Several studies highlighted the role of vascular 18F-NaF uptake as a marker of ongoing calcium deposition. However, 18F-NaF accumulation often shows inconsistent co-localization with arterial plaque. Actually, calcification activity and thus 18F-NaF uptake could prevail in the earlier plaque stages. To test this hypothesis, we evaluated18F-NaF uptake in three plaque types using plaque density as a marker of calcification progression. We also tested whether attenuation weighted image reconstruction affected 18F-NaF uptake values in the different plaque stages considered. METHODS: 64 oncologic patients (14 males, mean age 65.3±8.2 range 26-81) underwent 18F-NaF PET/CT. A volume of interest (VOI), was drawn on each plaque within the infra-renal aorta, to assess mean SUV and attenuation value (HU). Plaques were then divided in light (LP, HU <210), medium (MP, HU 211 to 510) and heavy (HP, HU >510). SUV was normalized for blood 18F-NaF activity, to obtain plaque target-to background ratio (TBR). In this process, several focal, non-calcified 18F-NaF uptake areas were identified (hot spots, HS). TBR was computed in HS, after iso-contour thresholding. TBR was also calculated in a non-calcified control region (CR). In 35 patients, TBR was furthermore calculated on non-attenuation-corrected (NAC) images. RESULTS: Among plaques, average TBR was highest in LP (2.21±0.88), while it was significantly lower in MP (1.59±0.53, p<0.001) and further decreased in HP (1.14±0.37, p<0.0001 with respect to both LP and MP). CR TBR was not significantly different to the one of HP and MP (P = ns), while it was significantly lower than LP and MP (p<0.01). HS had the highest absolute TBR (3.89±1.87, p<0.0001 vs LP). Considering TBR values originated from NAC didn't provide significant difference from AC. CONCLUSION: The present study is in keeping with the concept that 18F-NaF is a feasible option in imaging molecular calcium deposition in the early stages of plaque formation, when active uptake mechanism are the main determinants of calcium presence while its retention progressively decreases with increasing calcium deposition in the arterial wall. From a technical point of view, our data suggest that NAC reconstruction doesn't significantly affect output when evaluating plaques of any thickness. METHODS: 64 oncologic patients (14 males, mean age 65.3±8.2 range 26-81) underwent 18F-NaF PET/CT. A volume of interest (VOI), was drawn on each plaque within the infra-renal aorta, to assess mean SUV and attenuation value (HU). Plaques were then divided in light (LP, HU <210), medium (MP, HU 211 to 510) and heavy (HP, HU >510). SUV was normalized for blood 18F-NaF activity, to obtain plaque target-to background ratio (TBR). In this process, several focal, non-calcified 18F-NaF uptake areas were identified (hot spots, HS). TBR was computed in HS, after iso-contour thresholding. TBR was also calculated in a non-calcified control region (CR). In 35 patients, TBR was furthermore calculated on non-attenuation-corrected (NAC) images. RESULTS: Among plaques, average TBR was highest in LP (2.21±0.88), while it was significantly lower in MP (1.59±0.53, p<0.001) and further decreased in HP (1.14±0.37, p<0.0001 with respect to both LP and MP). CR TBR was not significantly different to the one of HP and MP (P = ns), while it was significantly lower than LP and MP (p<0.01). HS had the highest absolute TBR (3.89±1.87, p<0.0001 vs LP). Considering TBR values originated from NAC didn't provide significant difference from AC. CONCLUSION: The present study is in keeping with the concept that 18F-NaF is a feasible option in imaging molecular calcium deposition in the early stages of plaque formation, when active uptake mechanism are the main determinants of calcium presence while its retention progressively decreases with increasing calcium deposition in the arterial wall. From a technical point of view, our data suggest that NAC reconstruction doesn't significantly affect output when evaluating plaques of any thickness
18F-NaF uptake by the atherosclerotic plaque at PET/CT imaging: inverse correlation between calcification density and mineral metabolic activity.
Cecilia Marini;
2015
Abstract
Several studies highlighted the role of vascular 18F-NaF uptake as a marker of ongoing calcium deposition. However, 18F-NaF accumulation often shows inconsistent co-localization with arterial plaque. Actually, calcification activity and thus 18F-NaF uptake could prevail in the earlier plaque stages. To test this hypothesis, we evaluated18F-NaF uptake in three plaque types using plaque density as a marker of calcification progression. We also tested whether attenuation weighted image reconstruction affected 18F-NaF uptake values in the different plaque stages considered. METHODS: 64 oncologic patients (14 males, mean age 65.3±8.2 range 26-81) underwent 18F-NaF PET/CT. A volume of interest (VOI), was drawn on each plaque within the infra-renal aorta, to assess mean SUV and attenuation value (HU). Plaques were then divided in light (LP, HU <210), medium (MP, HU 211 to 510) and heavy (HP, HU >510). SUV was normalized for blood 18F-NaF activity, to obtain plaque target-to background ratio (TBR). In this process, several focal, non-calcified 18F-NaF uptake areas were identified (hot spots, HS). TBR was computed in HS, after iso-contour thresholding. TBR was also calculated in a non-calcified control region (CR). In 35 patients, TBR was furthermore calculated on non-attenuation-corrected (NAC) images. RESULTS: Among plaques, average TBR was highest in LP (2.21±0.88), while it was significantly lower in MP (1.59±0.53, p<0.001) and further decreased in HP (1.14±0.37, p<0.0001 with respect to both LP and MP). CR TBR was not significantly different to the one of HP and MP (P = ns), while it was significantly lower than LP and MP (p<0.01). HS had the highest absolute TBR (3.89±1.87, p<0.0001 vs LP). Considering TBR values originated from NAC didn't provide significant difference from AC. CONCLUSION: The present study is in keeping with the concept that 18F-NaF is a feasible option in imaging molecular calcium deposition in the early stages of plaque formation, when active uptake mechanism are the main determinants of calcium presence while its retention progressively decreases with increasing calcium deposition in the arterial wall. From a technical point of view, our data suggest that NAC reconstruction doesn't significantly affect output when evaluating plaques of any thickness. METHODS: 64 oncologic patients (14 males, mean age 65.3±8.2 range 26-81) underwent 18F-NaF PET/CT. A volume of interest (VOI), was drawn on each plaque within the infra-renal aorta, to assess mean SUV and attenuation value (HU). Plaques were then divided in light (LP, HU <210), medium (MP, HU 211 to 510) and heavy (HP, HU >510). SUV was normalized for blood 18F-NaF activity, to obtain plaque target-to background ratio (TBR). In this process, several focal, non-calcified 18F-NaF uptake areas were identified (hot spots, HS). TBR was computed in HS, after iso-contour thresholding. TBR was also calculated in a non-calcified control region (CR). In 35 patients, TBR was furthermore calculated on non-attenuation-corrected (NAC) images. RESULTS: Among plaques, average TBR was highest in LP (2.21±0.88), while it was significantly lower in MP (1.59±0.53, p<0.001) and further decreased in HP (1.14±0.37, p<0.0001 with respect to both LP and MP). CR TBR was not significantly different to the one of HP and MP (P = ns), while it was significantly lower than LP and MP (p<0.01). HS had the highest absolute TBR (3.89±1.87, p<0.0001 vs LP). Considering TBR values originated from NAC didn't provide significant difference from AC. CONCLUSION: The present study is in keeping with the concept that 18F-NaF is a feasible option in imaging molecular calcium deposition in the early stages of plaque formation, when active uptake mechanism are the main determinants of calcium presence while its retention progressively decreases with increasing calcium deposition in the arterial wall. From a technical point of view, our data suggest that NAC reconstruction doesn't significantly affect output when evaluating plaques of any thicknessI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
