Evaluation of ocular tumors with technetium-99m-MIBI: planar pinhole technique or SPECT?
OBJECTIVE
This study compares 2 imaging protocols, planar pinhole technique (PPHT) and SPECT, for evaluating ocular masses with 99mTc-MIBI.


METHODS
Sixteen patients with ocular lesions were studied. Planar images were acquired 10 min after the injection of 740 MBq 99mTc-MIBI with an LFOV camera fitted with a pinhole collimator (5.0 mm). A SPECT study was performed immediately after the planar study, using a 360 degrees orbit, 64 steps, 20 s/stop, a 128 x 128 matrix, and a low-energy high-resolution (LEHR) collimator. Twelve lesions (9.5-18.0 mm) proved to be malignant: 8 primary tumors (ocular melanoma); 3 local relapses of different tumors of the conjunctiva; and 1 ocular metastasis from breast cancer. The remaining 4 lesions (10.0-16.0 mm) were benign: 1 inflammatory lesion; 1 benign intraocular calcification; and 2 naevi.


RESULTS
SPECT images showed 11 of 12 malignant lesions (91.6%), whereas the planar technique demonstrated only 4 of the 12 lesions (33.3%). One false-positive result, the inflammatory lesion, was visualized by both techniques. The remaining benign lesions were not detected with either method.


CONCLUSIONS
Technetium-99m-MIBI SPECT is a sensitive technique for detecting malignant ocular tumors. SPECT imaging is a better alternative to planar imaging for ocular tumors.
Alonso
O
O
Nuclear Medicine Center of the Clinical Hospital and School of Medical Technology, University of Uruguay, Montevideo. oalonso@hc.edu.uy
Núñez
M
M
Cánepa
J
J
Guisoli
P
P
Mut
F
F
Lago
G
G
Touya
E
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology; D002114:Calcinosis / Q000000981:diagnostic imaging; D003230:Conjunctival Neoplasms / Q000000981:diagnostic imaging; D004867:Equipment Design; D005128:Eye Diseases / Q000000981:diagnostic imaging; D005134:Eye Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D005189:False Positive Reactions; D005260:Female; D015902:Gamma Cameras; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D009506:Nevus / Q000000981:diagnostic imaging; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D017256:Technetium Tc 99m Sestamibi; D014055:Tomography, Emission-Computed / Q000295:instrumentation / Q000379:methods; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods; D014605:Uveitis / Q000000981:diagnostic imaging
D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi