Gallium-67 scintigraphy: a cornerstone in functional imaging of lymphoma

In Vivo Trafficking of the Anticancer Drug Tris(8-Quinolinolato) Gallium (III) (KP46) by Gallium-68/67 PET/SPECT Imaging

KP46 (tris(hydroxyquinolinato)gallium(III)) is an experimental, orally administered anticancer drug. Its absorption, delivery to tumours, and mode of action are poorly understood. We aimed to gain insight into these issues using gallium-67 and gallium-68 as radiotracers with SPECT and PET imaging in mice. [67Ga]KP46 and [68Ga]KP46, compared with [68Ga]gallium acetate, were used for logP measurements, in vitro cell uptake studies in A375 melanoma cells, and in vivo imaging in mice bearing A375 tumour xenografts up to 48 h after intravenous (tracer level) and oral (tracer and bulk) administration. 68Ga was more efficiently accumulated in A375 cells in vitro when presented as [68Ga]KP46 than as [68Ga]gallium acetate, but the reverse was observed when intravenously administered in vivo. After oral administration of [68/67Ga]KP46, absorption of 68Ga and 67Ga from the GI tract and delivery to tumours were poor, with the majority excreted in faeces. By 48 h, low but measurable amounts were accumulated in tumours. The distribution in tissues of absorbed radiogallium and octanol extraction of tissues suggested trafficking as free gallium rather than as KP46. We conclude that KP46 likely acts as a slow releaser of gallium ions which are inefficiently absorbed from the GI tract and trafficked to tissues, including tumour and bone.

Non-invasive radionuclide imaging of trace metal trafficking in health and disease: "PET metallomics"

Several specific metallic elements must be present in the human body to maintain health and function. Maintaining the correct quantity (from trace to bulk) and location at the cell and tissue level is essential. The study of the biological role of metals has become known as metallomics. While quantities of metals in cells and tissues can be readily measured in biopsy and autopsy samples by destructive analytical techniques, their trafficking and its role in health and disease are poorly understood. Molecular imaging with radionuclides - positron emission tomography (PET) and single photon emission computed tomography (SPECT) - is emerging as a means to non-invasively study the acute trafficking of essential metals between organs, non-invasively and in real time, in health and disease. PET scanners are increasingly widely available in hospitals, and methods for producing radionuclides of some of the key essential metals are developing fast. This review summarises recent developments in radionuclide imaging technology that permit such investigations, describes the radiological and physicochemical properties of key radioisotopes of essential trace metals and useful analogues, and introduces current and potential future applications in preclinical and clinical investigations to study the biology of essential trace metals in health and disease.

In situ lymphoma imaging in a spontaneous mouse model using the Cerenkov Luminescence of F-18 and Ga-67 isotopes

Cerenkov luminescence imaging (CLI) is a promising approach to image-guided surgery and pathological sampling. It could offer additional advantages when combined to whole-body isotope tomographies. We aimed to obtain evidence of its applicability in lymphoma patho-diagnostics, thus we decided to investigate the radiodiagnostic potential of combined PET or SPECT/CLI in an experimental, novel spontaneous high-grade B-cell lymphoma mouse model (Bc.DLFL1). We monitored the lymphoma dissemination at early stage, and at clinically relevant stages such as advanced stage and terminal stage with in vivo 2-deoxy-2-[¹⁸F]fluoro-d-glucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) and ⁶⁷Ga-citrate single photon emission computed tomography (SPECT)/MRI. In vivo imaging was combined with ex vivo high resolution CLI. The use of CLI with ¹⁸F-Fluorine (F-18) and ⁶⁷Ga-Gallium isotopes in the selection of infiltrated lymph nodes for tumor staging and pathology was thus tested. At advanced stage, FDG PET/MRI plus ex vivo CLI allowed accurate detection of FDG accumulation in lymphoma-infiltrated tissues. At terminal stage we detected tumorous lymph nodes with SPECT/MRI and we could report in vivo detection of the Cerenkov light emission of ⁶⁷Ga. CLI with ⁶⁷Ga-citrate revealed lymphoma accumulation in distant lymph node locations, unnoticeable with only MRI. Flow cytometry and immunohistochemistry confirmed these imaging results. Our study promotes the combined use of PET and CLI in preclinical studies and clinical practice. Heterogeneous FDG distribution in lymph nodes, detected at sampling surgery, has implications for tissue pathology processing and it could direct therapy. The results with ⁶⁷Ga also point to the opportunities to further apply suitable SPECT radiopharmaceuticals for CLI.

