[Fusion of SPECT with computed tomography or magnetic resonance for the interpretation of abnormal tracer uptake].
BACKGROUND
Interpretation of abnormal foci with high tracer uptake may require morphological correlation. Fusion of functional images obtained by single photon emission computed tomography (SPECT) and anatomical images obtained by computed tomography (CT) or magnetic resonance (RM) allows an integrated comprehension of complementary information.


OBJECTIVE
To demonstrate that SPECT/CT fusion with external markers is useful in clinical practice to clarify the location and pathological meaning of questionable foci.


METHODS
Thirty four pairs of images from separate equipments (31 SPECT/CT and 3 SPECT/RM) pertaining to 29 patients, were fused. Fifty one foci of abnormal tracer uptake of uncertain pathological meaning were analyzed. These were classified before and after the fusion as probably malignant or probably benign.


RESULTS
Seventy percent of patients had a differentiated thyroid carcinoma. The fusion localized 100% of foci. Nine percent had a normal and 26% an abnormal anatomy. Before fusion 82% of foci were classified as potentially malignant. This figure changed to 59% after the fusion (p <0.01). Therefore the suspicion of malignancy was presumptively confirmed in 72% of foci and fusion results would have reached a 27% of incremental diagnostic value in 14 cases that changed of category (11 with differentiated thyroid carcinoma, one with colorectal cancer, one with a nasal Ewing sarcoma and one with a brain tumor).


CONCLUSIONS
The fusion of SPECT and CT is useful in selected patients, specially those with differentiated thyroid carcinoma. The fusion of SPECT and RM is also feasible.
Aqueveque A
Carolina
C
Sección Medicina Nuclear, Departamento de Medicina, Hospital Clínico, Universidad de Chile.
González E
Patricio
P
Gutiérrez B
Daniela
D
Jaimovich F
Rodrigo
R
Díaz P
Juan Carlos
JC
Csendes G
Paula
P
Orellana P
Patricia
P
Lavados M
Hugo
H
Alliende G
Isabel
I
Araya L
Sandra
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007457:Iodine Radioisotopes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013382:Subtraction Technique; D013669:Technetium Tc 99m Medronate; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D013669:Technetium Tc 99m Medronate