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Randall A Hawkins

Publications and source records attributed to Randall A Hawkins.

10 recordsLinked to original sources
PubMed2006

Evaluation of semi-quantitative scoring system for metaiodobenzylguanidine (mIBG) scans in patients with relapsed neuroblastoma.

BACKGROUND: The purpose of this study was to determine the accuracy of two semi-quantitative scoring systems to assess response to (131)I-metaiodobenzylguanidine (mIBG) therapy in recurrent neuroblastoma. PROCEDURES: Diagnostic mIBG scan pairs (n = 57) were collected for patients who underwent (131)I-mIBG therapy for relapsed neuroblastoma. Two scoring systems were designated: Method 1, which divided the body into nine segments to view osteomedullary lesions with an additional tenth segment to assess soft tissue involvement; and Method 2, which divided the body into seven segments without a corresponding compartment for soft tissue involvement. Four nuclear medicine physicians independently assigned extension and intensity scores utilizing both methods, and separately recorded their impression of whether the post-therapy scan had improved, not changed, or worsened. Inter- and intra-observer concordance and correlation with overall response and progression-free survival (PFS) were performed. RESULTS: Method 1 produced the highest inter-observer concordance and was used to calculate the relative extension scores (post-therapy score divided by pre-therapy score), which correlated significantly with overall response. Patients who achieved complete response (CR) or partial response (PR) (n = 21) had lower relative extension scores, compared to those without response (P < 0.001). The readers' overall impression associated highly (P < 0.001) with the relative extension scores though results were less quantitative. Concordance was higher if initial scores were >5. Relative extension score did not predict PFS. CONCLUSION: Semi-quantitative scoring of mIBG scans provides a more reliable method of assessing response in patients with relapsed neuroblastoma than qualitative impression. The reproducibility and high inter-observer concordance makes mIBG score an important component of overall response criteria in patients with recurrent neuroblastoma.

3-Iodobenzylguanidine↗
PubMed2006

Progress in SPECT/CT imaging of prostate cancer.

Prostate cancer is the most common type of cancer (other than skin cancer) among men in the United States. Although prostate cancer is one of the few cancers that grow so slowly that it may never threaten the lives of some patients, it can be lethal once metastasized. Indium-111 capromab pendetide (ProstaScint, Cytogen Corporation, Princeton, NJ) imaging is indicated for staging and recurrence detection of the disease, and is particularly useful to determine whether or not the disease has spread to distant metastatic sites. However, the interpretation of 111In-capromab pendetide is challenging without correlated structural information mostly because the radiopharmaceutical demonstrates nonspecific uptake in the normal vasculature, bowel, bone marrow, and the prostate gland. We developed an improved method of imaging and localizing 111In-Capromab pendetide using a SPECT/CT imaging system. The specific goals included: i) development and application of a novel iterative SPECT reconstruction algorithm that utilizes a priori information from coregistered CT; and ii) assessment of clinical impact of adding SPECT/CT for prostate cancer imaging with capromab pendetide utilizing the standard and novel reconstruction techniques. Patient imaging studies with capromab pendetide were performed from 1999 to 2004 using two different SPECT/CT scanners, a prototype SPECT/CT system and a commercial SPECT/CT system (Discovery VH, GE Healthcare, Waukesha, WI). SPECT projection data from both systems were reconstructed using an experimental iterative algorithm that compensates for both photon attenuation and collimator blurring. In addition, the data obtained from the commercial system were reconstructed with attenuation correction using an OSEM reconstruction supplied by the camera manufacturer for routine clinical interpretation. For 12 sets of patient data, SPECT images reconstructed using the experimental algorithm were interpreted separately and compared with interpretation of images obtained using the standard reconstruction technique. The experimental reconstruction algorithm improved spatial resolution, reduced streak artifacts, and yielded a better correlation with anatomic details of CT in comparison to conventional reconstruction methods (e.g., filtered back-projection or OSEM with attenuation correction only). Images produced with the experimental algorithm produced a subjective improvement in the confidence of interpretation for 11 of 12 studies. There were also changes in interpretations for 4 of 12 studies although the changes were not sufficient to alter prognosis or the patient treatment plan.

Algorithms↗
PubMed2006

Malignant pheochromocytomas and paragangliomas: a phase II study of therapy with high-dose 131I-metaiodobenzylguanidine (131I-MIBG).

Thirty patients with malignant pheochromocytoma (PHEO) or paraganglioma (PGL) were treated with high-dose 131I-MIBG. Patients were 11-62 (mean 39) years old: 19 patients males and 11 females. Nineteen patients had PGL, three of which were multifocal. Six PGLs were nonsecretory. Eleven patients had PHEO. All 30 patients had prior surgery. Fourteen patients were refractory to prior radiation or chemotherapy before 131I-MIBG. Peripheral blood stem cells (PBSCs) were collected and cryopreserved. 131I-MIBG was synthesized on-site, by exchange-labeling 131I with 127I-MIBG in a solid-phase Cu2+-catalyzed exchange reaction. 131I-MIBG was infused over 2 h via a peripheral IV. Doses ranged from 557 mCi to 1185 mCi (7.4 mCi/kg to 18.75 mCi/kg). Median dose was 833 mCi (12.55 mCi/kg). Marrow hypoplasia commenced 3 weeks after 131I-MIBG therapy. After the first 131I-MIBG therapy, 19 patients required platelet transfusions; 19 received GCSF; 12 received epoeitin or RBCs. Four patients received a PBSC infusion. High-dose 131I-MIBG resulted in the following overall tumor responses in 30 patients: 4 sustained complete remissions (CRs); 15 sustained partial remissions (PRs); 1 sustained stable disease (SD); 5 progressive disease (PD); 5 initial PRs or SD but relapsed to PD. Twenty-three of the 30 patients remain alive; deaths were from PD (5), myelodysplasia (1), and unrelated cause (1). Overall predicted survival at 5 years is 75% (Kaplan Meier estimate). For patients with metastatic PHEO or PGL, who have good *I-MIBG uptake on diagnostic scanning, high-dose 131I-MIBG therapy was effective in producing a sustained CR, PR, or SD in 67% of patients, with tolerable toxicity.

3-Iodobenzylguanidine↗
PubMed2005

Tumor response and toxicity with multiple infusions of high dose 131I-MIBG for refractory neuroblastoma.

BACKGROUND: (131)I Metaiodobenzylguanidine ((131)I-MIBG) is an effective targeted radiotherapeutic for neuroblastoma with response rates greater than 30% in refractory disease. Toxicity is mainly limited to myelosuppression. The aim of this study was to determine the response rate and hematologic toxicity of multiple infusions of (131)I-MIBG. PROCEDURE: Patients received two to four infusions of (131)I-MIBG at activity levels of 3-19 mCi/kg per infusion. Criteria for subsequent infusions were neutrophil recovery without stem cell support and lack of disease progression after the first infusion. RESULTS: Sixty-two infusions were administered to 28 patients, with 24 patients receiving two infusions, two patients receiving three infusions, and two patients receiving four infusions. All patients were heavily pre-treated, including 16 with prior myeloablative therapy. Eleven patients (39%) had overall disease response to multiple therapies, including eight patients with measurable responses to each of two or three infusions, and three with a partial response (PR) after the first infusion and stable disease after the second. The main toxicity was myelosuppression, with 78% and 82% of patients requiring platelet transfusion support after the first and second infusion, respectively, while only 50% had grade 4 neutropenia, usually transient. Thirteen patients did not recover platelet transfusion independence after their final MIBG infusion; stem cell support was given in ten patients. CONCLUSIONS: Multiple therapies with (131)I-MIBG achieved increasing responses, but hematologic toxicity, especially to platelets, was dose limiting. More effective therapy might be given using consecutive doses in rapid succession with early stem cell support.

3-Iodobenzylguanidine↗
PubMed2005

Correction of photon attenuation and collimator response for a body-contouring SPECT/CT imaging system.

UNLABELLED: (111)In-Capromab pendetide imaging is indicated for postprostatectomy patients at risk for residual or recurrent disease. However, this study is complicated by relatively long times for tumor uptake and background washout that require imaging to be performed several days after radiopharmaceutical administration. In addition, (111)In-capromab pendetide demonstrates uptake in normal structures that produce images that are interpreted best using correlation with anatomic imaging. Finally, the visual quality of radionuclide imaging can be improved with corrections for photon attenuation and for the geometric response of the radionuclide collimator. Therefore, we have evaluated the advantages of using a commercially available dual-modality SPECT/CT system. In this article, we evaluate a novel iterative reconstruction algorithm using the SPECT/CT data obtained from phantoms and (111)In-capromab pendetide patient studies. METHODS: Phantom data acquired with the dual-head SPECT camera were reconstructed using both filtered backprojection (FBP) and an iterative maximum-likelihood expectation maximization (MLEM) algorithm incorporating corrections for (a) attenuation coefficient at the effective energy of the radionuclide (either (99m)Tc or (111)In) and (b) collimator response based on experimentally measured depth-dependent spatial resolution of the camera. The collimator response model used the coregistered CT image to estimate the source-target distances produced by the patient-contouring logic of the SPECT camera. Spatial resolution was measured using SPECT images of 2 line sources and uniformity from a uniform cylindric tank. Clinical (111)In-capromab pendetide SPECT/CT data were acquired according to the radiopharmaceutical manufacturer's protocol. Region-of-interest (ROI) analysis of a transverse slice at the level of the sacral base produced mean, median, maximum, and minimum counts per pixel for bone marrow and surrounding soft-tissue ROIs. Ratios of the mean capromab pendetide uptake within marrow to uptake within soft tissue were compared for images reconstructed with FBP versus that obtained from the MLEM method with photon attenuation and collimator response corrections. RESULTS: The source-target distances reconstructed from the patient-specific CT image agreed well with the corresponding values recorded manually from the camera display unit. This information was incorporated into the iterative reconstruction algorithms and improved the quality of SPECT images from phantoms and patients versus SPECT images reconstructed without the depth-dependent collimator response model. Qualitatively, SPECT images reconstructed with corrections for photon attenuation and collimator response showed less background activity and improved target contrast compared with those images reconstructed with FBP. The target-to-background ratio (marrow uptake-to-soft-tissue uptake) was significantly better using MLEM reconstruction than with FBP when mean uptake values were measured. CONCLUSION: A priori anatomic data can be used to enhance the quality of the SPECT image when reconstructed using iterative techniques (e.g., MLEM) that use the CT data to produce a patient-specific attenuation map and a collimator response model based on the body contour produced during the SPECT acquisition.

