Age-related changes in skull uptake on bone scintigraphy: a quantitative study.
BACKGROUND
"Hot skull", or diffuse increased activity of bone seeking radiotracers, is frequently seen in the bone scans of some patients, especially elderly women. This finding has been attributed to enhanced bone metabolism in old age.


METHODS
We semi-quantitatively studied 342 normal bone scans (161 male and 181 female within the age range 12 to 82 years). We divided the patients into 7 age groups: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70 and above. The geometric means of the anterior and posterior background corrected skull and mid-femoral ROI values were used for calculation of the skull to femoral ratio (SFR).


RESULTS
The skull to femoral ratio was significantly higher in female patients in the age groups 30-39 and above. In females, the five upper age groups (30-39, 40-49, 50-59, 60-69, and 70 and above) had significantly higher SFR than the lower age groups. In males, the two upper age groups (60-69, 70 and above) had significantly higher SFR than the lower age groups. The findings in males were not concordant with the previous studies addressing this issue, which could be explained by different bone mineral density in the Iranian population.


CONCLUSIONS
Our data showed that "hot skull" is not necessarily an abnormal finding, especially in elderly women. We suggest that every nuclear medicine department uses its own normal values and reference samples for quantitative evaluation, due to ethnic or socio-economical variations.
Sadeghi
Ramin
R
Nuclear Medicine Department, Mashhad University of Medical Sciences, Mashhad, Iran.
Zakavi
Seyed Rasoul
SR
Ghasemov
Masrour
M
Kakhki
Vahid Reza Dabbagh
VR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012886:Skull / Q000000981:diagnostic imaging* / Q000378:metabolism*; D013669:Technetium Tc 99m Medronate / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D055815:Young Adult
D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate