Primary skeletal muscle marginal zone lymphoma with persistent tissue tropism and PET-avidity

This study describes a case of extra-nodal marginal zone lymphoma presenting in skeletal muscle and recurring on multiple occasions in the same tissue at other sites. In this case, 18F-fluoro-deoxy-glucose positron emission tomography scanning was the most useful surveillance modality.

The impact of PET-CT in suspected recurrent ovarian cancer: A prospective multi-centre study as part of the Australian PET Data Collection Project

OBJECTIVE

To assess the impact of FDG PET-CT on the management of patients with suspected recurrent ovarian cancer and to determine the incremental information provided by PET-CT.

METHODS

This was a prospective, multi-centre, cohort study. Ninety women (mean age 59.9 years; age range 35-85 years) with a previous history of treated epithelial ovarian carcinoma and suspected recurrence based on elevated CA-125, anatomical imaging or clinical symptoms were studied with FDG PET-CT across two States. Referring doctors were asked to specify a management plan pre-PET, if management was altered after PET-CT and, the impact (rated - none, low, medium, high) of PET-CT on patient management. The pre-PET management plan could include radiotherapy, chemotherapy, surgery, and 'other' including observation. Patients were followed at 6 and 12 months and clinical status, evidence of recurrence and progression were recorded.

RESULTS

Patients were referred by 34 individual specialists. At least 168 additional sites of disease in 61 patients (68%), not identified by conventional imaging were identified by PET-CT. In 77% the additional lesions were located below the diaphragm and most were nodal or peritoneal. PET-CT affected management in 60% (49% high, 11% medium impact). Patients where more disease was detected with PET-CT were more likely to progress in the following 12 months.

CONCLUSIONS

For women with previously treated ovarian carcinoma with recurrent disease, PET-CT can: a) alter management in close to 60% of patients, b) detect more sites of disease than abdominal and pelvic CT, c) is superior in the detection of nodal, peritoneal and subcapsular liver disease and d) offers the opportunity for technology replacement in this setting.

Comparison of CT and positron emission tomography/CT coregistered images in planning radical radiotherapy in patients with non-small-cell lung cancer

Imaging with F-18 fluorodeoxyglucose positron emission tomography (PET) significantly improves lung cancer staging, especially when PET and CT information are combined. We describe a method for obtaining CT and PET images at separate acquisitions, which allows coregistration and incorporation of PET information into the radiotherapy (RT) planning process for non-small-cell lung cancer. The influence of PET information on RT planning was analysed for 10 consecutive patients. Computed tomography and PET images were acquired with the patient in an immobilization device, in the treatment position. Using specially written software, PET and CT data were coregistered using fiducial markers and imported into our RT planning system (Cadplan version 6). Treatment plans were prepared with and without access to PET/CT coregistered images and then compared. PET influenced the treatment plan in all cases. In three cases, geographic misses (gross tumour outside planning target volume) would have occurred had PET not been used. In a further three cases, better planning target volume marginal coverage was achieved with PET. In four patients, three with atelectasis, there were significant reductions in V20 (percentage of the total lung volume receiving 20 Gy or more). Use of coregistered PET/CT images significantly altered treatment plans in a majority of cases. This method could be used in routine practice at centres without access to a combined PET/CT scanner .

Phenolic Michael Reaction Acceptors: Combined Direct and Indirect Antioxidant Defenses Against Electrophiles and Oxidants

The implications of oxidative stress in the pathogenesis of many chronic human diseases has led to the widely accepted view that low molecular weight antioxidants could be beneficial and postpone or even prevent these diseases. Small molecules of either plant or synthetic origins, which contain Michael acceptor functionalities (olefins or acetylenes conjugated to electron-withdrawing groups) protect against the toxicity of oxidants and electrophiles indirectly, i.e., by inducing phase 2 cytoprotective enzymes. Some of these molecules, e.g., flavonoid and curcuminoid analogues that have phenolic hydroxyl groups in addition to Michael acceptor centers, are also potent direct antioxidants, and may therefore be appropriately designated: bifunctional antioxidants. By use of spectroscopic methods we identified phenolic chalcone and bis(benzylidene)acetone analogues containing one or two Michael acceptor groups, respectively, as very efficient scavengers of two different types of radicals: (a) the nitrogen-centered 2,2'-azinobis-(3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS.+) radical cation, and (b) the oxygen-centered galvinoxyl (phenoxyl) radical. The most potent scavengers are those also bearing hydroxyl substituents on the aromatic ring(s) at the ortho-position(s). The initial reaction velocities are very rapid and concentration-dependent. In the human keratinocyte cell line HaCaT, the same compounds coordinately increase the intracellular levels of glutathione, glutathione reductase, and thioredoxin reductase. Thus, such bifunctional antioxidants could exert synergistic protective effects against oxidants and electrophiles which represent the principal biological hazards by: (i) scavenging hazardous oxidants directly and immediately; and (ii) inducing the phase 2 response to prevent and resolve the consequences of hazardous processes that are already in progress, i.e., acting indirectly, but with much more diverse and long-lasting effects.

