Final report on comparison between Tc-99m MAA SPECT and MDCT pulmonary angiography in patients with pulmonary embolism - Multicenter trial study

Objectives To retrospectively compare 99mTc-MAA lung perfusion SPECT with multidetector CT pulmonary angiography (CTPA) regarding the number of affected segmental and subsegmental pulmonary arteries in patients with acute PTE or CPTE.

Methods We retrospectively reviewed the results of Tc-99m pulmonary MAA and CTPA using a 4-row or more MDCT in PTE pts at the 9 hospitals between 1996 and 2009. A total of 121 patients (32-79 y; mean age 60.5 y) were enrolled. Radioactive gas ventilation/99mTc-MAA SPECT and CTPA images were interpreted by three NM physicians and two experienced radiologists, respectively. The CTPA criteria of PTE were as follows; visualization of the thrombus, pouch defect, abrupt narrowing, obstruction, perfusion abnormality, intimal irregularity, poststenotic dilatation, webs and bands, recanalization, calcified thrombus. Semi-quantification was done by using a scoring system (defect score: DS) with a maximal sore of 17 segments.

Results The DS values in pts with acute PTE were 9.81 in CTPA and 7.15 in SPECT, but the DS values in pts with CPTE were 3.09 in CTPA and 6.00 in SPECT. Only eight of 65 acute PTE pts (12.3%) with thrombolysis and anticoagulant therapy had a complete resolution on repeated SPECT studies. Only 4 of 121 pts (3.3%) with acute PTE had a final diagnosis of chronic PTE hypertension. SPECT showed improvement and aggravation of the disease more accurately than CTPA.

Conclusions Tc-99m MAA SPECT was more accurate than CTPA in monitoring PTE patients.

Research Support The Japanese Society of Nuclear Medicin