Calculations for the nuclear reaction cross-sections via α-particle induced reactions on 65Cu to produce impurity free 67Ga for medical applications

Diagnostics field is facilitated with advancements enacted in anatomic imaging (cross-sectional modalities). Radionuclide scans (imaging) escorted by ⁶⁷Ga are extensively beneficial in bone scintigraphy and recognition of prosthetic joint failure. Present work comprises the data concerning ⁶⁷Ga production via α-particle induced nuclear reactions, TTY (thick target yield) and impurity analysis. Experimental measurements regarding ⁶⁷Ga production are analyzed through a comparative study performed with calculations of theoretical model codes (TALYS-1.95, EMPIRE-3.2.3 and ALICE-IPPE). A data set of recommended cross-sections was generated and utilized to deduce TTY. The contribution of radionuclidic impurities is canvassed to suggest an energy region to produce impurity free ⁶⁷Ga for medical applications.

Applying standardized uptake values in gallium-67-citrate single-photon emission computed tomography/computed tomography studies and their correlation with blood test results in representative organs

OBJECTIVES

Recently, semiquantitative analysis using standardized uptake value (SUV) has been introduced in bone single-photon emission computed tomography/computed tomography (SPECT/CT). Our purposes were to apply SUV-based semiquantitative analytic method for gallium-67 (Ga)-citrate SPECT/CT and to evaluate correlation between SUV of physiological uptake and blood test results in representative organs.

METHODS

The accuracy of semiquantitative method was validated using an National Electrical Manufacturers Association body phantom study (radioactivity ratio of sphere : background=4 : 1). Thereafter, 59 patients (34 male and 25 female; mean age, 66.9 years) who had undergone Ga-citrate SPECT/CT were retrospectively enrolled in the study. A mean SUV of physiological uptake was calculated for the following organs: the lungs, right atrium, liver, kidneys, spleen, gluteal muscles, and bone marrow. The correlation between physiological uptakes and blood test results was evaluated using Pearson's correlation coefficient.

RESULTS

The phantom study revealed only 1% error between theoretical and actual SUVs in the background, suggesting the sufficient accuracy of scatter and attenuation corrections. However, a partial volume effect could not be overlooked, particularly in small spheres with a diameter of less than 28 mm. The highest mean SUV was observed in the liver (range: 0.44-4.64), followed by bone marrow (range: 0.33-3.60), spleen (range: 0.52-2.12), and kidneys (range: 0.42-1.45). There was no significant correlation between hepatic uptake and liver function, renal uptake and renal function, or bone marrow uptake and blood cell count (P>0.05).

CONCLUSION

The physiological uptake in Ga-citrate SPECT/CT can be represented as SUVs, which are not significantly correlated with corresponding blood test results.

Image-guided radiation therapy in lymphoma management

Image-guided radiation therapy (IGRT) is a process of incorporating imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), Positron emission tomography (PET), and ultrasound (US) during radiation therapy (RT) to improve treatment accuracy. It allows real-time or near real-time visualization of anatomical information to ensure that the target is in its position as planned. In addition, changes in tumor volume and location due to organ motion during treatment can be also compensated. IGRT has been gaining popularity and acceptance rapidly in RT over the past 10 years, and many published data have been reported on prostate, bladder, head and neck, and gastrointestinal cancers. However, the role of IGRT in lymphoma management is not well defined as there are only very limited published data currently available. The scope of this paper is to review the current use of IGRT in the management of lymphoma. The technical and clinical aspects of IGRT, lymphoma imaging studies, the current role of IGRT in lymphoma management and future directions will be discussed.

A nuclear chocolate box: the periodic table of nuclear medicine

Radioisotopes of elements from all parts of the periodic table find both clinical and research applications in radionuclide molecular imaging and therapy (nuclear medicine). This article provides an overview of these applications in relation to both the radiological properties of the radionuclides and the chemical properties of the elements, indicating past successes, current applications and future opportunities and challenges for inorganic chemistry.

Positron emission tomography: clinical applications in oncology. Part 1

Positron emission tomography is a functional diagnostic imaging technique, which can accurately measure in vivo distribution of a radiopharmaceutical with high resolution. The ability of positron emission tomography to study various biologic processes opens up new possibilities for both research and day-to-day clinical use. Positron emission tomography has progressed rapidly from being a research technique in laboratories to a routine clinical imaging modality becoming part of armamentarium for the medical profession. The most widely used radiotracer in positron emission tomography is 18F-fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. FDG uptake in cells is directly proportional to glucose metabolism of cells. Since glucose metabolism is increased many fold in malignant tumors, positron emission tomography has a high sensitivity and high negative predictive value. Positron emission tomography with FDG is now the standard of care in initial staging, monitoring the response to therapy and management of lung cancer, colorectal cancer, lymphoma, melanoma, esophageal cancer, head and neck cancer and breast cancer. The aim of this article is to review the clinical applications of positron emission tomography in oncology.

Is there still a role for SPECT-CT in oncology in the PET-CT era?

For the evaluation of biological processes using radioisotopes, there are two competing technologies: single-photon emission computed tomography (SPECT) and positron emission tomography (PET). Both are tomographic techniques that enable 3D localization and can be combined with CT for hybrid imaging. PET-CT has clear technical superiority including superior resolution, speed and quantitative capability. SPECT-CT currently has greater accessibility, lower cost and availability of a wider range of approved radiotracers. However, the past decade has seen dramatic growth in PET-CT with decreasing costs and development of an increasing array of PET tracers that can substitute existing SPECT applications. PET-CT is also changing the paradigm of imaging from lesion measurement to lesion characterization and target quantification, supporting a new era of personalized cancer therapy. The efficiency and cost savings associated with improved diagnosis and clinical decision-making provided by PET-CT make a cogent argument for it becoming the dominant molecular technique in oncology.

Positron emission tomography imaging of tumor angiogenesis with a 66Ga-labeled monoclonal antibody

The goal of this study was to develop a (66)Ga-based positron emission tomography (PET) tracer for noninvasive imaging of CD105 expression during tumor angiogenesis, a hallmark of cancer. (66)Ga was produced using a cyclotron with (nat)Zn or isotopically enriched (66)Zn targets. TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) and labeled with (66)Ga. No difference in CD105 binding affinity or specificity was observed between TRC105 and NOTA-TRC105 based on flow cytometry analysis. Reactivity of (66)Ga for NOTA, corrected to the end of bombardment, was between 74 and 222 GBq/μmol for both target enrichments with <2 ppb of cold gallium. (66)Ga-labeling was achieved with >80% radiochemical yield. Serial PET imaging revealed that the murine breast cancer 4T1 tumor uptake of (66)Ga-NOTA-TRC105 was 5.9 ± 1.6, 8.5 ± 0.6, and 9.0 ± 0.6% ID/g at 4, 20, and 36 h postinjection, respectively (n = 4). At the last time point, tumor uptake was higher than that of all organs, which gave excellent tumor contrast with a tumor/muscle ratio of 10.1 ± 1.1. Biodistribution data as measured by gamma counting were consistent with the PET findings. Blocking experiment, control studies with (66)Ga-NOTA-cetuximab, as well as ex vivo histology all confirmed the in vivo target specificity of (66)Ga-NOTA-TRC105. Successful PET imaging with high specific activity (66)Ga (>700 GBq/μmol has been achieved) as the radiolabel opens many new possibilities for future PET research with antibodies or other targeting ligands.

18-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in the Management of Aggressive Non-Hodgkin's B-Cell Lymphoma

18-Fluorodeoxyglucose (FDG-PET/CT) is an established imaging modality that has been proven to be of benefit in the management of aggressive B-cell non-Hodgkin's lymphoma, such as diffuse large B-cell lymphoma and advanced stage follicular lymphoma. The combination of anatomic and functional imaging afforded by FDG-PET/CT has led to superior sensitivity and specificity in the primary staging, restaging, and assessment of response to treatment of hematological malignancies when compared to FDG-PET and CT alone. The use of FDG-PET/CT for posttreatment surveillance imaging remains controversial, and further study is needed to ascertain whether this modality is cost effective and appropriate for use in this setting.

Underperformance of gallium-67 scan is greater in relapse than in initial staging, compared with FDG PET

PURPOSE

The purpose of this study is to evaluate the performance of gallium-67 scan (GS) and F-18 fluorodeoxyglucose (FDG) PET scan in lymphoma staging and recurrence detection by comparing the 2 imaging studies in the same patient.

MATERIALS AND METHODS

A total of 42 patients from the period between July 2002 and May 2006 were included in this study. Of the 42 patients, 6 had Hodgkin disease and 36 had non-Hodgkin lymphomas. All of them underwent one or more FDG PET scans and also underwent corresponding GS performed within 7 days of FDG PET, for staging or detection of lymphoma recurrence. Among the non-Hodgkin lymphoma cases, 18 were diffuse large B-cell lymphoma, 10 were follicular center cell lymphoma, and 8 were of other types. Of the total 46 pairs of imaging performed in these 42 patients, 27 were for staging, and 19 for restaging after recurrence.

RESULTS

In all these studies, FDG PET detected 230 lesion sites, whereas GS detected 85 lesion sites. All of the lesions detected by GS were noted on FDG PET, whereas GS detected only 37.0% of the lesions detected by FDG PET. Among the 27 studies for staging, FDG PET detected 120 lesions, whereas GS detected 68 lesions (56.7%). In the 19 images taken for relapse, FDG PET detected 110 lesions, whereas GS detected only 17 (15.5%).

CONCLUSIONS

FDG PET is superior to GS in staging and detecting all types of lymphoma. The difference is notably more significant in recurrence detection.

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.

CONCLUSION

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.