"Magnetic resonance imaging negative positron emission tomography positive" temporal lobe epilepsy: FDG-PET pattern differs from mesial temporal lobe epilepsy

PURPOSE

Some patients with temporal lobe epilepsy (TLE) lack evidence of hippocampal sclerosis (HS) on MRI (HS-ve). We hypothesized that this group would have a different pattern of 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET) hypometabolism than typical mesial TLE/HS patients with evidence of hippocampal atrophy on magnetic resonance imaging (MRI) (HS+ve), with a lateral temporal neocortical rather than mesial focus.

PROCEDURES

Thirty consecutive HS-ve patients and 30 age- and sex-matched HS+ve patients with well-lateralized EEG were identified. FDG-PET was performed on 28 HS-ve patients and 24 HS+ve patients. Both groups were compared using statistical parametric mapping (SPM), directly and with FDG-PET from 20 healthy controls.

RESULTS

Both groups showed lateralized temporal hypometabolism compared to controls. In HS+ve, this was antero-infero-mesial (T = 17.13); in HS-ve the main clustering was inferolateral (T = 17.63). When directly compared, HS+ve had greater hypometabolism inmesial temporal/hippocampal regions (T = 4.86); HS-ve had greater inferolateral temporal hypometabolism (T = 4.18).

CONCLUSIONS

These data support the hypothesis that focal hypometabolism involves primarily lateal neocortical rather than mesial temporal structures in 'MRI-negative PET-positive TLE.'

In vivo tracking of macrophage activated killer cells to sites of metastatic ovarian carcinoma

Radio-labelling of blood cells is an established technique for evaluating in vivo migration of normal cells to sites of pathology such as infection and haemorrhage. A limitation of cellular immunotherapies to induce anti-tumour responses is in part due to the uncertain ability of cellular effectors to reach their intended target. We extended the approach of cell radiolabelling to accurately examine the in vivo distribution of cellular immunotherapy with ex-vivo macrophage activated killer (MAK) cells. We describe the use of two methods of cell labelling for tracking the destination of autologous-derived macrophage activated killer (MAK) cells linked to the bi-specific antibody MDX-H210 delivered either by intravenous (i.v.) or intraperitoneal (i.p.) injection in ten patients with peritoneal relapse of epithelial ovarian carcinoma. Our results demonstrate the feasibility of generating high numbers and purity of GMP quality MAK cells, which can be radiolabelled with (18)F-FDG or (111)In-oxime. MAK cell administration produced minimal infusional toxicity and demonstrated a reproducible pattern of in vivo distribution and active in vivo tracking to sites of known tumour following 8 of 16 i.v. infusions or 4 of 6 i.p. infusions. However, the leakage of (18)F-FDG limited the ability to confidently confirm the tracking of MAK cells to tumour in all cases and improved PET labels are required. The addition of MDX-H210 bispecific antibody did not alter the distribution of cells to tumour sites, but did accelerate the clearance of i.v. administered MAK cells from the pulmonary circulation. This data demonstrates that cellular cancer immunotherapies may be successfully delivered to the sites of active tumour following either i.v. or i.p. injection in a proportion of patients with metastatic cancer. Incorporation of tracking studies in early cycles of cellular immunotherapy may allow selection of patients who demonstrate successful targeting of the immunotherapy for ongoing treatment.

