden. Während PET eine akkurate Messung der Photonenattenuation und demzufolge eine verlässliche Attenuationskorrektur erlaubt, sind die Resultate der Attenuationskorrektur mittels SPECT inkonsistent. Patienten, Methoden: Wir verglichen die Photonenattenuation von SPECT (^99mTc-Sestamibi) und PET (¹³N-Ammonika) Myokardperfusionsstudien in 21 Patienten mit koronarer Herzerkrankung. Transaxiale Bilder wurden mit und ohne Attenuationskorrektur rekonstruiert und in Kurzachsen Schnitte reorientiert. Unter Anwendung der Polar Map Analyse wurde die regionale Isotopverteilung in sechs anatomischen Segmenten untersucht. Ergebnisse: Die durchschnittliche segmentale Photonenattenuation (Verhältnis der Zählrate in korrigierten zu unkorrigierten Bildern) betrug 7.2 ± 1.4 in den SPECT Studien und 14.0 ± 3.1 in den PET Studien (p <0.01). Dieser Attenuationsfaktor korrelierte bei beiden Methoden signifikant mit der Körperoberfläche (p <0.001). Während die Attenuationskorrektur mittels SPECT die Effekte der Attenuation der inferioren Wand kompensierte (von –15% auf +6% im Vergleich zu PET), war die relative Isotopaufnahme nach Attenuationskorrektur in der Vorderwand signifikant herabgesetzt (von –2% auf –18% im Vergleich zu PET, p <0.01). Schlussfolgerung: Die unterschiedlichen Effekte der Attenuationskorrektur bei Myokardperfusionsstudien mittels SPECT müssen beim klinischen Einsatz von Algorithmen zur Kompensation von Attenuationsartefakten berücksichtigt werden.

Keywords

Myocardial perfusion imaging - SPECT - PET - attenuation correction - polar map analysis

Schlüsselwörter

Myokardperfusion - SPECT - PET - Schwächungskorrektur - Polar- Map-Analyse

• References

• 1 Beanlands RS, Muzik O, Hutchins GD. et al. Heterogeneity of regional nitrogen 13-labeled ammonia tracer distribution in the normal human heart: comparison with rubidium 82 and copper 62-labeled PTSM. J Nucl Cardiol 1994; 1: 225-35.
• 2 Corbett JR, Ficaro EP. Attenuation corrected cardiac perfusion SPECT. Curr Opin Cardiol 2000; 15: 330-6.
• 3 Demer LL, Gould KL, Goldstein RA. et al. Assessment of coronary artery disease severity by positron emission tomography. Comparison with quantitative arteriography in 193 patients. Circulation 1989; 79: 825-35.
• 4 Duvernoy CS, Ficaro EP, Karabajakian MZ. et al. Improved detection of left main coronary artery disease with attenuation-corrected SPECT. J Nucl Cardiol 2000; 7: 639-48.
• 5 Ficaro EP, Fessler JA, Shreve PD. et al. Simultaneous transmission/emission myocardial perfusion tomography. Diagnostic accuracy of attenuation- corrected ^99mTc-sestamibi single photon emission computed tomography. Circulation 1996; 93: 463-73.
• 6 Ficaro EP, Wackers FJT. Should SPET attenuation correction be more widely employed in routine clinical practice?. J Nucl Med 2002; 29: 409-12.
• 7 Freedman N, Schechter D, Klein M. et al. SPECT attenuation artifacts in normal and overweight persons: insights from a retrospective comparison of Rb-82 positron emission tomography and 201TI SPECT myocardial perfusion imaging. Clin Nucl Med 2000; 25: 1019-23.
• 8 Fukuchi K, Sago M, Nitta K. et al. Attenuation correction for cardiac dual-head gamma camera coincidence imaging using segmented myocardial perfusion SPECT. J Nucl Med 2000; 41: 919-25.
• 9 Gallowitsch HJ, Sykora J, Mikosch P. et al. Attenuation- corrected thallium-201 single photon emission tomography using a gadolinium-153 moving line source: clinical value and the impact of attenuation correction on the extent and severity of perfusion abnormalities. Eur J Nucl Med 1998; 25: 220-8.
• 10 Gilland DR, Jaszczak RJ, Greer KL. et al. Transmission imaging for nonuniform attenuation correction using a three-headed SPECT camera. J Nucl Med 1998; 39: 1105-10.
• 11 Go RT, Marwick TH, MacIntyre WJ. et al. A prospective comparison of rubidium-82 PET and thallium- 201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease. J Nucl Med 1990; 31: 1899-905.
• 12 Grossman GB, Garcia EV, Bateman TM. et al. Quantitative ^99mTc sestamibi attenuation-corrected SPECT: development and multicenter trial validation of myocardial perfusion stress genderindependent normal database in an obese population. J Nucl Cardiol 2004; 11: 263-72.
• 13 Hansen CL, Siegel JA. Attenuation correction of thallium SPECT using differential attenuation of thallium photons. J Nucl Med 1992; 33: 1574-7.
• 14 Harel F, Genin R, Daou D. et al. Clinical impact of combination of scatter, attenuation correction, and depth-dependent resolution recovery for 201Tl studies. J Nucl Med 2001; 42: 1451-6.
• 15 Heller GV, Links J, Bateman TM. et al. American Society of Nuclear Cardiology and Society of Nuclear Medicine joint position statement: attenuation correction of myocardial perfusion SPECT scintigraphy. J Nucl Cardiol 2004; 11: 229-301.
• 16 Hendel RC, Berman DS, Cullom SJ. et al. Multicenter clinical trial to evaluate the efficacy of correction for photon attenuation and scatter in SPECT myocardial perfusion imaging. Circulation 1999; 99: 2742-9.
• 17 Kluge R, Sattler B, Seese A. et al. Attenuation correction by simultaneous emission – transmission myocardial single photon emission tomography using a technetium-99m-labelled radiotracer: impact on diagnostic accuracy. Eur J Nucl Med 1997; 24: 1107-14.
• 18 LaCroix KJ, Tsui BM, Frey EC. et al. Receiver operating characteristic evaluation of iterative re-construction with attenuation correction in ^99mTc – sestamibi myocardial SPECT images. J Nucl Med 2000; 41: 502-13.
• 19 Ljungberg M, Strand SE. Attenuation and scatter correction in SPECT for sources in a nonhomogeneous object: a monte Carlo study. J Nucl Med 1991; 32: 1278-84.
• 20 Nekolla SG, Miethaner C, Nguyen N. et al. Reproducibility of polar map generation and assessment of defect severity and extent assessment in myocardial perfusion imaging using positron emission tomography. Eur J Nucl Med 1998; 25: 1313-21.
• 21 O´Connor MK, Kemp B, Anstett F. et al. A multicenter evaluation of commercial attenuation compensation techniques in cardiac SPECT using phantom models. J Nucl Cardiol 2002; 9: 361-76.
• 22 Ohyama Y, Tomiguchi S, Kira T. et al. Phantom evaluation of scatter and attenuation correction in thallium-201/technetium-99m acquisition in myocardial perfusion single photon emission computed tomography. Radiat Med 2001; 19: 81-7.
• 23 Sand NP, Bottcher M, Madsen MM. et al. Evaluation of regional myocardial perfusion in patients with severe left ventricular dysfunction: comparison of 13N-ammonia PET and ^99mTc sestamibi SPECT. J Nucl Cardiol 1998; 5: 4-13.
• 24 Savi A, Rossetti C, Gilardi MC. et al. [Correction measured by attenuation in tomographic heart studies with single photon emission with thallium 201. Comparison with positron emission tomographic studies with ammonium marked with nitrogen]. Radiol Med (Torino) 1999; 98: 36-42.
• 25 Schelbert HR, Wisenberg G, Phelps ME. et al. Noninvasive assessment of coronary stenoses by myocardial imaging during pharmacologic coronary vasodilation. VI. Detection of coronary artery disease in human beings with intravenous 13N-ammonia and positron computed tomography. Am J Cardiol 1982; 49: 1197-207.
• 26 Shotwell M, Singh BM, Fortman C. et al. Improved coronary disease detection with quantitative attenuation- corrected 201Tl images. J Nucl Cardiol 2002; 9: 52-62.
• 27 Van Train KF, Maddahi J, Berman DS. et al. Quantitative analysis of tomographic stress thallium- 201 myocardial scintigrams: a multicenter trial. J Nucl Med 1990; 31: 1168-79.
• 28 Vidal R, Buvat I, Darcourt J. et al. Impact of attenuation correction by simultaneous emission/ transmission tomography on visual assessment of 201Tl myocardial perfusion images. J Nucl Med 1999; 40: 1301-9.
• 29 Wallis JW, Miller TR, Koppel P. Attenuation correction in cardiac SPECT without a transmission measurement. J Nucl Med 1995; 36: 506-12.