Technetium-99m depreotide imaging by single photon emission tomography/low resolution computed tomography in malignant lymphomas: comparison with gallium-67 citrate.
OBJECTIVE
Previous studies have demonstrated the feasibility of targeting lymphoma lesions with somatostatin receptor binding agents, mainly with In-111-pentetreotide. In the present work another somatostatin analog, Tc-99m depreotide, is investigated.


METHODS
One-hundred and six patients, 47 with Hodgkin's (HL) and 59 with various types of non-Hodgkin's lymphoma (NHL), were imaged with both Tc-99m depreotide and Ga-67 citrate. Planar whole-body and single photon emission tomography/low resolution computerized tomography (SPECT/CT) images were obtained. A total of 142 examinations were undertaken at different phases of the disease. Depreotide and gallium findings were compared visually and semi-quantitatively, with reference to the results of conventional work-up and the patients' follow-up data.


RESULTS
In most HL, intermediate- and low-grade B-cell, as well as in T-cell NHL, depreotide depicted more lesions than Ga-67 and/or exhibited higher tumor uptake. The opposite was true in aggressive B-cell NHL. However, there were notable exceptions in all lymphoma subtypes. During initial staging, 93.3% of affected lymph nodes above the diaphragm, 100% of inguinal nodes and all cases with splenic infiltration were detected by depreotide. On the basis of depreotide findings, 32% of patients with early-stage HL were upstaged. However, advanced HL and NHL cases were frequently downstaged, due to low sensitivity for abdominal lymph node (22.7%), liver (45.5%) and bone marrow involvement (36.4%). Post-therapy, depreotide detected 94.7% of cases with refractory disease or recurrence. Its overall specificity was moderate (57.1%). Rebound thymic hyperplasia, various inflammatory processes and sites of unspecific uptake were the commonest causes of false positive findings. The combination of depreotide and gallium enhanced sensitivity (100%), while various false positive results of either agent could be avoided.


CONCLUSIONS
Except perhaps for early-stage HL, Tc-99m depreotide as a stand-alone imaging modality has limited value for the initial staging of lymphomas. Post-therapy, however, depreotide scintigraphy seems useful in the evaluation of certain anatomic areas, particularly in non-aggressive lymphoma types. The combination with Ga-67 potentially enhances sensitivity and specificity. If fluorodeoxyglucose positron emission tomography is not available or in case of certain indolent lymphoma types, Tc-99m depreotide may have a role as an adjunct to conventional imaging procedures.
Apostolopoulos
Dimitris J
DJ
Department of Nuclear Medicine, University of Patras Medical School, University Hospital of Patras, Rion, Patras, Greece. dimap@med.upatras.gr
Papandrianos
Nikolaos I
NI
Symeonidis
Argiris
A
Spyridonidis
Tryfon
T
Alexiou
Sotiria
S
Zampakis
Petros
P
Savvopoulos
Christos
C
Vassilakos
Pavlos J
PJ
Matsouka
Panagiota
P
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001692:Biological Transport; D002951:Citrates; D005260:Female; D005708:Gallium; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000378:metabolism; D008223:Lymphoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015609:Organotechnetium Compounds / Q000493:pharmacokinetics; D012008:Recurrence; D013004:Somatostatin / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
D002951:Citrates; D015609:Organotechnetium Compounds; D013004:Somatostatin; C444119:technetium Tc 99m depreotide; D005708:Gallium; C103850:gallium citrate