Vergleich von relativer ¹⁸FDG-Aufnahme mit metabolischer Rate (MRGlukose) im Myokard bei KHK, klassifiziert mit ^99mTc-MIBI

Zusammenfassung

Ziel: Sind a) die typischen Perfusions-/Stoffwechsel-Befundmuster (Match, Mismatch) aus dem Vergleich ^99mTc-MIBI-/¹⁸FDG-Speicherung (normiert auf das Perfusionsmaximum) auch für ^99mTc-MIBI-/regionale MRGlukose (Glu; Auswertung nach Patlak) zu finden und ist b) rMGIu im Perfusionsmaximum für alle Schweregrade der KHK im Richtwertebereich? Methoden: Bei 55 Patienten mit KHK wurden die relative myokardiale Speicherung von ^99mTc-MIBI (in Ruhe; SPECT) und von ¹⁸FDG (nach Glukoseladung, PET) vergleichend zu rMRGIu (in fxmol/100 g/min) in je 13 Segmenten des linken Ventrikels (insgesamt 715 Segmente) bestimmt. Ergebnisse: Die rMRGIu zeigte Streubreiten von bis zu 51 %. Sie nahm in der Reihenfolge normal (52,7 ± 27,3 fxmol/100 g/min), mismatch (45,3 ± 17,3), intermediär (35,2 ± 12,4) nach match (»avital«, 26,7 ± 13,3) signifikant (p <0,01) ab. In 26% der Perfusionsmaxima war MIRGIu <40 fxmol/ 100 g/min, darunter nur bei fünf Dreigefäßerkrankungen (von 28) <30 fxmol. Die Serumglukosewerte zeigten bei drei dieser fünf Patienten eine ungenügende Antwort auf die orale Glukosebelastung. Schlußfolgerung: rMIRGIu erbrachte bei KHK die gleichen Fluß/Stoffwechsel-Befundmuster wie die relative FDG-Speicherung. Der größere Aufwand für die Berechnung von rMRGIu ergab keinen diagnostischen Vorteil. Das Perfusionsmaximum (100% MIBI) als Bezugswert für FDG (= 100% FDG) war auch bei euglykämisch eingestellten Patienten mit Dreigefäßerkrankungen verläßlich.

Summary

Aim: Are i) typical patterns of perfusion/metabolism (match, mismatch), gained from relative ^99mTc-MIBI vs relative ¹⁸FDG uptake (normalized to the perfusion maximum) obtainable also vs absolute MRGIu and is ii) rMRGIu in the segment of maximum perfusion (MIBI = 100%) within the normal range for all degrees of coronary artery disease (CAD)? Methods: In 55 non-diabetic patients with CAD, relative myocardial perfusion (^99mTc MIBI SPECT at rest) and relative ¹⁸FDG uptake (PET after glucose load) were used to separate for various flow/metabolism constellations. In addition, regional glucose metabolic rate (rMRGIu in ixmol/ 100 g/min; dynamic-graphic analysis from Gambhir/Patlak) was determined in 13 segments of the left ventricle each (i. e., in a total of 715 segments). Results: rMRGIu revealed wide standard deviations (up to 51%). It decreased from normal (52.7 ± 27.3 (xmol/100 g/min), mismatch (45.3 ± 17.3) and intermediate (35.2 ± 12.4) to match (»non viable«; 26.7 ± 13.3) significantly (p <0.01). In 26% of the perfusion maxima, MRGIu was <40 (xmol/100 g/min. Out of these, only in five patients (of 28) with 3-vessel disease, it was even smaller (<30 (xmol). In three out of the latter, glucose blood levels were below euglycemia. Conclusion: rMRGIu in CAD revealed an identical perfusion/metabolism pattern as relative ¹⁸FDG uptake. Thus, the higher efforts employed to compute rMRGIu do not yield diagnostic advantage. The segmental perfusion maximum, used for normalization of relative ¹⁸FDG uptake (100% MIBI uptake = 100% FDG uptake) was reliable in euglycemic patients even with 3-vessel disease.

Schlüsselwörter

Stoffwechselrate Glukose (rMRGIu) - ¹⁸FDG-PET - ^99mTc-MIBI-SPECT - CAD

Keywords

Metabolic rate glucose (rMRGIu) - ¹⁸FDG-PET - ^99mTc-MIBI-SPECT - CAD

^* Diese Arbeit enthält Teile der Inauguraldissertation von Frau cand. med. Y. Foroutan.

^* Medizinischen Klinik I der RWTH, Klinikum Aachen, Deutschland

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