Positron emission tomography of stage IV mucosa-associated lymphoid tissue lymphoma confined to the four major salivary glands

In a patient with stage IVA marginal zone lymphoma, (18)F-fluorodeoxyglucose-positron emission tomography indicated that the disease was confined to the four major salivary glands. The positron emission tomography findings encouraged the use of radiotherapy with curative intent in this case. After 30 Gy of external beam radiotherapy to the parotid and submandibular glands, the patient entered a complete remission and remains free from progression more than 4 years later.

Management of paediatric thyroid carcinoma: recent experience with recombinant human thyroid stimulating hormone in preparation for radioiodine therapy

BACKGROUND

Thyroid carcinoma in children is rare and raises unique management issues. Although metastatic disease is more common in this age group, prognosis remains good with appropriate treatment. The aim of the study was to report recent experience in the management of differentiated thyroid carcinoma in children, especially in the use of radioiodine after recombinant human thyroid stimulating hormone (rhTSH) stimulation.

METHODS

Eight patients, aged 5-17 years (five were boys) presented following total thyroidectomy for thyroid carcinoma between May 2003 and June 2005. Seven had papillary carcinoma and one had follicular carcinoma. Five had known lymph node metastases and one had pulmonary metastases at presentation. Four patients had previously received therapeutic irradiation for malignancy. All eight underwent diagnostic iodine scans, seven with rhTSH stimulation. Seven went on to receive radioiodine treatment as hospital inpatients, comanaged by the paediatric and nuclear medicine units. The dosage of 131I ranged from 1.5 to 3.7 x 10(9) Bq. All except one were prepared by rhTSH stimulation.

RESULTS

Seven of eight patients had significant uptake in the neck on diagnostic scan and two had pulmonary abnormalities. Six of seven evaluable patients achieved complete thyroid ablation. Both patients with pulmonary abnormalities had scan resolution, although one of them only after a second radioiodine treatment. All patients had thyroxine replacement in doses to suppress TSH and all remain alive and well at time of carrying out this study.

CONCLUSION

Optimal management of paediatric thyroid carcinoma necessitates a multidisciplinary approach. Radioiodine therapy under rhTSH is an effective and safe adjuvant treatment in this special subgroup.

Imaging with FLT-PET demonstrates that PF-477736, an inhibitor of CHK1 kinase, overcomes a cell cycle checkpoint induced by gemcitabine in PC-3 xenografts

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Background: The development of strategies to monitor the molecular and cellular response to novel agents that target the cell cycle is vital to provide proof of mechanism and biological activity of these compounds. The protein kinase CHK1 is activated following DNA damage in the S and G2-phases of the cell cycle and mediates cell cycle arrest. In vitro studies demonstrate that inhibition of CHK1 can overcome cell cycle arrest induced by DNA damage and enhance cytotoxic activity of DNA damaging agents. In vivo studies show that combining DNA damaging agents with a CHK1 inhibitor potentiates antitumor activity. We hypothesize that functional imaging with 18F-fluorine-L-thymidine (FLT), a PET-tracer where tumor uptake is maximal in the S and G2 phases of the cell cycle can be used to non-invasively monitor the induction and therapeutic inhibition of a cell cycle checkpoint in vivo. Methods: Nude mice harbouring PC-3 xenografts were treated with vehicle controls, gemcitabine, the CHK1-inhibitor PF-477736 or gemcitabine + PF-477736. FLT-PET scans were performed and tumors harvested for ex-vivo biomarkers to assess S-phase, M-phase and DNA-repair. Results: Gemcitabine induced a 8.3 ±0.8 fold increase in tumoral uptake of FLT at 21 hours that correlated with a 3.3 ±0.2-fold increase in thymidine kinase activity and S-phase arrest as demonstrated by BrdU incorporation and elevated expression of cyclin-A. Treatment with PF-477736 at 17 hours after gemcitabine abrogated the early FLT-flare at 21 hours by 82% (p<0.001). This was associated with both an increased fraction of cells in mitosis and G1-phase of the cell cycle as determined by phos-histone H3 and flow cytometry. Furthermore, the combination of gemcitabine and PF-477736 enhanced DNA damage as measured by phos-gamma-H2AX and significantly delayed tumor growth when compared to tumors treated with gemcitabine alone. Conclusion: These data clearly indicate that the CHK1-inhibitor PF-477736 can overcome the cell cycle checkpoint induced by gemcitabine and increase associated DNA damage in tumors in-vivo. The PET studies indicate that functional imaging with FLT-PET is a promising strategy to monitor responses to therapeutic agents that target cell cycle checkpoints.

[Table: see text]

In vivo tracking for cell therapies

The success of a particular cellular therapy regime requires the therapeutic agent to migrate expeditiously to the intended target in sufficient numbers and to provoke a desirable response. There are many variables associated with the production, administration and host that need to be investigated to maximize the resulting therapeutic benefit. The large number of factors which may contribute to, or detract from, treatment efficacy can make therapy optimization an arduous procedure. Direct visualization of in vivo migration patterns using nuclear medicine techniques greatly assists the appraisal of the multitude of variables. Conventional radionuclide cell labeling is a proven, simple and sensitive technique which can provide whole body biodistribution information. Labeling with a PET isotope offers greater sensitivity, much improved 3-dimensional resolution and quantification. In general, current efforts are increasingly concentrating on this technology. Imaging studies can supply definitive evidence of successful targeting and allow quantification of the degree of migration to a particular site. Incorporating tracking studies into clinical trials of cell-based therapy at the earliest stage can provide proof of mechanism of the therapy and permit evaluation of the many contributory variables, even on a patient-by-patient basis.

Oxaliplatin combined with infusional 5-fluorouracil and concomitant radiotherapy in inoperable and metastatic rectal cancer: a phase I trial

The aim of this study was to define the recommended dose of oxaliplatin when combined with infusional 5-fluorouracil (5-FU) and concurrent pelvic radiotherapy. Eligible patients had inoperable rectal cancer, or symptomatic primary rectal cancer with metastasis. Oxaliplatin was given on day 1 of weeks 1, 3 and 5 of radiotherapy. Dose level 1 was oxaliplatin 70 mg m(-2) with 5-FU 200 mg m(-2) day(-1) continuous infusion 96 h week(-1). On dose level 2, the oxaliplatin dose was increased to 85 mg m(-2). On dose level 3, the duration of the 5-FU was increased to 168 h per week. Pelvic radiotherapy was 45 Gray (Gy) in 25 fractions over 5 weeks with a boost of 5.4 Gy. Fluorine-18 fluoro deoxyglucose and Fluorine-18 fluoro misonidazole positron emission tomography (FDG-PET and FMISO-PET) were used to assess metabolic tumour response and hypoxia. In all, 16 patients were accrued. Dose-limiting toxicities occurred in one patient at level 2 (grade 3 chest infection), and two patients at level 3 (grade 3 diarrhoea). Dose level 2 was declared the recommended dose level. FDG-PET imaging showed metabolic responses in 11 of the 12 primary tumours assessed. Four of six tumours had detectable hypoxia on FMISO-PET scans. The addition of oxaliplatin to infusional 5-FU chemoradiotherapy was feasible and generally well tolerated. For future trials, oxaliplatin 85 mg m(-2) and 5-FU 200 mg m(-2) day(-1) continuous infusion 96 h week(-1) is the recommended dose when combined with 50.4 Gy of pelvic radiotherapy.

18F-fluorodeoxyglucose positron emission tomography in evaluation of germ cell tumor after chemotherapy

OBJECTIVES

To evaluate the role of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) in the assessment of germ cell tumors after chemotherapy.

METHODS

We reviewed patients' records for the histologic findings and clinical outcome. 18F-FDG PET results were correlated with tissue histologic features where available; and if not available, the correlation was with the clinical outcome.

RESULTS

A total of 45 PET studies were performed on 38 patients (age range 19 to 64 years, median 31). All patients had received chemotherapy. In the nonseminomatous germ cell tumor (NSGCT) group, of the 31 patients with one scan, 18 PET scans were reported as positive, with only 2 not having active disease. Of the 12 negative scans, 6 showed teratoma, 1 tumor, and 5 did not show active disease. The equivocal scan revealed thyroid adenoma. In the seminoma group, the PET scans correlated well with the clinical and histologic outcomes. Four patients underwent salvage chemotherapy, and in this subgroup, the PET findings also correlated with the outcome.

CONCLUSIONS

(18)F-FDG PET is a promising tool as an adjunct to current imaging techniques in detecting residual viable germ cell tumor after chemotherapy. In NSGCT, a positive PET scan was accurate in 16 of 18 patients, although negative PET studies did not exclude the presence of disease, mainly because of the presence of teratoma. In seminoma, a negative 18F-FDG PET study correlated with a favorable clinical outcome. PET was also predictive of the response to salvage chemotherapy and was highly specific for active tumor in both NSGCT and seminoma.

MRI-negative PET-positive temporal lobe epilepsy: a distinct surgically remediable syndrome

Most patients with non-lesional temporal lobe epilepsy (NLTLE) will have the findings of hippocampal sclerosis (HS) on a high resolution MRI. However, a significant minority of patients with NLTLE and electroclinically well-lateralized temporal lobe seizures have no evidence of HS on MRI. Many of these patients have concordant hypometabolism on fluorodeoxyglucose-PET ([18F]FDG-PET). The pathophysiological basis of this latter group remains uncertain. We aimed to determine whether NLTLE without HS on MRI represents a variant of or a different clinicopathological syndrome from that of NLTLE with HS on MRI. The clinical, EEG, [18F]FDG-PET, histopathological and surgical outcomes of 30 consecutive NLTLE patients with well-lateralized EEG but without HS on MRI (HS-ve TLE) were compared with 30 consecutive age- and sex-matched NLTLE patients with well-lateralized EEG with HS on MRI (HS+ve TLE). Both the HS+ve TLE group and the HS-ve TLE patients had a high degree of [18F]FDG-PET concordant lateralization (26 out of 30 HS-ve TLE versus 27 out of 27 HS+ve TLE). HS-ve TLE patients had more widespread hypometabolism on [18F]FDG-PET by blinded visual analysis [odds ratio (OR = + infinity (2.51, -), P = 0.001]. The HS-ve TLE group less frequently had a history of febrile convulsions [OR = 0.077 (0.002-0.512), P = 0.002], more commonly had a delta rhythm at ictal onset [OR = 3.67 (0.97-20.47), P = 0.057], and less frequently had histopathological evidence of HS [OR = 0 (0-0.85), P = 0.031]. There was no significant difference in surgical outcome despite half of those without HS having a hippocampal-sparing procedure. Based on the findings outlined, HS-ve PET-positive TLE may be a surgically remediable syndrome distinct from HS+ve TLE, with a pathophysiological basis that primarily involves lateral temporal neocortical rather than mesial temporal structures.

Relation between FIGO stage, primary tumor volume, and presence of lymph node metastases in cervical cancer patients referred for radiotherapy

The aims of this study were to determine, firstly, the relationship between FIGO stage and various tumor parameters determined by magnetic resonance imaging (MRI), and, secondly, whether any of these parameters were predictors of lymph node metastases as determined by fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) in cervical cancer patients referred for radiotherapy. In 70 consecutive patients, both PET and MRI visualized all primary tumors except for one previously removed by cone biopsy. While clinical diameter and MRI-derived diameter showed a significant relationship between these two measurements (r = 0.70; P < 0.001) there was a large variability in MRI diameter for each FIGO stage and wide overlap. The average volume of primary cervical tumor on MRI was 60 cc (5-256). In FIGO stages, I, II, III and IV, uterine body involvement was present in 58%, 73%, 88%, and 100% of 19, 30, 16, and 5 patients, respectively (Ptrend= 0.015). Node positivity on FDG PET was present in 11% of patients without uterine body extension, but increased to 75% in those with uterine involvement. Average tumor volume in node-negative patients was 49 cc (5-186). Average tumor volume in node-positive patients was 69 cc (8-256). There was a significant association between nodal involvement and both FIGO stage (P = 0.018) and uterine body involvement (P < 0.001), but tumor volume and longitudinal MRI diameter were not statistically significant in unifactor predictors of nodal involvement. In multivariate analysis only uterine body extension, however, was independently related to the risk of nodal involvement. In conclusion, MRI provides noninvasive tumor size evaluation and can also demonstrate invasion of the uterine body that appears to be associated with an increased risk of nodal metastasis. This may provide clinically important prognostic information not available from current FIGO staging.

A comparison of fluorine-18 fluoro-deoxyglucose PET and technetium-99m sestamibi in assessing patients with multiple myeloma

OBJECTIVE

The extent of disease in patients with multiple myeloma or related conditions may be difficult to assess. In previous small studies, both FDG-PET (PET) and Tc-99m sestamibi scans (MIBI) have identified sites of occult disease in myeloma.

METHODS

We reviewed the results for patients at our institution who have undergone PET and/or MIBI scans to assess myeloma. Concordance between the scans, ability to identify otherwise occult disease and impact on patient management was assessed.

RESULTS

Thirty-six patients had > or =1 PET scan, 56 had > or =1 MIBI scan and 23 had concurrent PET and MIBI scans. MIBI detected additional sites to skeletal survey in 38 of 56 (68%) cases. PET detected additional sites to skeletal survey in 18 of 36 (50%) cases. MIBI generally detected more disease sites than PET. PET and MIBI were concordant in eight of 23 (35%) cases. The percentage plasma cell infiltrate within the marrow correlated with the number of sites detected by MIBI, but not by PET. In 23 of 69 cases (33%), scan results impacted on management, particularly by upstaging disease at diagnosis and by recognising subsequent disease progression. The results were also helpful for evaluating the presence of ongoing disease activity in previously irradiated sites remaining abnormal on skeletal survey following treatment.

CONCLUSIONS

MIBI and PET are useful additional diagnostic tools for detecting otherwise occult sites of myeloma. The use of MIBI PET should particularly be considered in the evaluation of a patient with an early-stage plasma cell dyscrasia to exclude the presence of more extensive disease.

Relation between FIGO stage, primary tumor volume, and presence of lymph node metastases in cervical cancer patients referred for radiotherapy

The aims of this study were to determine, firstly, the relationship between FIGO stage and various tumor parameters determined by magnetic resonance imaging (MRI), and, secondly, whether any of these parameters were predictors of lymph node metastases as determined by fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) in cervical cancer patients referred for radiotherapy. In 70 consecutive patients, both PET and MRI visualized all primary tumors except for one previously removed by cone biopsy. While clinical diameter and MRI-derived diameter showed a significant relationship between these two measurements (r = 0.70; P < 0.001) there was a large variability in MRI diameter for each FIGO stage and wide overlap. The average volume of primary cervical tumor on MRI was 60 cc (5–256). In FIGO stages, I, II, III and IV, uterine body involvement was present in 58%, 73%, 88%, and 100% of 19, 30, 16, and 5 patients, respectively (Ptrend = 0.015). Node positivity on FDG PET was present in 11% of patients without uterine body extension, but increased to 75% in those with uterine involvement. Average tumor volume in node-negative patients was 49 cc (5–186). Average tumor volume in node-positive patients was 69 cc (8–256). There was a significant association between nodal involvement and both FIGO stage (P = 0.018) and uterine body involvement (P < 0.001), but tumor volume and longitudinal MRI diameter were not statistically significant in unifactor predictors of nodal involvement. In multivariate analysis only uterine body extension, however, was independently related to the risk of nodal involvement. In conclusion, MRI provides noninvasive tumor size evaluation and can also demonstrate invasion of the uterine body that appears to be associated with an increased risk of nodal metastasis. This may provide clinically important prognostic information not available from current FIGO staging.

Diffuse large B-cell non-Hodgkin's lymphoma presenting as Sister Joseph's nodule

Traditionally associated with intra-abdominal epithelial tumours, umbilical metastases (known eponymously as "Sister Joseph's nodules") are often thought to represent advanced malignancy with dismal prognosis. Lymphomas are rare causes of umbilical metastases, with no cases reported prior to 1966 and only three cases since. We describe a patient who presented with diffuse large B-cell non-Hodgkin's lymphoma with "signet ring" morphology manifesting as a "Sister Joseph's nodule", who had an excellent response to systemic therapy, with no detectable disease at 12 months post-completion of therapy. Our experience with this patient highlights the need for accurate histological diagnosis in all umbilical metastases, and dispels the widely held assumption that "Sister Joseph's nodules" represent disseminated malignancy beyond the realm of effective therapy. The patient's unusual histology and pattern of disease involvement are also discussed.

Solitary pulmonary nodules: accuracy and cost-effectiveness of sodium iodide FDG-PET using Australian data

This study uses Australian data to confirm the accuracy of dedicated sodium iodide (NaI) fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in evaluating indeterminate solitary pulmonary nodules (SPNs) and to determine the conditions under which PET could play a cost-effective role in this evaluation. Ninety-two patients from two Australian hospitals in different states underwent FDG-PET for evaluation of an SPN. Observed values for prior probability of malignancy and diagnostic accuracy of PET were applied to previously published decision tree models using published Australian health care costs. The accuracy of FDG-PET was 93% with a sensitivity of 92% and a specificity of 95%. The prior probability of malignancy (0.54), PET sensitivity and PET specificity indicated cost savings per patient of up to EUR 455 (Adollars 774) based on a PET cost of EUR 706 (Adollars 1,200). PET would remain cost-effective for levels of prior probability up to 0.8-0.9 and a PET cost of EUR 736-1,161 (Adollars 1,252-Adollars 1,974). It is concluded that NaI PET is accurate, cost saving and cost-effective for the characterisation of indeterminate pulmonary nodules in Australia. Comparison with previous reports from the United States confirms that FDG-PET can remain cost-effective despite population differences in medical costs, disease prevalence and PET diagnostic performance.

Display of positron emission tomography with Cadplan

Recent clinical experience at Peter MacCallum Cancer Institute (PMCI) with the use of unregistered Positron Emission Tomography (PET) images for radiotherapy target marking in the lung suggests that co-registered PET images would be invaluable. PMCI has three radiotherapy treatment planning systems but none of them currently is able to display or co-register PET images with Computed Tomography (CT) images. This paper details the approach taken to display co-registered PET images with the CADPLAN treatment planning system. CT Image files are normally transferred to Cadplan by DICOM transfer, but the Cadplan DICOM server will not receive (has no presentation context for) PET images. The fundamental design of the CADPLAN system envisages display of only a single image dataset, which must be a CT scan for planning reasons. The problem of data transfer is crudely solved by File Transfer Protocol (FTP) over the network. Fortunately the multislice format of the PET image files makes individual transfer manageable. A menu based C program running at the same time as Cadplan is invoked to sample the DICOM PET Image and create multiple Cadplan CART image format files that are co-registered with each existing transverse CT slice. With the Cadplan in contour mode, the program allows the co-registered PET images to be swapped in and out of the image section of the CART files promptly, while keeping the contour information. This allows radiotherapy target volumes to be marked using transverse PET emission images, and effectively circumvents the design constraints prohibiting the display of more than one image set. Contours can be over-laid for review on reconstructed sagittal or coronal views of CT or PET images constructed using the standard Cadplan tools. Co-registration is facilitated by identical positioning with the aid of lasers and FDG loaded fiducial markers on the PET scanner and CT couch. A polyurethane cast fixed with EFFILOCK is used to ensure identical patient orientation on the CT and PET couches. Since both imaging modalities are without significant geometric distortion the co-registration is then simply a translation. PET transmission images can be used for co-registration verification. The practical implementation of display of PET images with CADPLAN has enabled us to begin a trial of 10 patients, the results of which will be reported separately.

Performance of sodium iodide based (18)F-fluorodeoxyglucose positron emission tomography in the characterization of indeterminate pulmonary nodules or masses

The purpose of this study was to document the accuracy of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) with sodium iodide detectors in characterizing indeterminate lung nodules or masses and in identifying additional extra-lesional findings. 50 consecutive patients without a confident diagnosis of malignancy on CT underwent (18)FDG PET with and without attenuation correction. The diagnosis of malignancy was made using visual diagnostic criteria, and tumour-to-blood pool ratios were calculated. The final diagnosis was established by surgery, biopsy or long-term follow-up. Any additional findings made at PET were recorded and similarly verified. Using blinded visual diagnostic criteria for the differentiation of malignant from benign nodules, sodium iodide PET achieved a sensitivity of 91% (30 of 33 cases), a specificity of 88% (15 of 17 cases), a positive predictive value for malignancy of 94% (30 of 32 cases) and a negative predictive value of 83% (15 of 18 cases). False positives occurred with active tuberculosis and sarcoidosis. False negatives were a 3 cm bronchoalveolar carcinoma, a 1.3 cm sarcoma metastasis and a 1 cm carcinoma. Use of tumour-to-blood pool ratios did not improve performance. PET suggested the presence of nodal or distant metastases in 13 of 33 patients with a malignant pulmonary lesion. These PET findings were confirmed in 11 patients. These results indicate that sodium iodide PET is an accurate tool for the characterization of indeterminate pulmonary masses or nodules and simultaneously provides non-invasive staging information that can alter patient management in up to one-third of such patients. Performance of sodium iodide PET is comparable with reported results for PET scanners using other detector materials.