Preoperative assessment of relative pulmonary lobar perfusion fraction in lung cancer patients^[*]

Summary

Preoperative quantification of (relative) pulmonary lobar perfusion fraction using scintigraphy is established in predicting lung function after pulmonary surgery. Aim was to develop an easy and truly anatomical method for relative pulmonary lobar perfusion fraction quantification using SPECT/CT and to compare results with those from planar analyses in lung cancer patients. Patients, methods: 36 patients with operable lung cancer, borderline lung function referred to pre-operative quantification. Perfusion SPECT-data were acquired p.i. of 163±9 MBq ^99mTc-MAA, subsequent low-dose-CT (SymbiaT, Siemens). Iterative Flash3D-reconstruction, manual 3D segmentation of all lobes using PMOD. VOI transfer to coregistered perfusion SPECTdata, calculation of lobar fractions. Modelbased calculation of relative lobar fractions based on planar data, analysis of planar vs. 3D results using t-test. Results: Significant differences (p<0.05) between the results from 3D method and planar imaging were found for right upper and middle lobe and both lower lobes. Maximum differences ranged from 10.9% (left upper lobe) to 22.9% (right upper lobe). Conclusions: Relative pulmonary lobar perfusion fraction can easily be obtained by an anatomically driven 3D quantification. Results yielded by this method and the traditional planar approach differed greatly, possibly affecting eligibility for lung surgery in individual patients. Considering these results a 3D approach should be used whenever possible.

Zusammenfassung

Die Quantifizierung der (relativen) lobären Perfusionsanteile ist ein etabliertes Verfahren in der präoperativen Abschätzung der postoperativen Lungenfunktion. Ziel der Studie ist die Entwicklung einer auf der individuellen Patientenanatomie basierenden Methode zur Beurteilung der relativen Perfusionsanteile mittels SPECT/CT. Zudem sollen die Ergebnisse einer planaren gegenüber einer 3D-Analyse verglichen werden. Patienten, Material, Methoden: 36 Patienten (operables Bronchialkarzinom, grenzwertige Lungenfunktion), überwiesen zur prä-OP-Perfusions-SPECT. SPECT-Akquisition p.i. von 163±9 MBq ^99mTc- MAA, anschließend low-dose-CT (SymbiaT, Siemens). Iterative Flash-3D-Rekonstruktion, manuelle Segmentierung der low-dose-CT mit PMOD, Transfer der VOIs auf die SPECTStudien, Kalkulation der relativen Lappenanteile. Modellbasierte Kalkulation der relativen Lappenanteile (planare Daten). Berechnung der Mittelwerte der relativen Lappenanteile und der absoluten Differenzen, Analyse der Ergebnisse mittels T-Test. Ergebnisse: Signifikant (p<0,05) unterschiedliche Lappenanteile für rechten Oberlappen, Mittellappen und beide Unterlappen. Maximale Differenzen reichten von 10,9% (linker Oberlappen) bis 22,9% (rechter Oberlappen). Schlussfolgerung: Die relativen lobären Perfusionsanteile können mit der anatomisch-basierten 3D-Quantifizierung relativ einfach bestimmt werden. Die 3D-Ergebnisse weichen teils sehr erheblich von der modellbasierten Berechnung (planare Szintigrafie) ab. Diese Abweichungen können möglicherweise die Indikationsstellung zur Operation beeinflussen, daher sollte – wann immer möglich – präoperativ ein 3D-Ansatz verwendet werden.

Keywords

Quantitative lung perfusion SPECT/CT - 3D-quantification - lung cancer - estimated postoperative FEV 1.0

Schlüsselwörter

Quantitative Lungenperfusions-SPECT/CT - 3D-Quantifizierung - Bronchialkarzinom - postoperativ zu erwartende FEV 1.0

^* Parts of this work have been presented at the annual meetings of the SNMMI and DGN 2013.

^** Daniela Knollmann and Andreas Meyer have contributed equally to this work.

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