Prognostic value of early 18 fluorodeoxyglucose positron emission tomography and gallium-67 scintigraphy in aggressive lymphoma: a prospective comparative study

The prognostic value of fluorodeoxyglucose positron emission tomography (FDG-PET) and gallium-67 scan (GS) performed early after chemotherapy was assessed in 40 patients with newly diagnosed aggressive lymphoma. FDG-PET and GS were performed before and after three cycles of CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) or two cycles of ACVBP (doxorubicin, cyclophosphamide, vindesine, bleomycin, prednisone), with or without rituximab. Thirty-five patients had diffuse large B-cell lymphoma (DLBCL), two had mantle-cell lymphoma and three had T-cell lymphoma. Four patients relapsed despite early negative FDG-PET and GS including all three patients with T-cell lymphoma. Nine patients stayed in remission despite positive FDG-PET and/or GS of whom five showed moderate intensity residual bone uptake. Seven of these nine early false positives had a negative exam at the end of treatment. In patients with DLBCL, the 2-year event-free survival was 85% for negative versus 30% for positive FDG-PET patients (P = 0.003) whereas it was 78% for negative versus 33% for positive GS patients (P = 0.018). Sensitivity, specificity and diagnostic accuracy of FDG-PET and GS were not significantly different: 90% versus 70%, 76 versus 80% and 80 versus 77%, respectively. We conclude that both FDG-PET and GS are valuable tools to early predict outcome in patients with DLBCL.

Hodgkin's lymphoma--patient's assessment and staging

Hodgkin's lymphoma is one of the most curable malignancies today. But treatment is associated with significant toxicity. The objective of high-quality management is to minimize treatment exposure while maximizing cure of disease. Principles of cancer staging and patient's assessment taxonomy are important to improve communication. An orderly patient evaluation and systematic recording of disease extent using the Ann Arbor classification forms the basis for treatment decision, response assessment, and clinical trials. The practice of staging in Hodgkin's lymphoma evolved over the past 40 years from clinical examination and plain imaging to modern anatomic and functional imaging. Although useful in the past, staging laparotomy, lymphangiograms, and Gallium scintigraphy have now been abandoned. Computerized tomography combined with 2-[18F]fluoro-2-deoxyglucose-positron emission tomography form the basis for anatomic disease extent assessment. Although patients' evaluation and staging at diagnosis are important, the management of Hodgkin's lymphoma involves a complex series of algorithms requiring interim and overall response assessment, careful follow-up, repeat assessment, and salvage management of recurrent disease.

A breast fibroadenoma mimicking an extranodal deposit of Hodgkin's lymphoma in 67Ga imaging

We present the case of a young woman with classical nodular sclerosing Hodgkin's lymphoma (clinical stage IIB). During staging work-up, intense gallium-67 ((67)Ga) accumulation in a left breast lump raised the suspicion of an extranodal deposit, but biopsy favoured a benign histology. A post-treatment (67)Ga scan showed complete remission of the disease with normal tracer uptake in the left breast. However, a few months after treatment, a faint left mammary concentration of (67)Ga was observed. The breast mass was excised and histopathology was consistent with fibroadenoma. This unusual presentation is a new addition to the literature on false-positive (67)Ga findings and chemotherapy-associated tracer changes.

99mTc-labelled rituximab, a new non-Hodgkin's lymphoma imaging agent: first clinical experience

OBJECTIVE

This study was performed to explore the possibility of using Tc-rituximab as an imaging agent to assess expression of CD20 antigen in patients with B-cell non-Hodgkin's lymphoma (NHL) before (radio) immunotherapy, for staging and subsequent evaluation of remission of NHL.

METHODS

Rituximab was purified from Mabthera and photoactivated by ultraviolet light. The irradiated solution was aliquoted and labelled with pertechnetate. The effectiveness of the labelling method was evaluated by determination of the number of free thiol groups per photoreduced antibody, radiochemical purity determination and in-vitro stability. Immunoreactivity of Tc-rituximab was assessed on Ramos cells using a direct binding assay. Ten patients (age 31-70 years, mean 50 years) were included, nine with CD20 B-cell NHL and one with CD20-NHL. Whole-body and single photon emission computed tomography images were taken 1, 3, 6 and 20 h postinjection of Tc-rituximab. Scintigraphic results were compared with computerized tomography (CT) findings.

RESULTS

In all cases radiochemical purity over 95% was observed with preserved affinity for CD20 antigen. In all patients expected activity was seen in the blood pool, liver, kidneys and spleen. Pathological, moderately to markedly increased Tc-rituximab activity was seen in all but one CT-confirmed NHL involved sites 6 and 20 h postinjection. In one patient, increased activity of Tc-rituximab was additionally seen in one region not seen on CT. In three patients increased accumulation was seen in bone marrow.

CONCLUSION

Tc-rituximab is a promising imaging agent suitable for assessing expression of CD20 in patients with NHL before (radio) immunotherapy.

Role of serial quantitative gallium-67 tumor uptake in assessing response rates for chemotherapy in lymphoma patients

PURPOSE

To evaluate in serial gallium-67 scans (GS) the role of semiquantitative tumor-to-background (Tm/Bg) and tumor-to-liver ratios in assessing response rates to chemotherapy, in Hodgkin's disease and non-Hodgkin's lymphoma.

MATERIALS AND METHODS

Twenty-seven consecutive patients (15 Hodgkin's disease and 12 non-Hodgkin's lymphoma patients) with an average age of 30 (range, 5-60) years underwent GS at prechemotherapy, early chemotherapy (after first cycle), and postchemotherapy. Average tumor, background, and liver region of interest counts obtained and Tm/Bg, tumor-to-liver, and liver region to background ratios were derived for each patient on serial GS. All patients were assessed by visual and quantitative GS and followed up clinically for more than 7 years.

RESULTS

At early visual GS, 70% (19 of 27) of the patients showed rapid response, 15% (four of 27) showed delayed response (negative at post-GS), and 15% showed no response. Mean early-GS Tm/Bg ratio of disease-free patients (1+/-0.04) was significantly different from relapsed (1.4+/-0.2) (P<0.025) and progressive disease (1.8+/-0.7) patients. A significant difference was noted (P<0.01) in serial paired comparisons of Tm/Bg ratios between pretherapy and early-therapy scans in relapsed patients, whereas progressive disease patients showed no significant change during the same time. At early-GS, 15 patients showed quantitative rapid response (Tm/Bg ratio 1.04), nine patients showed quantitative delayed response (Tm/Bg ratio >1.04 with significant serial change between pretherapy and early-therapy GS), and three patients showed quantitative no response (Tm/Bg ratio >1.04 with nonsignificant serial change between pretherapy and posttherapy GS).

CONCLUSION

Quantitative GS is an effective tool in the detection of early response to chemotherapy. Quantitative response rates after the first cycle can more reliably identify patients who are most likely to be disease-free or relapse after first-line therapy or those that will show no response to therapy as compared with visual analysis alone.

Technological development and advances in single-photon emission computed tomography/computed tomography

Single-photon emission computed tomography/computed tomography (SPECT/CT) has emerged during the past decade as a means of correlating anatomical information from CT with functional information from SPECT. The integration of SPECT and CT in a single imaging device facilitates anatomical localization of the radiopharmaceutical to differentiate physiological uptake from that associated with disease and patient-specific attenuation correction to improve the visual quality and quantitative accuracy of the SPECT image. The first clinically available SPECT/CT systems performed emission-transmission imaging using a dual-headed SPECT camera and a low-power x-ray CT subsystem. Newer SPECT/CT systems are available with high-power CT subsystems suitable for detailed anatomical diagnosis, including CT coronary angiography and coronary calcification that can be correlated with myocardial perfusion measurements. The high-performance CT capabilities also offer the potential to improve compensation of partial volume errors for more accurate quantitation of radionuclide measurement of myocardial blood flow and other physiological processes and for radiation dosimetry for radionuclide therapy. In addition, new SPECT technologies are being developed that significantly improve the detection efficiency and spatial resolution for radionuclide imaging of small organs including the heart, brain, and breast, and therefore may provide new capabilities for SPECT/CT imaging in these important clinical applications.

Prognostic impact of pre-transplantation computed tomography and 67gallium scanning in chemosensitive diffuse large B cell lymphoma patients undergoing hematopoietic stem-cell transplantation

OBJECTIVE

In the present study, we evaluated computed tomography (CT) and (67)gallium scanning ((67)Ga scan) pre-transplant as prognostic factors for overall survival (OS) and event-free survival (EFS) in patients with diffuse large B cell lymphoma, undergoing high-dose chemotherapy and stem-cell transplantation.

PATIENTS AND METHODS

Forty-two patients were included. Of these, 9 (21%) had both positive CT and (67)Ga scans, 17 (41%) negative results with both techniques, and 16 (38%) positive CT/negative (67)Ga scan. Whole-body planar imaging and single-photon emission computed tomography (SPECT) were performed 72 h after an intravenous administration of (67)Ga citrate measuring between 7 mCi and 10 mCi (259-370 MBq).

RESULTS

Patients with positive CT/positive (67)Ga scan had a significantly worse EFS and OS at 5 years than those with negative (67)Ga scan regardless of whether it was associated with a positive or a negative CT scan (29% and 16% vs. 81% and 93% vs. 88% and 100%, respectively, P < 0.001). After a median follow-up of 43 months (range 4-130 months), no differences were observed between patients with negative CT/negative (67)Ga scan and those with positive CT/negative (67)Ga scan, with an EFS and OS at 5 years of 88% versus 81% and 100% versus 93%, respectively. In multivariate analysis, the presence of a pre-transplant positive CT/(67)Ga scans adversely influenced both EFS and OS [HR 8, 95% confidence interval (CI) (1.4-38), P = 0.03 and HR 2; 95% CI (1.3-8), P = 0.02, respectively].

CONCLUSIONS

(67)Ga scan helps to identify, in the pre-transplant evaluation, two groups with a different outcome: one group of patients with positive CT and negative (67)Ga scans pre-transplant, who showed a favorable outcome with a low rate of relapse, and the other group of patients with both positive CT and (67)Ga scans pre-transplant, who showed a poor prognosis and did not benefit from autologous stem-cell transplantation. They should have been offered other therapeutic strategies.

The role of hybrid SPECT-CT in oncology: current and emerging clinical applications

Single photon emission computed tomography - computed tomography (SPECT-CT) is an emerging dual-modality imaging technique with many established and potential clinical applications in the field of oncology. To date, there has been a considerable emphasis on the benefits of integrated positron emission tomography - computed tomography (PET-CT) in oncology, but relatively little focus on the clinical utility of SPECT-CT. As with PET-CT, accurate co-registration of anatomical and functional data from a combined SPECT-CT camera often provides complementary diagnostic information. Both sensitivity (superior disease localization) and specificity (exclusion of false-positives due to physiological tracer uptake) are improved, and the functional significance of indeterminate lesions detected on cross-sectional imaging can be defined. This article will review the scope of hybrid SPECT-CT in oncology and illustrate both current and emerging clinical applications.

2-[18F]fluoro-2-deoxyglucose positron-emission tomography in staging, response evaluation, and treatment planning of lymphomas

2-[18F]fluoro-2-deoxyglucose positron-emission tomography (FDG-PET) is used increasingly in the clinical management of lymphomas. With regard to staging, FDG-PET is more sensitive and specific than conventional staging methods in FDG avid lymphomas (ie, Hodgkin lymphoma and most aggressive non-Hodgkin lymphomas). Despite methodological problems, in particular the lack of a valid reference test, FDG-PET is approved and generally used for this purpose. With regard to response evaluation, FDG-PET at the end of treatment seems to aid considerably in differentiating between residual masses with or without residual lymphoma. Hence, new revised response criteria have been proposed, incorporating the result of FDG-PET at the end of treatment. An early interim FDG-PET scan after 1 to 3 cycles of chemotherapy is a very strong predictor of outcome, and trials are now in progress testing treatment modifications on this basis. With regard to treatment planning, in the context of combined-modality therapy, radiotherapy for lymphomas is moving toward more conformal techniques reducing the irradiated volume to include only the macroscopic lymphoma. In this situation, accurate imaging is essential, and FDG-PET coregistered with the planning computed tomography (CT) scan is used increasingly. The availability of PET/CT scanners suited for virtual simulation has aided this process. However, clinical data evaluating this technique are at present sparse.

Overview of early response assessment in lymphoma with FDG-PET

Early assessment of response to chemotherapy with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is becoming a routine part of management in patients with Hodgkin lymphoma (HL) and histologically aggressive non-Hodgkin lymphoma (NHL). Changes in FDG uptake can occur soon after the initiation of therapy and they precede changes in tumour volume. Recent studies in uniform populations of aggressive lymphomas (predominantly diffuse large B cell lymphomas) and HL have clarified the value of early response assessment with PET. These trials show that PET imaging after 2-3 chemotherapy cycles is far superior to CT-based imaging in predicting progression-free survival and can be at least as reliable as definitive response assessment at the end of therapy. This information is of great potential value to patients, but oncologists should be cautious in the use of early PET response in determining choice of therapy until some critical questions are answered. These include: When is the best time to use PET for response assessment? What is the best methodology, visual or quantitative? (For HL at least, visual reading appears superior to an SUV-based assessment). Can early responders be cured with less intensive therapy? Will survival be better for patients treated more intensively because they have a poor interim metabolic response? In the future, early PET will be crucial in developing response-adapted therapy but without further carefully designed clinical trials, oncologists will remain uncertain how best to use this new information.

The role of FDG PET in the management of lymphoma: what is the evidence base?

[18F]Fluorodeoxyglucose positron emission tomography (18F-FDG PET) is playing an increasing role in the management of both Hodgkin and non-Hodgkin lymphoma, offering potential advantages in the accuracy of disease assessment at a number of points in the management pathway. This review evaluates the current level of confidence in the use of PET technology in (1) initial staging, (2) the assessment of early response to chemotherapy, (3) the assessment of residual masses at completion of initial treatment, (4) follow-up, and (5) radiotherapy planning.

Single-Photon Emission Computed Tomography/Computed Tomography in Lung Cancer and Malignant Lymphoma

In nuclear oncology, despite the fast-growing diffusion of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET), single-photon emission computed tomography (SPECT) studies can still play an useful clinical role in several applications. The main limitation of SPECT imaging with tumor-seeking agents is the lack of the structural delineation of the pathologic processes they detect; this drawback sometimes renders SPECT interpretation difficult and can diminish its diagnostic accuracy. Fusion with morphological studies can overcome this limitation by giving an anatomical map to scintigraphic data. In the past, software-based fusion of independently performed SPECT and CT images proved to be time-consuming and impractical for routine use. The recent development of dual-modality integrated imaging systems that provide functional (SPECT) and anatomical (CT) images in the same scanning session, with the acquired images coregistered by means of the hardware, has opened a new era in this field. The first reports indicate that SPECT/CT is very useful in cancer imaging because it is able to provide further information of clinical value in several cases. In SPECT, studies of lung cancer and malignant lymphomas using different radiopharmaceutical, hybrid images are of value in providing the correct localization of tumor sites, with a precise detection of the involved organs, and the definition of their functional status, and in allowing the exclusion of disease in sites of physiologic tracer uptake. Therefore, in lung cancer and lymphomas, hybrid SPECT/CT can play a role in the diagnosis of the primary tumor, in the staging of the disease, in the follow-up, in the monitoring of therapy, in the detection of recurrence, and in dosimetric estimations for target radionuclide therapy.

An audit of imaging test utilization for the management of lymphoma in an oncology hospital: implications for resource planning?

The purpose of this study was to assist with resource planning by examining the pattern of physician utilization of imaging procedures for lymphoma patients in a dedicated oncology hospital. The proportion of imaging tests ordered for routine follow up with no specific clinical indication was quantified, with specific attention to CT scans. A 3-month audit was performed. The reasons for ordering all imaging procedures (X-rays, CT scans, ultrasound, nuclear scan and MRI) were determined through a retrospective chart review. 411 lymphoma patients had 686 assessments (sets of imaging tests) and 981 procedures (individual imaging tests). Most procedures were CT scans (52%) and chest radiographs (30%). The most common reasons for ordering imaging were assessing response (23%), and investigating new symptoms (19%). Routine follow up constituted 21% of the assessments (142/686), and of these, 82% were chest radiographs (116/142), while 24% (34/142) were CT scans. With analysis restricted to CT scans (296 assessments in 248 patients), the most common reason for ordering CT scans were response evaluation (40%), and suspicion of recurrence and/or new symptom (23%). Follow-up CT scans done with no clinical indication comprised 8% (25/296) of all CT assessments. Staging CT scans were under-represented at 6% of all assessments. Imaging with CT scans for follow up of asymptomatic patients is infrequent. However, scans done for staging new lymphoma patients were unexpectedly low in frequency, due to scans done elsewhere prior to referral. This analysis uncovered utilization patterns, helped resource planning and provided data to reduce unnecessary imaging procedures.

Value of [18F]Fluorodeoxyglucose–Positron Emission Tomography in Managing Adults with Aggressive Non-Hodgkin's Lymphoma

An increased glucose metabolic rate is observed with various degrees of intensity in different subtypes of aggressive lymphomas. [(18)F]Fluorodeoxyglucose (FDG)-positron emission tomography (PET; FDG-PET) allows functional imaging of this phenomenon through 3-dimensional tomographic slices, which are now easily fused with computed tomography (CT) images. [(18)F]Fluorodeoxyglucose-PET staging appears superior to conventional staging modalities for detecting nodal and extranodal lymphoma. When performed after first-line chemotherapy, FDG-PET is more efficient than CT and conventional diagnostic methods to predict the disease outcome. Some studies have reported that the relapse rate is 100% in patients with positive PET findings after treatment and 17% in patients with negative PET findings. This imaging modality can also assess early response after 1-2 cycles of chemotherapy, thus identifying responders from patients whose cancer will fail to respond to first-line therapy or will relapse shortly after having exhibited a partial or complete remission. [(18)F]Fluorodeoxyglucose-PET also seems useful for an accurate selection of patients who will benefit from highly intensive treatment.

99mTc-rituximab radiolabelled by photo-activation: a new non-Hodgkin’s lymphoma imaging agent

PURPOSE

Rituximab was the first chimeric monoclonal antibody to be approved for treatment of indolent B-cell non-Hodgkin's lymphoma (NHL). It is directed against the CD20 antigen, which is expressed by 95% of B-cell NHLs. The aim of this study was to explore the possibility of radiolabelling rituximab with (99m)Tc for use as an imaging agent in NHL for early detection, staging, remission assessment, monitoring for metastatic spread and tumour recurrence, and assessment of CD20 expression prior to (radio)immunotherapy.

METHODS

Rituximab was purified from Mabthera solution (Roche), photo-activated at 302 nm by UV irradiation and radiolabelled with (99m)Tc. The effectiveness of the labelling method was evaluated by determination of the number of free thiol groups per photoreduced antibody, radiochemical purity and in vitro stability of (99m)Tc-rituximab.

RESULTS

On average, 4.4 free thiol groups per photoreduced antibody were determined. Radiolabelling yields greater than 95% were routinely observed after storage of the photo-activated antibody at -80 degrees C for 195 days. The direct binding assay showed preserved ability of (99m)Tc-rituximab to bind to CD20, with an average immunoreactive fraction of 93.3%. The internalisation rate was proven to be low, with only 5.3% of bound (99m)Tc-rituximab being internalised over 4 h at 37 degrees C.

CONCLUSION

Our results demonstrate that (99m)Tc-rituximab of high radiochemical purity and with preserved binding affinity for the antigen can be prepared by photoreduction and that the method shows good reproducibility. (99m)Tc-rituximab will be further explored as an imaging agent applicable in NHL for the purposes mentioned above.

67Ga-SPECT/CT with a hybrid system in the clinical management of lymphoma

PURPOSE

The purpose of this study was to investigate the added value of co-registered fusion imaging using a hybrid system in patients with lymphoma.

METHODS

Twenty-four lymphoma patients underwent (67)Ga-SPECT/CT using a hybrid tomograph consisting of a dual-head, variable-angle gamma camera and a low-dose X-ray tube. Results were compared with those of SPECT alone.

RESULTS

Forty-five lesions were identified by SPECT alone, while 49 were detected by SPECT/CT. Forty out of the 45 lesions observed on SPECT were confirmed as lymphoma, but five were due to other causes (thoracic aorta blood pool activity, sialoadenitis in the submandibular gland, bowel activity, rib fracture and bone marrow activation due to radiotherapy). SPECT/CT identified nine more neoplastic lesions compared with SPECT alone: four areas of radiopharmaceutical accumulation were observed in para-aortic lymph nodes, three in the spleen, one in the liver and one in para-iliac lymph nodes. In five cases, SPECT/CT provided additional anatomical information over SPECT alone. In four patients, four large areas of (67)Ga uptake (one mediastinal, two supraclavicular and one para-aortic) were better characterised; in one subject uptake was localised in the seventh thoracic vertebra only by SPECT/CT. Hybrid imaging provided additional data in 13 patients (54.2%), thus inducing oncologists to reconsider the therapeutic approach in eight subjects (33.2%): unnecessary treatment was avoided in four (16.6%) while therapy was altered in another four (16.6%).

CONCLUSION

SPECT/CT hybrid system is able to provide information not obtained by SPECT alone. It allows the anatomical localisation of lymphoma and physiological radiopharmaceutical uptake, facilitates the diagnosis of tumours located in the abdomen (subdiaphragmatic lesions) and provides information that may cause a change in therapeutic strategy.

[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in aggressive lymphoma: an early prognostic tool for predicting patient outcome

Assessment of early therapeutic response using metabolic imaging is potentially useful to determine prognosis in aggressive lymphoma. Between January 2000 and January 2004, 90 patients with newly diagnosed aggressive lymphoma (median age 53 years, 94% diffuse large B-cell) were prospectively explored with [18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) prior to induction chemotherapy, after 2 cycles ("early PET"), and after induction completion. Therapeutic response was evaluated using conventional diagnostic methods at 4 cycles. Induction treatment with an anthracycline-containing regimen was administered to all patients, associated with rituximab in 41%. According to the International Prognostic Index (IPI), 37 patients and 53 patients belonged to the lower- and higher-risk groups, respectively. At midinduction, "early PET" was considered negative in 54 patients and positive in 36. After completion of induction, 83% of PET-negative patients achieved complete remission compared with only 58% of PET-positive patients. Outcome differed significantly between PET-negative and PET-positive groups; the 2-year estimates of event-free survival reached 82% and 43%, respectively (P < .001), and the 2-year estimates of overall survival reached 90% and 61%, respectively (P = .006). Predictive value of "early PET" was observed in both the lower-risk and higher-risk groups, indicating prognostic independence from the IPI. Therefore, FDG-PET should be an early guide to first-line strategies in aggressive lymphoma.

Spontaneous Regression of Follicular, Mantle Cell, and Diffuse Large B-Cell Non-Hodgkinʼs Lymphomas Detected by FDG–PET Imaging

Spontaneous regression of non-Hodgkin lymphoma (NHL) has been reported in low-grade tumors but is an extremely rare event in intermediate- and high-grade disease. Documentation of spontaneous regression by serial fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging has not been reported in the literature. We present 3 cases of spontaneous regression, 1 each of follicular lymphoma (FL), mantle cell lymphoma (MCL), and diffuse large B-cell lymphoma (DLBCL), which showed spontaneous regression on serial FDG-PET imaging. All patients underwent serial whole-body FDG-PET scans 60 minutes after intravenous injection of 9-11 mCi of this radiotracer. None of them had any chemotherapy, radiotherapy, or surgery after the baseline PET scan. Spontaneous regression of disease in all 3 cases was correlated with conventional imaging and clinical course. All 3 patients had positive FDG-PET results on their baseline scan. There was complete disappearance of FDG uptake on a follow-up PET scan for the patient with follicular lymphoma. These results suggest complete regression. The patients with MCL and DLBCL both showed a significant reduction in FDG uptake on serial whole-body PET scans, suggesting partial regression in both cases. Although spontaneous regression of lymphoma is uncommon, this phenomenon can be successfully demonstrated by FDG-PET imaging. Therefore, serial PET imaging may play an important role in detecting this unusual event and may further enhance our understanding of the biologic behavior of this malignancy.