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Biomedical subjects

R J Hicks

Publications and source records attributed to R J Hicks.

At least 37 records · Page 2Linked to original sources
PubMed2001

Imaging with F-18 FDG PET is superior to Tl-201 SPECT in the staging of non-small cell lung cancer for radical radiation therapy.

Thallium-201 (Tl-201) single photon emission computed tomography (SPECT) is funded for evaluation of malignancy in Australia and may have utility for staging of non-small cell lung cancer (NSCLC) if CT results are equivocal. Fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET) is superior to CT for staging NSCLC but is more expensive and less widely available than Tl-201 SPECT. Therefore, these techniques were prospectively compared in 27 radical radiation therapy candidates. Patients were allocated a conventional, PET and Tl-201 stage. Tumour to background ratios (TBR) were recorded for the primary on both techniques. Metastatic disease was confirmed by surgical pathology, serial imaging or clinical follow up. Tumour to background ratios were consistently higher for FDG PET than Tl-201 SPECT (P < 0.0001). Positron emission tomography detected all known primary tumours but Tl-201 failed to image four primary tumours (15%). In 10 of 18 cases of discordance between PET and Tl-201 SPECT regarding stage, corroboration was available from pathology or disease progression. Positron emission tomography was shown to have a 100% positive predictive value, including all three patients with PET-detected distant metastases (P=0.002). Results indicate that PET is superior to Tl-201 SPECT scanning in the staging of NSCLC for radical radiation therapy, and that the low sensitivity for detection of local and metastatic disease is likely to limit the clinical impact and cost-effectiveness of this technique despite its lower cost.

Aged↗
PubMed2001

Cardiac blood-pool imaging in oncology more than an ejection fraction?

Cardiac function is commonly evaluated in patients with cancer in most nuclear medicine departments. At their dedicated cancer facility, the authors routinely perform a dynamic right anterior oblique first-pass study and a 4-minute left anterior oblique static planar study in addition to the routine equilibrium gated scanning in appropriate projections. Here they show the range of noncardiac disease encountered using this protocol. Useful unexpected information can be obtained from left ventricular ejection studies, and further data may be gained from these simple additions to this common test.

Abdomen↗
PubMed2001

Successful treatment of disseminated relapsed medulloblastoma in an infant by primary radiotherapy.

An infant who experienced disseminated relapse of medulloblastoma while receiving chemotherapy is described. He was subsequently treated with radiation therapy. Seven and one-half years from diagnosis, he is currently disease-free and enjoys a relatively normal life. We emphasize the importance of considering radiation as one of the treatment modalities for young children with relapsed medulloblastoma.

Cerebellar Neoplasms↗
PubMed2001

The utility of a 3-dimensional, large-field-of-view, sodium iodide crystal--based PET scanner in the presurgical evaluation of partial epilepsy.

UNLABELLED: (18)F-FDG PET is an accurate and reliable technique for localizing medically refractory temporal lobe epilepsy, but widespread use has been hindered by limited reimbursement in many countries because of the high cost of traditional PET equipment and radioisotopes. Additionally, the place of FDG PET as a cost-effective tool for presurgical evaluation of epilepsy has been questioned because of limited data showing that FDG PET provides localization information incremental to that provided by more established techniques, particularly MRI and ictal electroencephalography (EEG). Three-dimensional (3D), large-field-of-view, sodium iodide crystal-based scanners have lower equipment and running costs and better multiplanar resolution than traditional 2-dimensional bismuth germinate (BGO) systems but have not yet been validated for evaluation of epilepsy. Our purpose was to investigate the localization rate, accuracy, and prognostic value of FDG PET images acquired on a 3D, large-field-of-view, sodium iodide crystal-based PET scanner in the presurgical evaluation of intractable partial epilepsy. We also wanted to establish the incremental value of FDG PET over established MRI and ictal EEG techniques. METHODS: Fifty-five patients who were surgical candidates because of medically refractory partial epilepsy were examined. For most of these patients, the lesions had not been clearly localized on conventional assessment. The FDG PET scans were reviewed independently by 2 reviewers who were unaware of the patients' clinical details, ictal EEG findings, and volumetric MRI results, and the FDG PET results were correlated with those of MRI and EEG and with postsurgical outcome. RESULTS: Forty-two patients (76%) had localizing FDG PET images (37 temporal, 5 extratemporal). The ictal EEG recordings were localizing in 66%, and the MRI findings were localizing in 27% (which increased to 35% after the MRI findings were reviewed again after PET). Concordance between the site of the PET localizations and the site of the MRI or EEG localizations was 100%. The PET images were localizing in 63% and 69% of patients with nonlocalizing ictal EEG and MRI findings, respectively. Twenty-one of 24 patients who subsequently underwent epilepsy surgery had localizing FDG PET images; of these 21 patients, 18 (86%) had a class I outcome. Multiple regression analysis showed the FDG PET results to be predictive of postsurgical outcome independently of the MRI findings. CONCLUSION: For intractable partial epilepsy, FDG PET using a 3D, large-field-of-view, sodium iodide crystal-based scanner provided clinically useful localizing information that was at least as accurate as the results reported for traditional BGO-based scanners. The PET images provided prognostically significant localization information incremental to that provided by volumetric MRI and ictal EEG, particularly if 1 of these studies was nonlocalizing.

Adolescent↗
PubMed2001

Pattern of uptake and excretion of (18)F-FDG in the lactating breast.

UNLABELLED: Excretion of radiopharmaceuticals into breast milk poses a potential risk to infants and clear recommendations regarding interruption times are required. There are few data available regarding the impact of (18)F-FDG on this issue. With increasing use of PET for oncologic imaging and its potential advantages to nursing mothers because of its short physical half-life compared with other commonly used tumor imaging agents such as (67)Ga and (201)Tl, evaluation of the excretion pattern of this agent in breast milk is important. METHODS: We have evaluated the uptake of FDG in the breasts in 7 women, 6 of whom were lactating and 1 of whom was in early postpartum but had not commenced breast-feeding. Milk samples were obtained from 4 of the lactating women, including serial samples from 1. RESULTS: Significantly increased breast uptake was identified in all lactating breasts but not in 1 breast consistently refused by the nursing infant or in the woman who had not begun breast-feeding after delivery of her child. No qualitative change or semiquantitative estimate of radiotracer uptake in the breast was seen after expression of breast milk. Decay-corrected activity measurable in breast milk ranged from 5.54 to 19.3 Bq/mL/MBq injected. Using a standard model of breast-feeding, the calculated maximum cumulative dose to the infant, 0.085 mSv with no interruption of breast-feeding, is well below the recommended limit of 1 mSv. CONCLUSION: High uptake of FDG in the lactating breast appears to be related to suckling. There is, however, little secretion of activity into breast milk. Accordingly, a higher radiation dose is received by the infant from close contact with the breast than from ingestion of radioactive milk.

Adult↗
PubMed2001

(18)F-FDG PET provides high-impact and powerful prognostic stratification in staging newly diagnosed non-small cell lung cancer.

UNLABELLED: Survival of lung cancer patients remains poor despite increasingly aggressive treatment. Conventional staging has well-described limitations. (18)F-FDG PET has been shown to stage lung cancer more accurately than does CT scanning, but the impact on patient treatment and outcome is poorly defined. This study evaluated this impact in routine clinical practice within a tertiary oncology facility. METHODS: For 153 consecutive patients with newly diagnosed non-small cell lung cancer, the treatment plan based on conventional staging methods was compared with the treatment plan based on incorporation of PET findings. Survival was analyzed using the Cox proportional hazards regression model. RESULTS: For broad groupings of stage, 10% of cases were downstaged and 33% upstaged by PET. When assessable, the PET stage was confirmed in 89% of patients. PET had a high impact on 54 patients (35%), including 34 whose therapy was changed from curative to palliative, 6 whose therapy was changed from palliative to curative, and 14 whose treatment modality was changed but not the treatment intent. For 39 patients (25%), a previously selected therapy was altered because of the PET findings. The Cox model indicated that the pre-PET stage was significantly associated with survival (P = 0.013) but that the post-PET stage provided much stronger prognostic stratification (P < 0.0001) and remained significant after adjustment for treatment delivered. CONCLUSION: Staging that incorporated PET provided a more accurate prognostic stratification than did staging based on conventional investigations. Further, the additional information provided by PET significantly and appropriately changed management in the majority of patients.

Aged↗
PubMed2001

The utility of (18)F-FDG PET for suspected recurrent non-small cell lung cancer after potentially curative therapy: impact on management and prognostic stratification.

UNLABELLED: After potentially curative therapy of non-small cell lung cancer (NSCLC), masses or symptoms suggestive of relapse are common but may be difficult to characterize. Early detection is important because salvage therapies are available for localized recurrence. This study evaluated whether (18)F-FDG PET is useful and predictive of outcome in this setting. METHODS: For 63 consecutive patients with suspected relapse >6 mo after definitive treatment of NSCLC, the apparent extent of disease on conventional restaging was compared with that on FDG PET. Patients with already confirmed systemic metastases were excluded unless locally aggressive treatment of these was being considered. Serial imaging and pathologic results were obtained during a median follow-up of 19 mo to validate diagnostic findings. Prognostic significance was tested using the Cox proportional hazards regression model. RESULTS: PET had positive findings in 41 of 42 patients with confirmed relapse (sensitivity, 98%). No disease was evident during a minimum follow-up of 12 mo in 14 of 15 patients with clinically suspected relapse but negative PET findings (negative predictive value, 93%). PET induced a major management change in 40 patients (63%), including 6 whose treatment was changed from curative to palliative, 3 whose treatment was changed from palliative to curative, and 9 for whom negative PET findings prevented active management. Both the presence (P = 0.012) and the extent (P < 0.0001) of relapse on PET were highly significant prognostic factors. There was also significant prognostic stratification based on the treatment delivered after the PET study (P = 0.011), but after adjustment for this treatment, PET status remained highly predictive of survival. CONCLUSION: PET better assesses the status of disease and stratifies prognosis than does conventional staging, affects patient management, and should be incorporated into paradigms for suspected recurrence of NSCLC.

Aged↗
PubMed2000

Intravenous extension of lung carcinoma to the left atrium: demonstration by positron emission tomography with CT correlation.

Intravenous extension of lung carcinoma is rare. A right upper lobe bronchogenic carcinoma with unusually elongated intravenous extension to the left atrium was first visualized with positron emission tomography (PET) and then confirmed with dynamic CT. The PET appearance of intravascular tumour spread is striking, and presents only a short differential diagnosis.

Carcinoma, Non-Small-Cell Lung↗
PubMed2000

Prokinetic effects of erythromycin on the ileum, cecum, and pelvic flexure of horses during the postoperative period.

OBJECTIVE: To evaluate the effect of erythromycin on motility of the ileum, cecum, and pelvic flexure of horses during the postoperative and post-recovery periods. ANIMALS: 8 healthy adult horses. PROCEDURE: Horses were anesthetized and bipolar electrodes were implanted in smooth muscle of the ileum, cecum, and pelvic flexure. Approximately 4, 16, and 24 hours (postoperative recording sessions) and at least 8 days (post-recovery recording session) after surgery, myoelectric activity was recorded before and after administration of erythromycin (0.5 mg/kg). RESULTS: Following erythromycin administration, myoelectric activity was increased in the ileum during all postoperative recording sessions but not during the post-recovery recording session. Myoelectric activity was increased in the cecum following erythromycin administration only during the post-recovery recording session. Myoelectric activity was increased in the pelvic flexure following erythromycin administration during all recording sessions. During several recording sessions, there were short periods during which myoelectric activity was significantly decreased following erythromycin administration. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that erythromycin has an effect on myoelectric activity of the ileum, cecum, and pelvic flexure in horses; however, prokinetic effects of erythromycin administered during the postoperative period were not always the same as effects obtained when the drug was administered after horses had recovered from the effects of surgical implantation of recording devices. Therefore, caution must be exercised when extrapolating results of prokinetic studies in healthy animals to animals with abnormal gastrointestinal tract motility.

Animals↗
PubMed1999

Positron emission tomography (PET): experience with a large-field-of-view three-dimensional PET scanner.

Positron emission tomography (PET) using fluorine-18 fluorodeoxyglucose (FDG) is an accurate technique for staging and therapeutic monitoring in oncology. We evaluated our use of FDG PET in an oncology centre after our first 2500 studies, and summarise our experience of PET for the major referral indications. Optimised for clinical service, PET offers lower scanning costs and therefore improved cost-effectiveness.

Cost-Benefit Analysis↗
PubMed1998

Surgery for primary hyperparathyroidism 1962-1996: indications and outcomes.

OBJECTIVE: To examine changes over the past three decades in the indications for, and outcomes of, surgery for primary hyperparathyroidism. DESIGN: Survey of a prospective hospital database. SETTING: Royal North Shore Hospital (a tertiary referral and university teaching hospital), Sydney, New South Wales, January 1962 to December 1996. PATIENTS: All 733 patients who underwent neck exploration for primary hyperparathyroidism. RESULTS: The annual number of parathyroidectomies increased virtually exponentially, from a mean of two in 1962-1969 to 73 in 1996. In the 1960s and 1970s, the most common indication for surgery was the presence of renal calculi (58% and 43%, respectively), but in the 1980s there was a marked increase in presentation of asymptomatic disease after biochemical screening (19%). In the 1990s, low bone mineral density detected by osteodensitometry has become the most common indication for surgery (31%). After initial operation, 11 patients (2%) had persistent hypercalcaemia, with five of these cured by reoperation--an overall failure rate of 1%. CONCLUSIONS: Surgery for primary hyperparathyroidism has become increasingly common, with low bone mineral density replacing renal calculi as the most common indication for surgery. Neck exploration in experienced hands results in an overall cure rate of 99%.

Adolescent↗
PubMed1997

Nuclear medicine techniques provide unique physiologic characterization of suspected and known soft tissue and bone sarcomas.

Primary bone and soft tissue tumors have a range of physiologic, biochemical and genetic characteristics which differentiate them from benign tumors and normal tissues. These "fingerprints" are amenable to noninvasive detection and quantification using nuclear medicine techniques. Functional characterization using radiotracers imaged using a gamma camera or positron emission tomography (PET) can provide unique but complementary information to that provided by anatomically-based imaging modalities such as plain radiography, computed tomography (CT) and magnetic resonance imaging (MRI). This is particularly important following therapy when residual mass lesions may cause a dilemma regarding the need for further treatment. Lack of understanding of the role of functional imaging has impeded more rational use of nuclear medicine in this field. This review addresses the role of nuclear medicine techniques in the primary evaluation, staging, and therapeutic monitoring of soft tissue and bone sarcomas. The potential of delivering targeted radiotherapy to these tumors with radiopharmaceuticals which exploit the unique pathophysiology of each individual malignant lesion is also addressed.

Bone Neoplasms↗
PubMed1996

Prediction of outcome after revascularization in patients with poor left ventricular function.

BACKGROUND: In patients with poor left ventricular function, the determinants of outcome after revascularization are unknown. METHODS: We studied prospectively 57 patients with stable coronary artery disease and poor left ventricular function (left ventricular ejection fraction, 0.28 +/- 0.04) who underwent coronary artery bypass grafting. Clinical variables were assessed as predictors of outcome in all patients, and preoperative stress thallium-201 scintigraphic data were analysed in 37 patients. RESULTS: The operative mortality was 1.7%. At 12 months after operation, 46 of the 49 survivors were angina-free and 35 had fewer heart failure symptoms, but postoperative left ventricular ejection fraction (0.30 +/- 0.09) did not change significantly. Eighteen survivors had left ventricular ejection fraction improved by 0.05 or more (0.30 +/- 0.03 preoperatively, 0.40 +/- 0.05 postoperatively; p = 0.0001). The adjusted odds ratio of large reversible thallium-201 defects in predicting such outcome was 15 (95% confidence interval, 1.6 to 140), whereas other clinical variables had no predictive value. The transplantation-free 5-year survival was 73%. CONCLUSIONS: In patients with poor left ventricular function, surgical revascularization can be performed safely, with good symptomatic relief and long-term survival. One-year survival and improvement in left ventricular function is better in patients with large reversible defects on preoperative stress thallium-201 scintigraphy.

