99mTc-HMPAO-leukocyte scintigraphy in patients with symptomatic total hip or knee arthroplasty: improved diagnostic accuracy by means of semiquantitative evaluation.
The aim of this study was to evaluate the diagnostic value, in suspected infectious prostheses, of (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) leukocyte scintigraphy interpreted with the addition of a semiquantitative analysis.


METHODS
By means of a retrospective review, we included a group of 78 consecutive patients with suspected hip or knee prosthesis infection. We performed 91 (99m)Tc-HMPAO-leukocyte scintigraphies and examined 95 localizations that were suspect. Images were acquired at 3 different time points after the injection of the labeled leukocytes: 50 min (early images), 4 h, and 24 h (late images). The scintigraphic examinations were independently evaluated by 3 observers; qualitative and semiquantitative analyses were performed. The final diagnosis of infection was based on surgical, histologic, and bacteriologic data and follow-up.


RESULTS
On qualitative analysis, sensitivity, specificity, and accuracy were 80.4%-87%, 65.3%-71.4%, and 75.8%-77.9%, respectively. On semiquantitative analysis, sensitivity, specificity, and accuracy were 95.6%, 95.8%, and 95.8%, respectively. The analysis of 95% confidential intervals showed statistically significant differences in specificity and accuracy between semiquantitative and qualitative analyses.


CONCLUSIONS
In those patients who underwent (99m)Tc-HMPAO-leukocyte scintigraphy for suspected hip or knee prosthesis infection, the addition of a semiquantitative evaluation to the qualitative analysis of early and late images leads to a significant improvement in both specificity and accuracy.
Dottorato di Ricerca Radioimmunolocalizzazione dei Tumori Umani, Università di Torino, Torino, Italy.
Ettore
E
Pelosi
Cinzia
C
Baiocco
Michele
M
Pennone
Giuseppe
G
Migliaretti
Teresio
T
Varetto
Agostino
A
Maiello
Marilena
M
Bellò
Gianni
G
Bisi
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007720:Knee Prosthesis / Q000009:adverse effects*; D007962:Leukocytes / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000209:etiology*; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019690:Technetium Tc 99m Exametazime
D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime