After approval in 1989 of PET imaging with rubidium-82 in the US, several meta-analyses were performed in thousands of patients aiming at comparing diagnosis of both SPECT and PET technologies (ref. Chatal story of rubidium-82). It is thus possible to compare these two imaging techniques.

PET imaging with rubidium-82 showed a higher diagnosic specificity than SPECT imaging technology with technetium-99m (85 vs 67%) in overweight or obese patients and in women with large breasts, due to better spatial resolution, coincidence detection and accurate attenuation correction of PET.

Moreover, PET image quality has been shown to be better than SPECT, making PET images easier to interpret. The results were deemed clearly normal or abnormal in 96% of PET images, compared with 81% of SPECT images resulting in fewer images with inconclusive interpretation.

In particular, PET imaging with rubidium-82 allows for absolute quantification of myocardial blood flow, which is quite useful in the clinical situation of tritroncular coronary artery disease in which diagnostic sensitivity can be significantly lower when using SPECT imaging with technetium-99m.

Finally, due to the short half-life of rubidium-82, patient exposure to radiation is 2 to 3 times lower with PET compared to SPECT with technetium-99m.

 

  • Figure 1 : Image of a coronal myocardial slice obtained with conventional imaging using the latest generation CZT gamma camera and technetium-99m in an obese patient with diabetes. The decreased uptake in the lower part (red arrow) does not correspond to decreased coronary blood flow but to an artifact caused by inaccurate attenuation correction (false positive result).

 

 

  • Figure 2 : Image of a coronal myocardial slice obtained in the same patient with a PET/CT system and rubidium-82. Myocardial uptake is evenly distributed corresponding to a normal image (true negative result).