Which metabolic imaging, besides bone scan with 99mTc-phosphonates, for detecting and evaluating bone metastases in prostatic cancer patients? An open discussion.

Prostate cancer bone metastases occur frequently in advanced cancer and this is matter of particular attention, due to the great impact on patient's management and considering that a lot of new emerging therapeutic options have been recently introduced. Imaging bone metastases is essential to localize lesions, to establish their size and number, to study characteristics and changes during therapy. Besides radiological imaging, nuclear medicine modalities can image their features and offer additional information about their metabolic behaviour. They can be classified according to physical characteristics, type of detection, mechanism of uptake, availability for daily use. The physiopathology of metastases formation and the mechanisms of tracer uptake are essential to understand the interpretation of nuclear medicine images. Therefore, radiopharmaceuticals for bone metastases can be classified in agents targeting bone (99mTc-phosphonates, 18F-fluoride) and those targeting prostatic cancer cells (18F-fluoromethylcholine, 11C-choline, 18F-fluorodeoxyglucose). The modalities using the first group of tracers are planar bone scan, SPECT or SPECT/CT with 99mTc-diphosphonates, and 18F-fluoride PET/CT, while the modalities using the second group include 18F/11C-choline derivatives PET/CT, 18F-FDG PET/CT and PET/CT scans with several other radiopharmaceuticals described in the literature, such as 18F/11C-acetate derivatives, 18F-fluoro-5α-dihydrotestosterone (FDHT), 18F-anti-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC), 18F-2'-fluoro-5-methyl-1-ß-D-arabinofuranosyluracil (FMAU) and 68Ga-labeled-prostate specific membrane antigen (PMSA) PET/TC. However, since data on clinical validation for these last novel modalities are not conclusive and/or are not still sufficient in number, at present they can be still considered as promising tools under evaluation. The present paper considers the nuclear modalities today available for the clinical routine. This overview wants to discuss the opportunities and the drawbacks of these current diagnostic tests in a scenario where planar scintigraphy and/or SPECT with phosphonates, is the only metabolic imaging recommended by the most important Guidelines of the Scientific Societies dealing with prostate cancer. Other nuclear medicine modalities are in very few cases just cited, never recommended except in rare situations. Is there space for agents other than 99mTc-phosphonates to image bone lesions from prostate cancer?

Treatment with tandem [90Y]DOTA-TATE and [177Lu]DOTA-TATE of neuroendocrine tumours refractory to conventional therapy.

PURPOSE: Peptide receptor radionuclide therapy (PRRT) with radiolabelled somatostatin analogues has been demonstrated to be an effective therapeutic option in patients with disseminated neuroendocrine tumours (NET). Treatment with tandem [(90)Y]DOTA-TATE and [(177)Lu]DOTA-TATE may improve the efficacy of PRRT without increasing the toxicity. In a phase II study we evaluated the feasibility of combined PPRT with a high-energy beta emitter ((90)Y) and a medium-energy beta/gamma emitter ([(177)Lu) in patients with metastatic NET refractory to conventional therapy. METHODS: A group of 26 patients with metastatic NET were treated with four therapeutic cycles of alternating [[(177)Lu]DOTA-TATE (5.55 GBq) and [(90)Y]DOTA-TATE (2.6 GBq). A dosimetric evaluation was carried out after administration of [[(177)Lu]DOTA-TATE to calculate the absorbed doses in healthy organs. The acute and long-term toxicities of repeated treatment were analysed. PRRT efficacy was evaluated according to RECIST. RESULTS: Administration of tandem [(90)Y]DOTA-TATE and [[(177)Lu]DOTA-TATE induced objective responses in 42.3 % of patients with metastatic NET with a median progression-free survival longer than 24 months. Of patients with pretreatment carcinoid syndrome, 90 % showed a symptomatic response or a reduction in tumour-associated pain. The cumulative biologically effective doses (BED) were below the toxicity limit in the majority of patients, in the absence of renal function impairment. CONCLUSION: The results of our study indicates that combined [(90)Y]DOTA-TATE and [(177)Lu]DOTA-TATE therapy is a feasible and effective therapeutic option in NET refractory to conventional therapy. Furthermore, the absence of kidney damage and the evaluated cumulative BEDs suggest that increasing the number of tandem administrations is an interesting approach.

