PET lung ventilation/perfusion imaging using (68)Ga aerosol (Galligas) and (68)Ga-labeled macroaggregated albumin.

Pulmonary imaging using ventilation/perfusion (V/P) single-photon emission tomography (V/P scan) with Tc-99m-labeled radiotracers is a well-established diagnostic tool for clinically suspected pulmonary embolism (PE). Ga-68 aerosol (Galligas) and Ga-68-labeled macroaggregated albumin (MAA) are potential tracers for positron emission tomography (PET) lung V/P imaging and could display an advantage over conventional V/P scans in terms of sensitivity and specificity. After radiochemical and animal studies, the clinical applicability of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was investigated in an exploratory study in patients with clinical suspicion of PE. PET scans were acquired using a 16-slice Gemini TF positron emission tomography/computed tomography (PET/CT) scanner. The acquisition protocol included low-dose computed tomography (CT) for attenuation correction (AC). Dosimetry calculations and continuative phantom measurements were performed. Structural analyses showed no modification of the particles due to the labeling process. In addition, in vitro experiments showed stability of Ga-68 MAA in various media. As expected, Ga-68-labeled human serum albumin microspheres (HSAM) were completely retained in the lung of the animals. In clinical use, PET lung ventilation and perfusion imaging using Ga-68 aerosol (Galligas) and Ga-68-labeled MAA was successful in all cases. In one case a clinically suspected PE could be detected and verified. The administered activity of Ga-68 aerosol (Galligas) and Ga-68-labeled MAA may be reduced by more than 50%, resulting in comparable radiation exposure to conventional V/P scans. In conclusion, Ga-68 aerosol (Galligas) and Ga-68-labeled MAA are efficient substitutes for clinical use and could be an interesting alternative with high accuracy for lung V/P imaging with Tc-99m-labeled radiotracers, especially in times of Mo-99 shortages and increasing use and spread of PET/CT scanners and Ga-68 generators, respectively.

Application of local anesthesia inhibits effects of low-energy extracorporeal shock wave treatment (ESWT) on nociceptors.

OBJECTIVE: Clinical studies of extracorporeal shock wave therapy (ESWT) provided conflicting results depending on the use of local anesthesia (LA). DESIGN: The present study investigated whether the biological effects of ESWT differ between application with and without LA. SETTING AND PATIENTS: In 20 healthy subjects, ESWT was applied to the ventral surface of forearm skin, either after topical lidocaine pretreatment or without on the corresponding contralateral side. MEASURES: During and after ESWT ongoing pain, axon-reflex vasodilation (laser Doppler imaging), thresholds for pinprick, and blunt pressure were recorded. RESULTS: The results indicate that increasing ESWT energy flux density led to increasing pain (P < 0.001). LA reduced ESWT-related pain (P < 0.02) and in parallel inhibited local axon-reflex vasodilation (P < 0.001). In addition, LA prevented ESWT-related drop in pressure pain threshold (P < 0.001). CONCLUSION: This study provided evidence that ESWT dose-dependently activates and sensitizes primary afferent nociceptive C-fibers, and that both activation and sensitization were prevented if LA was applied locally. These results suggest that LA substantially alters the biological responses of ESWT.