H R Maxon

Queensland Institute of Medical Research, Brisbane, Queensland, Australia

Are you H R Maxon?

Claim your profile

Publications (75)486.15 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Serum thyrotropin (TSH) concentration and thyroid autoimmunity may be of prognostic importance in differentiated thyroid cancer (DTC). Preoperative serum TSH level has been associated with higher DTC stage in cross-sectional studies; data are contradictory on the significance of thyroid autoimmunity at the time of diagnosis. Objective: We sought to assess whether preoperative serum TSH and perioperative anti-thyroglobulin antibodies (TgAb) were associated with thyroid cancer stage and outcome in DTC patients followed by the National Thyroid Cancer Treatment Cooperative Study, a large multicenter thyroid cancer registry. Methods: Patients registered after 1996 with available preoperative serum TSH (n=617; the TSH cohort) or perioperative TgAb status (n=1770; the TgAb cohort) were analyzed for tumor stage, persistent disease, recurrence, and overall survival (OS) (median follow-up 5.5 years). Parametric tests assessed log transformed TSH, and categorical variables were tested with χ2. Disease-free survival (DFS) and OS was assessed with Cox models. Results: Geometric mean serum TSH levels were higher in patients with higher stage disease (stage III/IV=1.48 vs. 1.02 mU/L for stages I/II; P=0.006). The relationship persisted in those aged ≥45 years after adjusting for gender (P=0.01). Gross extrathyroidal extension (P=0.03) and presence of cervical lymph node metastases (P=0.003) were also significantly associated with higher serum TSH. Disease recurrence and all-cause mortality occurred in 37 and 38 TSH cohort patients respectively, which limited the power for survival analysis. Positive TgAb was associated with lower stage on univariate analysis (positive TgAb in 23.4% vs. 17.8% of stage I/II vs. III/IV patients, respectively; P=0.01), although the relationship lost significance when adjusting for age and gender (P=0.34). Perioperative TgAb was not an independent predictor of DFS (hazard ratio [HR]=1.12 [95%CI=0.74-1.69]) or OS (HR=0.98 [95%CI=0.56-1.72]). Conclusions: Preoperative serum TSH level is associated with higher DTC stage, gross extrathyroidal extension, and neck node metastases. Perioperative TgAb is not an independent predictor of DTC prognosis. A larger cohort is required to assess whether preoperative serum TSH level predicts recurrence or mortality.
    Thyroid: official journal of the American Thyroid Association 06/2013; · 2.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Thyroid cancer predominately affects women, carries a worse prognosis in older age, and may have higher mortality in men. Superimposed on these observations is the fact that most women have attained menopause by age 55 yr. The objective of the study was to determine whether men contribute disproportionately to papillary thyroid cancer (PTC) mortality or whether menopause affects PTC prognosis. Gender-specific mortality was normalized using age-matched subjects from the U.S. population. Multivariate Cox proportional hazard regression models incorporating gender, age, and National Thyroid Cancer Treatment Cooperative Study Group stage were used to model disease-specific survival (DSS). Patients were followed in a prospective registry. The relationships between gender, age, and PTC outcomes were analyzed. The unadjusted hazard ratio (HR) for DSS for women was 0.40 [confidence interval (CI) 0.24-0.65]. This female advantage diminished when DSS was adjusted for age at diagnosis and stage with a HR encompassing unity (HR 0.72, CI 0.44-1.19). Additional multivariate models of DSS considering gender, disease stage, and various age groupings showed that the DSS for women diagnosed at under 55 yr was improved over men (HR 0.33, CI 0.13-0.81). However, the HR for DSS increased to become similar to men for women diagnosed at 55-69 yr (HR 1.01, CI 0.42-2.37) and at 70 yr or greater (HR 1.17, CI 0.48-2.85). Although the overall outcome of women with PTC is similar to men, subgroup analysis showed that this composite outcome is composed of two periods with different outcomes. The first period is a period with better outcomes for women than men when the diagnosis occurs at younger than 55 yr; the second is a period with similar outcomes for both women and men diagnosed at ages greater than 55 yr. These data raise the question of whether an older age cutoff would improve current staging systems. We hypothesize that older age modifies the effect of gender on outcomes due to menopause-associated hormonal alterations.
    The Journal of clinical endocrinology and metabolism 04/2012; 97(6):E878-87. · 6.50 Impact Factor
  • Kyuran A. Choe, Harry R. Maxon
    [Show abstract] [Hide abstract]
    ABSTRACT: In an extensive review of this subject, 1095/3083 (35.5%) patients with papillary carcinoma and 102/797 (12.8%) patients with follicular carcinoma were found to have lymph node metastases at the time of initial diagnosis of their cancer (1). In children, the prevalence may be as high as 70% (2). Of patients thought to be disease free after their initial treatment, 252/2684 (9.4%) with papillary and 43/641 (6.7%) with follicular carcinoma subsequently developed nodal metastases (1).
    07/2011: pages 207-232;
  • James Brierley, Harry R. Maxon
    [Show abstract] [Hide abstract]
    ABSTRACT: For over 50 years, radioiodine-131 has been used in the post surgical treatment of differentiated thyroid cancer (1). In 1957, workers at the University of Michigan popularized 131I in an easy to use, empiric approach that recommended the administration of fixed activities of 131I to patients who were allowed to become hypothyroid after their initial surgical therapy (2). It soon became evident that only about 70-80% of differentiated thyroid cancers would concentrate 131I under these conditions (3). When patients whose recurrent/metastatic cancers could not be shown to concentrate 131I on diagnostic 131I scans were excluded, then 131I therapy given to the point of “ablation” of 131I uptake on subsequent diagnostic scans resulted in a significant improvement in mortality (4). The methods of patient preparation and treatment that were developed during the first 25 years of 131I use have not been modified in most health care facilities. In part this has been due to a shift in physician training. During the first 25 years, about 80% of nuclear medicine physicians entered the field from backgrounds in internal medicine, resulting in interest and training both in diseases of the thyroid and in the use of radioactive medicine by radiologists who are interested primarily in image interpretation or by endocrinologists who are not broadly trained in the intricacies of the use of radioactive materials, both of which groups find the decades old empiric approaches convenient to use.
    02/2011: pages 285-317;
  • Thyroid: official journal of the American Thyroid Association 11/2010; 20(12):1423-4. · 2.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Despite very low mortality associated with micropapillary thyroid cancer, locoregional recurrence is common and controversy exists regarding optimal surgical treatment and the role of adjunctive radioiodine. The National Thyroid Cancer Treatment Cooperative Study Group Registry was analyzed for recurrences in patients with unifocal versus multifocal micropapillary cancer, with or without nodal disease, depending upon the extent of surgery and the use of adjunctive radioiodine. Six hundred eleven patients considered disease-free after initial therapy were followed for 2572 person-years. Thirty patients (6.2%) had recurrences detected at a mean 2.8 years after primary treatment. Recurrences did not differ between patients with unifocal and multifocal disease overall; however, among patients who received less than a near-total thyroidectomy (NTT), those with multifocal disease had more recurrences than those with unifocal disease (18% vs. 4%, p = 0.01). Patients with multifocal disease who had a total (T) or NTT trended toward fewer recurrences than those undergoing less than an NTT (6% vs. 18%, p = 0.058). In patients who did not receive radioiodine therapy, recurrence was more common in patients with multifocal disease versus unifocal disease (7% vs. 2%, p = 0.02). However, radioiodine did not reduce recurrences in patients with multifocal disease or patients with positive nodes. Patients with positive nodes had more recurrences than node-negative patients regardless of surgical extent or use of radioiodine. Patients with micropapillary multifocal disease have a reduced risk of recurrence after a T/NTT compared with less surgery. A randomized, controlled trial is necessary and feasible to determine if radioiodine ablation of thyroid remnants is advantageous in patients with intrathyroidal micropapillary cancer.