Aged↗
PubMed1996

Radiosynthesis of [123I]N-methyl-4-iododexetimide and [123I]N-methyl-4-iodolevetimide: in vitro and in vivo characterisation of binding to muscarinic receptors in the rat heart.

[123I]N-methyl-4-iododexetimide, [123I]MIDEX, and its pharmacologically inactive enantiomer [123I]N-methyl-4-iodolevetimide, [123I]MILEV were prepared via electrophilic iododesilylation using Chloramine-T as oxidising agent followed by N-methylation using methyl iodide. The radiotracers were purified with semi-preparative HPLC with radiochemical yields of 80 +/- 11% (n = 6). The average time of synthesis was 100 min with specific activity > 2000 Ci/mmol. In vitro, the binding of [123I]MIDEX, after addition of carrier, measured on homogenates of rat atrium was Bmax = 4.5 +/- 0.4 pmol/mg protein, Kd = 3.3 +/- 0.2 nM while in the ventricle Bmax = 2.3 +/- 0.2 pmol/mg protein, Kd = 4.0 +/- 1.4 nM. In vitro, the binding of [123I]MILEV was non-specific. The in vivo biodistribution of [123I]MIDEX showed high uptake in the atrium (3.2% ID/g) and left and right ventricles (2.2, 2.5% ID/g respectively) at 5 min followed by clearance. High heart-to-lung and moderate liver-to-lung ratios were obtained during 60 min. Radioactivity in the atrium and ventricles was reduced by pre-administration of the m-AChR antagonist MQNB (1 mg/kg). Pretreatment of rats with other m-AChR ligands, pirenzapine (M1), methoctramine (M2) and 4-DAMP (M3) also resulted in reduction of [123I]MIDEX uptake with methoctramine being the most potent. [123I]MIDEX distribution in the rat heart was not significantly inhibited by pre-administration of selective adrenergic drugs. The uptake was highly stereoselective since the inactive enantiomer, [123I]MILEV, demonstrated very low myocardial retention. The stability of [123I]MIDEX was evaluated by performing a metabolite study on atrium samples which revealed unchanged radiotracer 60 min postinjection. These results suggest that [123I]MIDEX may be a useful single photon agent for in vivo imaging of myocardial m-AChR in humans with [123I]MILEV offering the potential of assessing non-specific binding of the active tracer.

Animals↗
PubMed1996

Impact of complementary parathyroid scintigraphy and ultrasonography on the surgical management of hyperparathyroidism.

BACKGROUND: An ongoing debate exists regarding the relative merits of full versus limited neck exploration in the surgical management of parathyroid adenomata. The aim of this study was to assess the impact of localization studies on the subsequent surgical management of hyperparathyroidism. METHODS: The accuracy of complementary ultrasonography and 201TI/99mTc parathyroid subtraction scintigraphy in hyperparathyroidism was evaluated retrospectively during a 10-year period in patients referred for localization studies. Surgical and pathologic confirmation of the diagnosis was possible in 121 patients, and these data formed the basis of this study. Operative procedure, times, outcome, and complications were recorded. RESULTS: The sensitivity, specificity, and accuracy for combined scintigraphy and ultrasonography were 86%, 98%, and 96%, respectively. Limited neck exploration was performed in 61 of 121 patients, and 60 patients underwent full neck exploration. In primary hyperparathyroidism 59 of 105 patients underwent limited and 46 underwent full neck exploration with average operative times of 70 and 109 minutes, respectively. (p < 0.0001). Complications developed in five patients who underwent full neck exploration. CONCLUSIONS: Confident localization of parathyroid adenomata facilitated successful limited neck exploration in most of the patients, questioning the need for full neck exploration in all patients with primary hyperparathyroidism.

Adenoma↗