Octreo-SPECT/CT imaging for accurate detection and localization of suspected neuroendocrine tumors.
OBJECTIVE
The aim of the present study was to prospectively evaluate the add value provided by [(111)In]DTPA-octreotide single-photon emission computed tomography/computed tomography (Octreo-SPECT/CT) with respect to [(111)In]DTPA-octreotide SPECT (Octreo-SPECT) in terms of diagnostic accuracy and localization of neuroendocrine tumors (NETs).


METHODS
Eighty-one consecutive patients with known or suspected NET underwent [(111)In]DTPA-octreotide scintigraphy using an integrated SPECT/low-energy-CT system (Infinia & Hawkeye; GE Medical Systems, Milwaukee, WI, USA). SPECT and fused SPECT/CT images were interpreted separately and a lesion-by-lesion analysis was performed with regard to classification (probability of NET graded on a 5-point scale) and localization of each abnormal focal tracer uptake. A subgroup analysis, distinguishing between abdominal and thoracic lesions, and a patient-by-patient analysis for likelihood of NET in each patient was also performed. Standard of reference for confirming presence or absence of NET was either histopathology or clinical/imaging follow-up data. The value of SPECT/CT imaging was assessed by ROC analysis and McNemar test.


RESULTS
A final diagnosis of NET was achieved in 43 out of 81 patients and a total of 169 areas (138 NET and 31 benign/physiological) with focal tracer uptake were included in the final lesion-by-lesion analysis. SPECT/CT imaging led to a significantly higher proportion of patients (75/81=92.6% vs 64/81=79%) and lesions (163/169=96.4% vs 138/169=81.1%) correctly classified vs SPECT alone. ROC analysis confirmed that Octreo-SPECT/CT performed significantly better than Octreo-SPECT for the detection of NET on both patient- and lesion-based analysis, improving especially evaluation of abnormal tracer uptake in the abdomen. Moreover, Octreo-SPECT/CT accurately localized 160/169 (94.7%) lesions, significantly higher than SPECT alone (77/169= 45.6%).


CONCLUSIONS
Octreo-SPECT/CT allows more accurate detection and localization of NETs than simple Octreo-SPECT, with major benefits for lesions located in the abdomen.
Perri
M
M
Regional Center of Nuclear Medicine, University of Pisa Medical School, Pisa, Italy. marzioperri@hotmail.com
Erba
P
P
Volterrani
D
D
Lazzeri
E
E
Boni
G
G
Grosso
M
M
Mariani
G
G
D000005:Abdomen / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000000981:diagnostic imaging* / Q000473:pathology; D015282:Octreotide / Q000008:administration & dosage / Q000031:analogs & derivatives*; D010235:Paraganglioma / Q000000981:diagnostic imaging / Q000473:pathology; D004369:Pentetic Acid / Q000008:administration & dosage / Q000031:analogs & derivatives*; D012372:ROC Curve; D011860:Radiography, Abdominal; D013902:Radiography, Thoracic; D012008:Recurrence; D012680:Sensitivity and Specificity; D013909:Thorax / Q000000981:diagnostic imaging / Q000473:pathology; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed
C071632:SDZ 215-811; D004369:Pentetic Acid; D015282:Octreotide