    Thyroid: official journal of the American Thyroid Association 09/2009; 19(10):1043-8. · 2.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This analysis was performed to determine the effect of initial therapy on the outcomes of thyroid cancer patients. The study setting was a prospectively followed multi-institutional registry. Patients were stratified as low risk (stages I and II) or high risk (stages III and IV). Treatments employed included near-total thyroidectomy, administration of radioactive iodine, and thyroid hormone suppression therapy. Outcome measures were overall survival, disease-specific survival, and disease-free survival. Near-total thyroidectomy, radioactive iodine, and aggressive thyroid hormone suppression therapy were each independently associated with longer overall survival in high-risk patients. Near-total thyroidectomy followed by radioactive iodine therapy, and moderate thyroid hormone suppression therapy, both predicted improved overall survival in stage II patients. No treatment modality, including lack of radioactive iodine, was associated with altered survival in stage I patients. Based on our overall survival data, we confirm that near-total thyroidectomy is indicated in high-risk patients. We also conclude that radioactive iodine therapy is beneficial for stage II, III, and IV patients. Importantly, we show for the first time that superior outcomes are associated with aggressive thyroid hormone suppression therapy in high-risk patients, but are achieved with modest suppression in stage II patients. We were unable to show any impact, positive or negative, of specific therapies in stage I patients.
    Thyroid 01/2007; 16(12):1229-42. · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Recombinant human TSH has been developed to facilitate monitoring for thyroid carcinoma recurrence or persistence without the attendant morbidity of hypothyroidism seen after thyroid hormone withdrawal. The objectives of this study were to compare the effect of administered recombinant human TSH with thyroid hormone withdrawal on the results of radioiodine whole body scanning (WBS) and serum thyroglobulin (Tg) levels. Two hundred and twenty-nine adult patients with differentiated thyroid cancer requiring radioiodine WBS were studied. Radioiodine WBS and serum Tg measurements were performed after administration of recombinant human TSH and again after thyroid hormone withdrawal in each patient. Radioiodine whole body scans were concordant between the recombinant TSH-stimulated and thyroid hormone withdrawal phases in 195 of 220 (89%) patients. Of the discordant scans, 8 (4%) had superior scans after recombinant human TSH administration, and 17 (8%) had superior scans after thyroid hormone withdrawal (P = 0.108). Based on a serum Tg level of 2 ng/mL or more, thyroid tissue or cancer was detected during thyroid hormone therapy in 22%, after recombinant human TSH stimulation in 52%, and after thyroid hormone withdrawal in 56% of patients with disease or tissue limited to the thyroid bed and in 80%, 100%, and 100% of patients, respectively, with metastatic disease. A combination of radioiodine WBS and serum Tg after recombinant human TSH stimulation detected thyroid tissue or cancer in 93% of patients with disease or tissue limited to the thyroid bed and 100% of patients with metastatic disease. In conclusion, recombinant human TSH administration is a safe and effective means of stimulating radioiodine uptake and serum Tg levels in patients undergoing evaluation for thyroid cancer persistence and recurrence.
    Journal of Clinical Endocrinology &amp Metabolism 12/1999; 84(11):3877-85. · 6.43 Impact Factor
  • H R Maxon
    [Show abstract] [Hide abstract]
    ABSTRACT: Radioiodine-131 imaging is the traditional method of detecting residual or recurrent differentiated thyroid cancer. The stimulation of such tissues to take up radioiodine may be achieved either by complete cessation of thyroid hormone, by partial thyroid hormone withdrawal, or by the administration of recombinant human thyrotropin (TSH). Complete or partial thyroid hormone withdrawal may result in serum TSH concentrations adequate for radioiodine imaging in up to 90% of patients. When known or suspected recurrent or metastatic disease is not evident on radioiodine imaging, single photon emission tomographic imaging with either thallium-201 chloride or technetium-99m-MIBI compounds may detect up to 80%-90% of cancers at least 1 to 1.5 cm in size, although specificity is less than with 131I. Fluorine-18-FDG positron emission tomography is a somewhat less available but acceptable substitute for thallium-201 or 99mTc-MIBI imaging. Tumor foci that concentrate either TI-201 or 18FDG intensely with little or no 131I uptake appear to behave more aggressively than those concentrating 131I avidly.
    Thyroid 06/1999; 9(5):443-6. · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Treatment of differentiated thyroid cancer has been studied for many years, but the benefits of extensive initial thyroid surgery and the addition of radioiodine therapy or external radiation therapy remain controversial. To determine the relations among extent of surgery, radioiodine therapy, and external radiation therapy in the treatment of high-risk papillary and non-Hürthle-cell follicular thyroid carcinoma. Analysis of data from a multicenter study. 14 institutions in the United States and Canada participating in the National Thyroid Cancer Treatment Cooperative Study Registry. 385 patients with high-risk thyroid cancer (303 with papillary carcinoma and 82 with follicular carcinoma). Death, disease progression, and disease-free survival. Total or near-total thyroidectomy was done in 85.3% of patients with papillary carcinoma and 71.3% of patients with follicular cancer. Overall surgical complication rate was 14.3%. Total or near-total thyroidectomy improved overall survival (risk ratio [RR], 0.37 [95% CI, 0.18 to 0.75]) but not cancer-specific mortality, progression, or disease-free survival in patients with papillary cancer. No effect of extent of surgery was seen in patients with follicular thyroid cancer. Postoperative iodine-131 was given to 85.4% of patients with papillary cancer and 79.3% of patients with follicular cancer. In patients with papillary cancer, radioiodine therapy was associated with improvement in cancer-specific mortality (RR, 0.30 [CI, 0.09 to 0.93 by multivariate analysis only]) and progression (RR, 0.30 [CI, 0.13 to 0.72]). When tall-cell variants were excluded, the effect on outcome was not significant. After radioiodine therapy, patients with follicular thyroid cancer had improvement in overall mortality (RR, 0.17 [CI, 0.06 to 0.47]), cancer-specific mortality (RR, 0.12 [CI, 0.04 to 0.42]), progression (RR, 0.21 [CI, 0.08 to 0.56]), and disease-free survival (RR, 0.29 [CI, 0.08 to 1.01]). External radiation therapy to the neck was given to 18.5% of patients and was not associated with improved survival, lack of progression, or disease-free survival. This study supports improvement in overall and cancer-specific mortality among patients with papillary and follicular thyroid cancer after postoperative iodine-131 therapy. Radioiodine therapy was also associated with improvement in progression in patients with papillary cancer and improvement in progression and disease-free survival in patients with follicular carcinoma.
    Annals of internal medicine 11/1998; 129(8):622-7. · 13.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The ideal therapy for differentiated thyroid cancer is uncertain. Although thyroid hormone treatment is pivotal, the degree of thyrotropin (TSH) suppression that is required to prevent recurrences has not been studied in detail. We have examined the relation of TSH suppression to baseline disease characteristics and to the likelihood of disease progression in a cohort of thyroid cancer patients who have been followed in a multicenter thyroid cancer registry that was established in 1986. The present study describes 617 patients with papillary and 66 patients with follicular thyroid cancer followed annually for a median of 4.5 years (range 1-8.6 years). Cancer staging was assessed using a staging scheme developed and validated by the registry. Cancer status was defined as no residual disease; progressive disease at any follow-up time; or death from thyroid cancer. A mean TSH score was calculated for each patient by averaging all available TSH determinations, where 1 = undetectable TSH; 2 = subnormal TSH; 3 = normal TSH; and 4 = elevated TSH. Patients were also grouped by their TSH scores: group 1: mean TSH score 1.0-1.99; group 2: mean TSH score 2.0-2.99; group 3: mean TSH score 3.0-4.0. The degree of TSH suppression did not differ between papillary and follicular thyroid cancer patients. However, TSH suppression was greater in papillary cancer patients who were initially classified as being at higher risk for recurrence. This was not the case for follicular cancer patients, where TSH suppression was similar for all patients. For all stages of papillary cancer, a Cox proportional hazards model showed that disease stage, patient age, and radioiodine therapy all predicted disease progression, but TSH score category did not. However, TSH score category was an independent predictor of disease progression in high risk patients (p = 0.03), but was no longer significant when radioiodine therapy was included in the model (p = 0.09). There were too few patients with follicular cancer for multivariate analysis. These data suggest that physicians use greater degrees of TSH suppression in higher risk papillary cancer patients. Our data do not support the concept that greater degrees of TSH suppression are required to prevent disease progression in low-risk patients, but this possibility remains in high-risk patients. Additional studies with more patients and longer follow-up may provide the answer to this important question.
    Thyroid 10/1998; 8(9):737-44. · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel prognostic staging classification encompassing all forms of thyroid carcinoma was created for the National Thyroid Cancer Treatment Cooperative Study (NTCTCS) Registry, with the goal of prospective validation and comparison with other available staging classifications. Patient information was recorded prospectively from 14 institutions. Clinicopathologic staging was based on patient age at diagnosis, tumor histology, tumor size, intrathyroidal multifocality, extraglandular invasion, metastases, and tumor differentiation. Between 1987 and 1995, 1607 patients were registered. Approximately 43% of patients were classified as NTCTCS Stage I, 24% Stage II, 24% Stage III, and 9% Stage IV. Patients with follicular carcinoma were more likely to have "high risk" Stage III or IV disease than those with papillary carcinoma. Of 1562 patients for whom censored follow-up was available (median follow-up, 40 months), 78 died of thyroid carcinoma or complications of its treatment. Five-year product-limit patient disease specific survival was 99.8% for Stage I, 100% for Stage II, 91.9% for Stage III, and 48.9% for Stage IV (P < 0.0001). The frequency of remaining disease free also declined significantly with increasing stage (94.3% for Stage I, 93.1%for Stage II, 77.8% for Stage III, and 24.6% for Stage IV). The same patients also were staged applying six previously published classifications as appropriate for their tumor type. The predictive value of the NTCTCS Registry staging classification consistently was among the highest for disease specific mortality and for remaining disease free, regardless of the tumor type. The NTCTCS Registry staging classification provides a prospectively validated scheme for predicting short term prognosis for patients with thyroid carcinoma.
    Cancer 09/1998; 83(5):1012-21. · 5.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Rhenium-188 (tin) hydroxyethylidine diphosphonate [188Re(Sn)HEDP] is a new radiopharmaceutical that localizes in skeletal metastases and emits beta particles that may be therapeutically beneficial. It was evaluated by in vitro and in vivo testing in the laboratory, in animals and in humans using 188Re from a variety of sources. It may be produced by a desk-top method developed previously for 186Re(Sn)HEDP using 188Re produced through neutron irradiation of either enriched 187Re or naturally occurring rhenium targets or the use of a 188W/188Re generator. So long as the mass of rhenium in the 188Re-perrhenate to be processed into 188Re(Sn)HEDP is at least 100 microg, satisfactory radiochemical yields and purity may be obtained by all methods. The 188Re(Sn)HEDP has biodistribution and radiation dosimetry characteristics that are similar to those noted previously for 186Re(Sn)HEDP and appears to result in similar benefits and toxicities in patients with skeletal metastases. External radiation exposure monitoring indicates that, only 4 hr after a therapeutic administration of 1110 MBq (30 mCi) of 188Re(Sn)HEDP, average exposure rates at 1 meter from the patient would be only 0.5 mR/hr. Same-day, on-demand, outpatient therapy of disseminated skeletal metastases appears to be feasible with 188Re(Sn)HEDP.
    Journal of Nuclear Medicine 04/1998; 39(4):659-63. · 5.77 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Context.— High-dose iodine 131 is the treatment of choice in the United States for most adults with hyperthyroid disease. Although there is little evidence to link therapeutic 131I to the development of cancer, its extensive medical use indicates the need for additional evaluation.Objective.— To evaluate cancer mortality among hyperthyroid patients, particularly after 131I treatment.Design.— A retrospective cohort study.Setting.— Twenty-five clinics in the United States and 1 clinic in England.Patients.— A total of 35,593 hyperthyroid patients treated between 1946 and 1964 in the original Cooperative Thyrotoxicosis Therapy Follow-up Study; 91% had Graves disease, 79% were female, and 65% were treated with 131I.Main Outcome Measure.— Standardized cancer mortality ratios (SMRs) after 3 treatment modalities for hyperthyroidism.Results.— Of the study cohort, 50.5% had died by the end of follow-up in December 1990. The total number of cancer deaths was close to that expected based on mortality rates in the general population (2950 vs 2857.6), but there was a small excess of mortality from cancers of the lung, breast, kidney, and thyroid, and a deficit of deaths from cancers of the uterus and the prostate gland. Patients with toxic nodular goiter had an SMR of 1.16 (95% confidence interval [CI], 1.03-1.30). More than 1 year after treatment, an increased risk of cancer mortality was seen among patients treated exclusively with antithyroid drugs (SMR, 1.31; 95% CI, 1.06-1.60). Radioactive iodine was not linked to total cancer deaths (SMR, 1.02; 95% CI, 0.98-1.07) or to any specific cancer with the exception of thyroid cancer (SMR, 3.94; 95% CI, 2.52-5.86).Conclusions.— Neither hyperthyroidism nor 131I treatment resulted in a significantly increased risk of total cancer mortality. While there was an elevated risk of thyroid cancer mortality following 131I treatment, in absolute terms the excess number of deaths was small, and the underlying thyroid disease appeared to play a role. Overall, 131I appears to be a safe therapy for hyperthyroidism. Figures in this Article HYPERTHYROID DISEASE is relatively common, particularly among women. The incidence of Graves disease, the cause of over 80% of hyperthyroidism in the United States, is between 0.02% and 1%.1- 3 Hyperthyroidism can be treated with radioiodine (iodine 131), surgery (subtotal thyroidectomy), or antithyroid drugs, but 131I is the treatment of choice for most adults in the United States.4 The extensive use of 131I therapy has raised concern regarding its potential carcinogenic and leukemogenic effects, although there is little evidence to support this concern.5- 9 Public interest in the late health effects of 131I exposure was rekindled by the 1986 Chernobyl accident and acknowledgment of past 131I releases from nuclear reactors and bomb testing. The Cooperative Thyrotoxicosis Therapy Follow-up Study began in 1961. It included 35609 patients with hyperthyroidism treated between 1946 and 1964 at one of 26 study clinics. When the study ended in 1968, after a mean follow-up of 8.2 years, thyroid cancer incidence and mortality10 and leukemia incidence5 were not significantly elevated in the 131I-treated patients compared with other patients. In a more recent follow-up of patients from the Mayo Clinic, Rochester, Minn, and Massachusetts General Hospital, Boston, total cancer mortality was not associated with131 I therapy.11- 12 However, the incidence of cancers in organs that concentrate iodine was elevated (relative risk [RR], 1.8; 95% confidence interval [CI], 1.1-3.2) among the 131 I-treated patients at the Mayo Clinic,13 and breast cancer incidence was slightly increased (RR, 1.3; 95% CI, 0.8-1.9) in the Massachusetts General Hospital patients.14 Although no association between 131I exposure and mortality from leukemia (standardized mortality ratio [SMR], 0.98; 95% CI, 0.64-1.42) or breast cancer (SMR, 0.86; 95% CI, 0.69-1.02) was seen among Swedish hyperthyroid patients, a significant excess of respiratory (SMR, 1.26; 95% CI, 1.04-1.49) and digestive (SMR, 1.14; 95% CI, 1.03-1.25) cancer mortality was observed. During the first 10 years of follow-up, there was an excess of thyroid cancer mortality (SMR, 3.22; 95% CI, 1.54-5.98), which completely disappeared after 10 years (SMR, 0.66; 95% CI, 0.08-2.37).15 To assess the long-term carcinogenic effects of treatment for hyperthyroidism, we conducted a mortality follow-up, through 1990, of the original Cooperative Thyrotoxicosis Therapy Follow-up Study population.