Pilot scale validation campaign of gel dosimetry for pre-treatment quality assurance in stereotactic radiotherapy.

PURPOSE: Complex stereotactic radiotherapy treatment plans require prior verification. A gel dosimetry system was developed and tested to serve as a high-resolution 3D dosimeter for Quality Assurance (QA) purposes. MATERIALS AND METHODS: A modified version of a polyacrylamide polymer gel dosimeter based on chemical response inhibition was employed. Different sample geometries (cuvettes and phantoms) were manufactured for calibration and QA acquisitions. Irradiations were performed with a Varian Trilogy linac, and analyses of irradiated gel dosimeters were performed via MRI with a 1.5 T Philips Achieva at 1 mm3 or 2 mm3 isotropic spatial resolution. To assess reliability of polymer gel data, 54 stereotactic clinical treatment plans were delivered both on dosimetric gel phantoms and on the Delta4 dosimeter. Results from the two devices were evaluated through a global gamma index over a range of acceptance criteria and compared with each other. RESULTS: A quantitative and tunable control of dosimetric gel response sensitivity was achieved through chemical inhibition. An optimized MRI analysis protocol allowed to acquire high resolution phantom dose data in timeframes of ≈ 1 h. Conversion of gel dosimeter data into absorbed dose was achieved through internal calibration. Polymer gel dosimeters (2 mm3 resolution) and Delta4 presented an agreement within 4.8 % and 2.7 % at the 3 %/1 mm and 2 %/2 mm gamma criteria, respectively. CONCLUSIONS: Gel dosimeters appear as promising tools for high resolution 3D QA. Added complexity of the gel dosimetry protocol may be justifiable in case of small target volumes and steep dose gradients.

[Radiometabolic therapy for metastatic thyroid carcinoma: overview of the literature and rational bases for the use of recombinant human TSH]. / La terapia radiometabolica del carcinoma della tiroide metastatico: overview della letteratura e basi razionali all'utilizzo del TSH umano ricombinante.

The established treatment for differentiated thyroid carcinoma (DTC) is founded on total thyroidectomy and subsequent administration of radioiodine (131I) to ablate the thyroid remnant and to treat the metastatic disease. In the case of metastatic or recurrent disease, further cycles of 131I therapy are often necessary. The condition for maximizing the effectiveness of the treatment is to have an adequate stimulation from TSH, which must be >25-30 mIU/L. This elevation is achieved either discontinuing the hormone suppression therapy for an appropriate period, or administering recombinant human TSH (rhTSH). The latter has shown good clinical efficacy in patients with residual thyroid gland and is nowadays commonly employed since it is easy to use and allows to avoid the side effects of hypothyroidism. It thus represents a good alternative to thyroid hormone withdrawal for the remnant ablation, while is still open the question if its efficacy on the management of metastatic disease is superimposable to thyroid hormone withdrawal. To this purpose, a Panel of expert reviewed the literature, assessing the advantages and disadvantages for the patient, as well as the impact in terms of cost and benefit to the National Health Service. The work of the Panel concluded with a proposal for the use of rhTSH in selected patients with metastatic DTC, in which is considered the efficacy and safety of the product and is examined its use in terms of costs; this proposal was accepted by the Italian Drug Agency resulting in an update of the indications for rhTSH.

Absorbed dose and biologically effective dose in patients with high-risk non-Hodgkin's lymphoma treated with high-activity myeloablative 90Y-ibritumomab tiuxetan (Zevalin).