    JAMA The Journal of the American Medical Association 01/1998; 280(4):347-355. · 29.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: When macrometastases are delineated clearly using current radiographic techniques and/or physical examination and can be shown to concentrate 131I, the therapeutic activity to be administered may be determined quantitatively. Administrations of 131I that will deliver 30,000 rad to residual thyroid tissue or 10,000 +/- 2,000 rad to lymph node metastases will ablate them successfully 80% of the time, and bone marrow depression that is severe enough to require specialized treatment will be avoided if the whole blood dose from a single administration does not exceed 200 rad. When micrometastases are detected only by diagnostic radioiodine imaging and/or elevations of serum thyroglobulin levels, and when a clinical decision is made to treat them with radioiodine, then 131I may not be the isotope choice. With small lesions < 0.05 mm in diameter, the lower energy emissions of 125I therapy may be more suitable. With the advent of alternative methods of patient preparation for radioiodine therapy, empiric approaches that were derived from experience with endogenously hypothyroid patients will require full re-evaluation. Approaches based on quantitative radiodosimetric calculations will continue to be valid because they already consider individual differences in radioiodine kinetics.
    Thyroid 04/1997; 7(2):183-7. · 3.54 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Early diagnosis of osteomyelitis continues to be a clinical problem. Multiple imaging modalities are being used for the diagnosis of osteomyelitis, but none of them is ideal for all cases. The choice of modality depends on several factors based on an understanding of the pathophysiologic aspects of different forms of osteomyelitis. After a brief introduction outlining some basic principles regarding the diagnosis of osteomyelitis, pathophysiologic aspects are reviewed. Advantages and disadvantages of each imaging modality and their applications in different forms of osteomyelitis are discussed. The use of different imaging modalities in the diagnosis of special forms of osteomyelitis, including chronic, diabetic foot, and vertebral osteomyelitis, and osteomyelitis associated with orthopedic appliances and sickle cell disease is reviewed. Taking into account the site of suspected osteomyelitis and the presence or absence of underlying pathologic changes and their nature, an algorithm summarizing the use of various imaging modalities in the diagnosis of osteomyelitis is presented.
    European Journal of Nuclear Medicine 10/1995; 22(9):1043-63.
  • [Show abstract] [Hide abstract]
    ABSTRACT: 99mTc pentavalent dimercaptosuccinic acid [99mTc (V) DMSA], a useful agent for imaging thyroid medullary carcinoma and other tumors, can be reliably prepared by addition of NaHCO3 and then Na99mTcO4 to a commercial kit for 99mTc trivalent DMSA [99mTc (III) DMSA], followed by bubbling oxygen through the solution for 10 min. 99mTc (V) DMSA made by this method is radiochemically pure and stable for 24 h, and it gives a rat biodistribution similar to that of the agent made by previous methods. Clinical biodistribution and radiation dosimetry studies are planned.
    Nuclear Medicine and Biology 08/1995; 22(5):689-91. · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A Monte Carlo model has been developed for simulation of dose delivery to skeletal metastases by the bone surface-seeking radiopharmaceutical 186Re (Sn)-HEDP. The model simulates: (1) the heterogeneous small scale geometry of the soft tissue/bone-spicule structure in the lesions as determined by histomorphometric measurements of histologic specimens, (2) the small scale spatial distribution of the radiopharmaceutical on the lesion bone spicule surface as determined by autoradiography, and (3) the 186Re beta and conversion electron decay spectrum and the associated charged particle transport within the modeled geometries. The results are compared with the commonly employed uniform lesion model, which assumes: (1) homogeneous lesion morphology, (2) uniform distribution of radioactivity within the lesion, and (3) complete energy deposition by charged particles within the lesion due to decay of this activity. Gamma and x-ray photons from the 186Re spectrum were assumed to escape from the lesion volume in both models. Results show a significant dependence on the bone volume fraction and hence on the histology of the lesion (lytic, blastic or mixed). The uniform lesion model calculations underestimate the radiation dose to blastic lesions by as much as a factor of 1.8. However, for lytic lesions with low bone volume fractions, both models provide similar dose values. These new model calculations provide a mechanism for optimizing treatment planning and dose response evaluations of therapeutic bone-seeking radiopharmaceuticals.
    Journal of Nuclear Medicine 03/1995; 36(2):336-50. · 5.77 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Thirty-one adult patients with clinical findings suggestive of pheochromocytoma were studied with I-123 MIBG. All patients had images obtained at 24 and 48 hours. Five patients had abnormal uptake proved to be because of I-123 MIBG avid tumors. The remaining 26 patients had no proven tumors and showed physiologic uptake in various organs. The 24-hour images were of high quality. In all cases, the 48-hour images contributed no significant additional information. Only in 1 patient did the 48-hour image add some certainty. Physiologic uptake was seen in the salivary glands, liver, G.I. tract, and urinary bladder in all patients (100%). Uptake was also observed in the lung and heart (90%), normal adrenal glands (32%), thyroid (29%), spleen (23%) uterus (13%), and neck muscles (6%). The authors' experience indicates that I-123 MIBG gives superior images compared to the previously used I-131 MIBG, that the optimum imaging time for adults is 18-24 hours, and that normal distribution patterns including uterine and neck muscle uptake should be familiar to physicians interpreting the studies.
    Clinical Nuclear Medicine 03/1995; 20(2):147-52. · 2.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Trans (N,N'-ethylene bis(acetylacetoneimine)) bis(tris(3-methoxy-1-propyl) phosphine) 99mTc(III) (99mTc-Q3) has been developed for myocardial perfusion imaging. Biokinetic studies and dosimetry analysis have been completed for six healthy volunteers. The same-day two-injection protocol involved (1) an average rest injection of 241 MBq of 99mTc-Q3 followed by myocardial single-photon emission computed tomography (SPECT) at 15.0 minutes and a whole body (WB) scan at 1.5 hours; and (2) an average stress injection during treadmill exercise of 744 MBq of 99mTc-Q3 at 2.4 hours (postrest injection) followed by myocardial SPECT and additional WB scans at 1.5, 3.5, 6.5, and 21 hours poststress injection. Total urine was collected over 24 hours. Absolute organ activities were determined by conjugate counting methods. The two-injection data were simplified to a one-injection equivalent data set to facilitate dosimetry analysis. Decay corrected average percentage uptake values, plus or minus one standard deviation, for the myocardium were 1.4% +/- 0.2% at approximately 1.5 hours for both the postrest and poststress injections. The average biologic half-time for the myocardium was 26.4 hours. The highest organ uptake values included the gallbladder with 5.5% +/- 1.9% and the liver with 4.1% +/- 1.0% at the 1.5 hours poststress scan time. The sum of all gastrointestinal (GI) tract components was 18.8% +/- 9.4% at approximately 6.5 hours poststress injection (before any fecal elimination). The total 24 hour urine clearance was 17.1% +/- 2.4%. The gallbladder wall and upper large intestine wall received the highest doses at 0.024 and 0.023 mGy/MBq, respectively. The effective dose equivalent is estimated to be 0.01 mSv/MBq, which for an administration of 1110 MBq (30 mCi) is less than half that of a standard imaging protocol using 111 MBq (3 mCi) of 201Tl, and comparable to the published estimates for 99mTc-labeled sestamibi and 99mTc-labeled tetrofosmin (also normalized to 1110 MBq of administered activity). The 99mTc-Q3 exhibits myocardium uptake similar to that for these other two 99mTc agents.
    Journal of Nuclear Cardiology 01/1995; 2(5):395-404. · 2.85 Impact Factor

Publication Stats

2k Citations
486.15 Total Impact Points

Institutions

  • 2013
    • Queensland Institute of Medical Research
      Brisbane, Queensland, Australia
  • 1978–2011
    • University of Cincinnati
      • • Department of Radiology
      • • Department of Chemistry
      Cincinnati, Ohio, United States
  • 2007–2010
    • Georgetown University
      • Department of Endocrinology and Metabolism
      Washington, D. C., DC, United States
  • 2009
    • Massachusetts General Hospital
      Boston, Massachusetts, United States
  • 1998
    • University of Texas MD Anderson Cancer Center
      • Endocrine Neoplasia and Hormonal Disorders
      Houston, TX, United States
  • 1976
    • Cincinnati Eye Hospital
      Cincinnati, Ohio, United States