PURPOSE: The aim of this study was to carry out two different dose estimation approaches in patients with non-Hodgkin's lymphoma (NHL) treated with a myeloablative amount of (90)Y-labelled ibritumomab tiuxetan (Zevalin(R)) in an open-label dose escalation study. METHODS: Twenty-seven patients with relapsed/refractory or de novo high-risk NHL receiving one myeloablative dose of (90)Y-ibritumomab tiuxetan followed by tandem stem cell reinfusion were evaluated for dose estimate. The injected activity was 30 MBq/kg in 12 patients and 45 MBq/kg in 15 patients. Dose estimation was performed 1 week prior to (90)Y-ibritumomab tiuxetan by injection of (111)In-ibritumomab tiuxetan (median activity: 200 MBq). The absorbed dose (D) and the biologically effective dose (BED) were calculated. RESULTS: The absorbed doses per unit activity (Gy/GBq) were [median (range)]: heart wall 4.6 (2.5-9.7), kidneys 5.1 (2.8-10.5), liver 6.1 (3.9-10.4), lungs 2.9 (1.5-6.8), red marrow 1.0 (0.5-1.7), spleen 7.0 (1.5-14.4) and testes 4.9 (2.9-16.7). The absorbed dose (Gy) for the 15 patients treated with 45 MBq/kg were: heart wall 17.0 (8.7-25.4), kidneys 17.1 (7.9-22.4), liver 20.8 (15.4-28.3), lungs 8.1 (5.4-11.4), red marrow 3.1 (2.0-4.0), spleen 26.2 (17.0-35.6) and testes 17.3 (9.0-28.4). At the highest activities the acute haematological toxicity was mild or moderate and of very short duration, and it was independent of the red marrow absorbed dose. No secondary malignancy or treatment-related myelodysplastic syndrome was observed. No non-haematological toxicity (liver, kidney, lung) was observed during a follow-up period of 24-48 months. CONCLUSION: The use of 45 MBq/kg of (90)Y-ibritumomab tiuxetan in association with stem cell autografting resulted in patients being free of toxicity in non-haematological organs. These clinical findings were in complete agreement with our dose estimations, considering both organ doses and BED values.

Short-term effects of pamidronate on bone turnover: can bone markers be considered predictive of the analgesic response?

Few data are available on the ability of bone markers to predict the symptomatic response to bisphosphonate therapy in patients with painful bone metastases. We evaluated the levels of bone markers in patients with bone metastases receiving pamidronate and determined the corresponding analgesic response. Forty-two patients were administered two two-week cycles of intravenous pamidronate 60 mg/week with a three-week interval in between. Serum levels of bone formation, resorption and other bone-associated markers (osteoprotegerin, osteopontin and calcium) were measured. Levels of two urinary markers were also measured and the intensity of pain and analgesic drug consumption evaluated. A mixed effects linear modelling approach was adopted to account for possible correlation among marker levels and time on study or analgesic response. We created an indicator variable that classified the patients' analgesic response as 'improved/stationary' or 'worsened' determined by patient reported intensity of pain and analgesic drug consumption. Eighteen patients 'worsened' and 24 were 'improved/stationary'. The results of the mixed effects models for testing the association between marker levels and time on study or analgesic response showed: i) the changes in marker levels over time did not significantly differ between the two groups; ii) the overall test for time on study was not statistically significant for C-terminal telopeptide of type I collagen (ICTP), osteoprotegerin and osteopontin; iii) in contrast, ICTP and osteoprotegerin were significantly associated with analgesic response. Biochemical markers of bone turnover, in particular ICTP and osteoprotegerin seem promising for predicting and objectively assessing the analgesic response to pamidronate treatment.

Role of surgery in treatment of advanced differentiated thyroid carcinomas.

Well-differentiated thyroid carcinomas are characterized by a long natural history. The evolution of the reconstructive techniques and the improvement of the peri-operative anaestesiologist management of the patient have contributed, over the last few years, to a progressive widening of demolitive surgery. The aims of enlarged surgical treatment in differentiated advanced thyroid carcinomas are to guarantee respiratory and alimentary functions as well as symptomatic benefits, to obtain local control of the disease and the recovery of adjuvant therapeutic options, such as metabolic and conventional radiation. In the present study, 27 patients who underwent enlarged surgery for differentiated thyroid carcinoma involving the superior digestive-aerial ways (SDAW) were treated between January 1992 and December 2002. The following results were achieved: Group 1 (7 patients): partial resection of the trachea and larynx: 57% of patients are Not Evidence Disease (NED) at a mean follow-up of 7 years; the other 43% are Alive With Disease (AWD). Group 2 (4 patients): total laryngectomy associated with emi-pharyngectomy or oesophagectomy of whom 50% are NED at a mean follow-up of 6 years. Group 3 (4 patients): mediastinum dissection in sternotomy of whom 3 patients NED at 7, 8 and 12 years of follow-up, respectively (75%). Group 4 (12 patients): latero-cervical, retro-clavear and subclavear dissection, of whom 75% of cases are NED at a mean follow-up of 5.1 years. Enlarged surgery is justified by the long natural history of the differentiated histotypes and the advantages it offers to adjuvant therapies. An essential principle, in the case of enlarged thyroid resections, is the modularity. With respect to the loco-regional spread of the disease, the surgeon has to study a treatment plan with a surgical procedure that involves the various elective districts of spreading, planning each surgical step with the entity of demolition and reconstruction being modulated according to the demand.

Axillary lymph node staging in breast cancer by 2-fluoro-2-deoxy-D-glucose-positron emission tomography: clinical evaluation and alternative management.

BACKGROUND: Surgical removal of axillary lymph node and histologic examination for metastases are used to determine whether adjuvant treatment is necessary for patients with breast cancer. Axillary lymph node dissection (ALND) is a costly procedure associated with various side effects, and 80% or more of patients with tumors of 20 mm or less are lymph node negative and might avoid ALND. In this study, we evaluated whether an alternative, noninvasive method--i.e., positron emission tomography (PET) with 2-[(18)F]fluoro-2-deoxy-D-glucose (FDG)-- could be used to determine axillary lymph node status in patients with breast cancer. METHODS: One hundred sixty-seven consecutive patients with breast cancers of 50 mm or less (range = 5-50 mm; mean = 21 mm) scheduled for complete ALND were studied preoperatively with FDG-PET, and then PET and pathology results from ALND were compared. All statistical tests were two-sided. RESULTS: The overall sensitivity, specificity, and accuracy of lymph node staging with PET were 94.4% (PET detected 68 of 72 patients with axillary involvement; 95% confidence interval [CI] = 86.0% to 98.2%), 86.3% (82 of 95 patients without axillary involvement; 95% CI = 77.8% to 91.9%), and 89.8% (150 of 167 patients with breast cancer; 95% CI = 84.2% to 93.6%), respectively. Positive- and negative-predictive values were 84.0% (68 patients with histologically positive lymph nodes of 81 patients with positive FDG-PET scan; 95% CI = 74.2% to 90.5%) and 95.3% (82 patients with histologically negative lymph nodes of 86 patients with negative FDG-PET scan; 95% CI = 88.2% to 98.5%), respectively. When PET results for axillary metastasis were analyzed by tumor size, the diagnostic accuracy was similar for all groups (86.0%-94.2%), with higher sensitivity for tumors of 21-50 mm (98.0%) and higher specificity for tumors of 10 mm or less (87.8%), and the range was 93.5%-97.3% for negative-predictive values and 54.5%-94.1% for positive-predictive values. Among the 72 patients with axillary involvement, PET detected three or fewer metastatic lymph nodes in 27 (37.5%) patients, about 80% of whom had no clinically palpable axillary lymph nodes. CONCLUSIONS: Noninvasive FDG-PET appears to be an accurate technique to predict axillary status in patients with breast cancer and thus to identify patients who might avoid ALND. These results should be confirmed in large multicenter studies.

Imaging with 131I-labeled monoclonal antibodies to a high-molecular-weight melanoma-associated antigen in patients with melanoma: efficacy of whole immunoglobulin and its F(ab')2 fragments.

In vitro experiments selected optimal conditions to radiolabel with 131I the whole immunoglobulin and F(ab')2 fragments of the monoclonal antibody (MoAb) 225.28S to a high-molecular-weight melanoma-associated antigen (HMW-MAA). Injection of the radiolabeled whole immunoglobulin and F(ab')2 fragments of the MoAb 225.28S into eight patients with melanoma resulted in the accumulation of radioactivity in 10 of 18 metastases. This localization is specific because of the close relationship between detection of HMW-MAA in lesions by immunohistochemical techniques and outcome of immunoscintigraphy and because of the different distribution in tumors and adjacent tissues of radiolabeled F(ab')2 fragments of MoAb 225.28S compared with 99mTc-pertechnetate and with radiolabeled F(ab')2 fragments of MoAb 4C4 to hepatitis B surface antigen. F(ab')2 fragments are superior to whole immunoglobulins to perform immunoscintigraphy, since they markedly reduce the background in bone marrow, liver, and spleen. The sensitivity of the procedure allows the detection of lesions with a diameter of at least 1.5 cm and is influenced by the level of the HMW-MAA in lesions and by their anatomical site.

Orchiectomy alone in clinical stage I nonseminomatous testis cancer: a critical appraisal.

Sixty-two consecutive patients with clinical stage I nonseminomatous testicular cancer were entered into a prospective study to receive no treatment after orchiectomy until clinical evidence of recurrent disease. Of 59 evaluable cases, 41 (69.5%) remained continuously disease free for a median duration of 30 months (range, 18 to 46 months), and evidence of metastatic disease developed in 18 patients (30.5%) from 2 to 36 months after orchiectomy. The median disease-free interval for relapsing patients was 6 months. Retroperitoneal metastases developed in ten patients; seven patients had pulmonary metastases, and one patient had progressive elevation of the serum alpha-fetoprotein level. Relapses were significantly more frequent in patients with either embryonal carcinoma, infiltrating testicular cancer (pT greater than 1), peritumoral vascular invasion, or in those who underwent transscrotal biopsy. One patient with relapse refused salvage therapy and died. The remaining 17 patients have been rendered disease free with cisplatin combination chemotherapy and/or surgery. However, two patients showed further recurrence, with one in the lung and the other one also in the retroperitoneal nodes. In our opinion, surveillance following orchiectomy will provide useful information in clinical stage I nonseminomatous testicular cancer, but it is a difficult study. For the time being, it should be restricted to specialized centers only. In the meanwhile, retroperitoneal lymphadenectomy remains the standard treatment.

Osteoprotegerin and osteopontin serum values in postmenopausal advanced breast cancer patients treated with anastrozole.

Osteoprotegerin (OPG) is a potent antiresorptive molecule that binds NF-kappaB ligand, the final effector for osteoclastogenesis. OPG production is regulated by a number of cytokines and hormones. Osteopontin (OPN) is a secreted adhesive glycoprotein involved in tumour angiogenesis, and also a non-collagenous protein involved in bone turnover. OPN serum value is associated with tumour burden and survival in advanced breast cancer patients. The short-term effects of anastrozole on OPG and OPN serum values, and the usefulness of these analytes during follow-up were studied in 34 consecutive advanced breast cancer patients receiving anastrozole 1 mg/day. Blood samples were taken before treatment and at 2, 4, 8 and 12 weeks. OPG and OPN values were measured by ELISA. The results were analysed for all patients, and also separately for patients with (group A, 22 patients) and without (group B, 12 patients) bone metastasis. Whether the survival of all patients was related to their OPN serum values was also tested by placing patients into three groups (terciles) according to their baseline OPN values. No significant changes in OPG and OPN values were observed in the complete patient group. There was no difference in baseline OPG and OPN serum values between patients in groups A and B. In group A, a significant percentage increase in both OPG and OPN values from baseline was detected during treatment. No significant changes were reported for group B patients. Furthermore, in group A, a significant increase in both analytes was evident only for patients with progressive disease (PD). The Kaplan-Meier adjusted survival estimates for patients grouped according to tercile OPN values differed significantly (P = 0.001, log rank test). In conclusion, in the short term, anastrozole does not seem to affect OPG and OPN serum values in patients without bone disease. OPG and OPN appear to be useful predictors of the outcome of skeletal disease and elevated OPN values may be associated with short survival in advanced breast cancer patients.

CA 15.3 determination in patients with breast cancer: clinical utility for the detection of distant metastases.

In 81 healthy women, 26 pregnant women, 25 patients with fibrocystic disease and 144 breast cancer patients, the overall diagnostic sensitivity and specificity of the CA 15.3 test was 27 and 97%, respectively. The positive and negative predictive values were 93 and 43%. In 150 node-negative patients taking part in a chemoprevention trial CA 15.3 was assayed at baseline and every 4 months for a median follow-up of 24 months (range 4-48). In these patients, 5 had local recurrences, 1 had a regional recurrence, 9 had distant metastases and 3 developed cancer in the contralateral breast. Among the patients with recurrences, those with distant metastases showed the highest ratio of CA 15.3 increase (8/9); in local and regional recurrences, this ratio was lower (2/6). The patients with contralateral breast cancer had no significant increase in CA 15.3. Patients in whom metastases were detected showed an increase in CA 15.3 4-48 months before clinical or instrumental detection of the metastases.

Single-dose intraperitoneal radioimmunotherapy with the murine monoclonal antibody I-131 MOv18: clinical results in patients with minimal residual disease of ovarian cancer.

Sixteen of 19 enrolled patients with minimal residual disease of ovarian cancer (macroscopic disease < 5 mm or positive blind biopsies and/or positive peritoneal washing), demonstrated by surgical second-look, underwent intraperitoneal radioimmunotherapy (RIT) with the radiolabelled monoclonal antibody I-131 MOv18 (mean dose 14 mg of MOv18 with 3700 GBq of I-131) 30-40 days after the second-look procedure. Clinical follow-up and/or third-look evaluation performed 90 days after RIT showed complete response (CR) in 5 patients, no change (NC) in 6 patients and progressive disease (PD) in 5 patients. Follow-up study showed long-term maintained CR in 1 patient (34 months) and relapses in the other 4 patients after a mean disease-free period of 10.5 months. 5 NC patients showed clinical or instrumental progression after a mean disease-free period of 13 months. The toxicity of RIT was negligible. Only 1 patient showed mild and transient bone marrow suppression (platelet count nadir 52,000 mm3 after 30 days). HAMA production was demonstrated in 94% (15/16) of patients. In conclusion, RIT appears to be a very promising therapeutic approach to treat minimal residual disease of ovarian cancer.

Somatostatin receptor imaging of small cell lung cancer (SCLC) by means of 111In-DTPA octreotide scintigraphy.

Somatostatin receptors have been described on the membrane of neoplastic cells derived from the APUD system and their expression has also been demonstrated on small cell lung cancer (SCLC) in vitro and in vivo. 21 patients with SCLC were studied using 111In-octreotide (111In-OCT) scintigraphy. Scintigraphic examinations were performed following intravenous (i.v.) injection of 111 MBq 111In-OCT with whole-body scintigraphy and planar scintigraphy of the thorax as well as the SPET technique. No short-term side effects were described following 111In-OCT administration. We studied the 111In-OCT biodistribution in 3 patients with serial scintigraphies at 1, 5 and 24 h. We used the 5 h as standard scanning time for the following 18 patients. The scintigraphic results were compared with those of other conventional diagnostic procedures. 111In-OCT detected 86% (48/56) of the lesions already known at the time of scintigraphy. It was positive in all 20 SCLC patients and negative in one lung adenocarcinoma. 111In-OCT showed high sensitivity for mediastinal metastases (94%) and good sensitivity for bone metastases (75%) and abdominal lymph node metastases (71%). 111In-OCT did not detect two liver metastases. 111In-OCT detected five unknown lesions which were confirmed by other diagnostic examinations. 111In-OCT was also effective in cancer patients with low levels of NSE. Our study shows that 111In-OCT scintigraphy is a reliable, non-invasive technique to detect primary SLCL and its locoregional or distant metastases. The clinical utility of receptor status characterisation obtained with 111In-OCT scintigraphy should be evaluated by means of an appropriate prospective study.

The objective measurement of remission and progression in metastatic breast cancer by use of serum tumour markers. European Group for Serum Tumour Markers in Breast Cancer.

An established biochemical index for monitoring therapy in patients with metastatic breast cancer was tested prospectively in a multicentre study. The index uses two serum tumour markers--carcinoembryonic antigen (CEA) and carbohydrate antigen 15-3 (CA15-3) along with erythrocyte sedimentation rate (ESR). 67 patients treated by either endocrine or chemotherapy had CA15-3, CEA and ESR measured at diagnosis of metastases and sequentially during therapy. Two markers, CA15-3 and CEA, were measured on a further 16 patients giving a total of 83 patients who were assessable for CA15-3 and CEA. Of the patients with CA15-3, CEA and ESR measured at diagnosis of metastases 84% (56/67) had elevation of 1 or more markers. During therapy the number with elevated marker(s) rose to 96% (64/67). Changes in the markers were in line with and often pre-dated therapeutic outcome as assessed by the International Union Against Cancer (UICC) criteria both for remission and progression. Patients without elevation of markers on diagnosis subsequently showed a rise in the marker(s) at or before documented disease progression by UICC. The 3 women in whom markers were at no time significantly elevated remain in remission. The results using CA15-3 and CEA were similar but 12% less patients were assessable. CA15-3 and CEA (with and without ESR) provide an objective method to guide therapy in patients with metastatic breast cancer.

Accuracy evaluation of fusion of CT, MR, and spect images using commercially available software packages (SRS PLATO and IFS).

PURPOSE: A problem for clinicians is to mentally integrate information from multiple diagnostic sources, such as computed tomography (CT), magnetic resonance (MR), and single photon emission computed tomography (SPECT), whose images give anatomic and metabolic information. METHODS AND MATERIALS: To combine this different imaging procedure information, and to overlay correspondent slices, we used commercially available software packages (SRS PLATO and IFS). The algorithms utilize a fiducial-based coordinate system (or frame) with 3 N-shaped markers, which allows coordinate transformation of a clinical examination data set (9 spots for each transaxial section) to a stereotactic coordinate system. The N-shaped markers were filled with fluids visible in each modality (gadolinium for MR, calcium chloride for CT, and 99mTc for SPECT). The frame is relocatable, in the different acquisition modalities, by means of a head holder to which a face mask is fixed so as to immobilize the patient. Position errors due to the algorithms were obtained by evaluating the stereotactic coordinates of five sources detectable in each modality. RESULTS: SPECT and MR position errors due to the algorithms were evaluated with respect to CT: deltax was < or = 0.9 mm for MR and < or = 1.4 mm for SPECT, deltay was < or = 1 mm and < or = 3 mm for MR and SPECT, respectively. Maximal differences in distance between estimated and actual fiducial centers (geometric mismatch) were in the order of the pixel size (0.8 mm for CT, 1.4 mm for MR, and 1.8 mm for SPECT). In an attempt to distinguish necrosis from residual disease, the image fusion protocol was studied in 35 primary or metastatic brain tumor patients. CONCLUSIONS: The image fusion technique has a good degree of accuracy as well as the potential to improve the specificity of tissue identification and the precision of the subsequent treatment planning.

Double-tracer scintigraphy with 67Ga-citrate and 99mTc-sulfur colloid in the diagnosis of hepatic tumors.

A method of liver scanning based on a subtraction technique with simultaneous use of two tracers, 67Ga-citrate and 99mTc-sulfur colloid, is described. The subtraction technique isolates radiogallium uptake by the space-occupying hepatic lesions by subtracting interference due to tracer uptake by healthy hepatic tissue. In 82 patients, the method yielded a correct result in 94.7% of the positive scans and in 97.7% of the negatives. Two false positives and one false negative occurred. Very poor results were obtained in the same patients using conventional technetium and gallium scans: only 20.7% of these interpretations were correct. The method proved very helpful in differentiating malignant from benign lesions.

Which kinds of lymph node metastases can FDG PET detect? A clinical study in melanoma.

UNLABELLED: The purposes of this study were to establish the diagnostic accuracy of FDG PET for lymph node metastases and to determine the smallest detectable volume of disease. METHODS: Using FDG PET, we preoperatively studied 56 lymph node basins in 38 patients with a clinical or instrumental diagnosis of lymph node metastases from melanoma. All lymph node basins underwent node dissection. The FDG PET results were compared with the postoperative histopathology results. PET images were obtained using a GE 4096 WB scanner, after injection of a mean activity of 496 MBq (range, 366-699 MBq) of FDG. RESULTS: The efficacy of FDG PET in the diagnosis of involved lymph node basins was good. Sensitivity was 95% (35/37); specificity, 84% (16/19); accuracy, 91% (51/56); positive predictive value, 92% (35/38); and negative predicative value, 89% (16/18). Metastases were shown histologically in 114 of 647 surgically removed lymph nodes. FDG PET detected 100% of metastases > or = 10 mm, 83% of metastases 6-10 mm, and 23% of metastases < or = 5 mm. Moreover, FDG PET had high sensitivity (> or = 93%) only for metastases with more than 50% lymph node involvement or with capsular infiltration. CONCLUSION: Our study shows that FDG PET has a reasonable sensitivity and specificity for detecting the presence or absence of lymph node metastases in patients with melanoma. However, even if able to detect small volumes of subclinical macroscopic disease, FDG PET cannot detect subclinical microscopic disease with acceptable sensitivity. The specificity of FDG PET is good, but some false-positive results may occur.

Gallium-67 scintigraphy evaluation of therapy in non-Hodgkin's lymphoma.

UNLABELLED: Patients with diffuse large cell lymphoma may achieve complete remission (CR) after chemotherapy, and the time to reach CR may be predictive of treatment outcome. Partial remission, or recurrence from CR, is associated with poor survival. Gallium-67 imaging has proven to be useful in evaluating lymphoma patients. In tumor models, this radiotracer is an indicator of tumor viability. Gallium-67 uptake is seen only in avid and viable lymphoma tissue, not in fibrotic or necrotic tissue. In this study, we prospectively assessed the ability of this radiotracer to define residual disease. In addition, we evaluated the possibility of predicting the clinical outcome in patients with diffuse cell lymphoma on the basis of scan positivity during chemotherapy. METHODS: Thirty-three consecutive patients with histologically proven diffuse large cell lymphoma were investigated with 67Ga scintigraphy 48-72 hr after injection of 185-259 MBq 67Ga-citrate for staging and during follow-up after four to six cycles of intensive chemotherapy. Patients were monitored for a mean of 56.0 mo (range 7-90 mo), and they were restaged using physical examination, CT and all necessary imaging modalities. RESULTS: Patients were divided into two groups according to the positivity or negativity of 67Ga scan after four to six cycles of chemotherapy. Of the 33 patients studied, 14 (42.4%) showed persistent abnormal uptake of 67Ga-citrate after four to six cycles of chemotherapy. In this group, 9 patients (64.2%) died of lymphoma at a mean of 24.3 mo from presentation with the diagnosis (range 7-71 mo). Four patients had no evidence of disease at an average of 71.7 mo after diagnosis, and 1 patient was considered to be in partial remission. In the second group of 19 67Ga-negative patients, after four to six cycles of chemotherapy, 4 died and 15 are alive and considered to be in CR. A statistical analysis of the association between 67Ga scan results after four to six cycles of chemotherapy and survival was performed using the log-rank test; there was a statistically significant association between scan results and survival (p=0.00125). CONCLUSION: We conclude that 67Ga scintigraphy is an excellent predictor of residual tumor viability in lymphoma patients and that persistent positivity of the scan predicts poor outcome and may justify a change in treatment.