Algorithms↗
PubMed2003

Secondary myelodysplastic syndrome and leukemia following 131I-metaiodobenzylguanidine therapy for relapsed neuroblastoma.

PURPOSE: To describe three patients with secondary leukemia after treatment with 131I-metaiodobenzylguanidine (MIBG) for neuroblastoma. METHODS: Of 95 children with refractory neuroblastoma treated with 131I-MIBG at UCSF, 3 have been identified with secondary myelodysplasia/leukemia. The case records and bone marrow results were reviewed, along with a review of the literature. RESULTS: Three patients developed secondary myelodysplasia/leukemia, at 7, 11, and 12 months following 131I-MIBG therapy. Cytogenetic abnormalities included -7q/-5, -7/+2q37, -11 and +12. Three additional cases were found in literature review of 509 reported patients treated with 131I-MIBG for neuroblastoma. CONCLUSIONS: Therapy with 131I-MIBG may contribute to the risk of secondary leukemia in patients who have received intensive chemotherapy, thought the risk of this complication is far lower than the risk of disease progression. Further monitoring for this complication is indicated.

3-Iodobenzylguanidine↗
PubMed2002

Dual-modality imaging of cancer with SPECT/CT.

Dual-modality imaging is an in vivo diagnostic technique that obtains structural and functional information directly from patient studies in a way that cannot be achieved with separate imaging systems alone. Dual-modality imaging systems are configured by combining computed tomography (CT) with radionuclide imaging (using positron emission tomography (PET) or single-photon emission computed tomography (SPECT)) on a single gantry which allows both functional and structural imaging to be performed during a single imaging session without having the patient leave the imaging system. A SPECT/CT system developed at UCSF is being used in a study to determine if dual-modality imaging offers advantages for assessment of patients with prostate cancer using (111)In-ProstaScint, a radiolabeled antibody for the prostate-specific membrane antigen. (111)In-ProstaScint images are reconstructed using an iterative maximum-likelihood expectation-maximization (ML-EM) algorithm with correction for photon attenuation using a patient-specific map of attenuation coefficients derived from CT. The ML-EM algorithm accounts for the dual-photon nature of the 111In-labeled radionuclide, and incorporates correction for the geometric response of the radionuclide collimator. The radionuclide image then can be coregistered and overlaid in color on a grayscale CT image for improved localization of the functional information from SPECT. Radionuclide images obtained with SPECT/CT and reconstructed using ML-EM with correction for photon attenuation and collimator response improve image quality in comparison to conventional radionuclide images obtained with filtered backprojection reconstruction. These results illustrate the potential advantages of dual-modality imaging for improving the quality and the localization of radionuclide uptake for staging disease, planning treatment, and monitoring therapeutic response in patients with cancer.

Algorithms↗
PubMedDate not supplied

Malignant pleural mesothelioma: evaluation with CT, MR imaging, and PET.

Imaging plays an essential role in the evaluation of malignant pleural mesothelioma (MPM). Computed tomography is the primary imaging modality used for the diagnosis and staging of MPM. Magnetic resonance (MR) imaging and, more recently, positron emission tomography (PET) have emerged as modalities that can provide additional important diagnostic and prognostic information to help further delineate the extent of disease, especially in surgical candidates. Use of MR imaging performed with different pulse sequences and gadolinium-based contrast material can improve the detection of tumor extension, especially to the chest wall and diaphragm. PET can provide both anatomic and metabolic information, especially in cases of extrathoracic and mediastinal nodal metastasis. Each imaging modality has its advantages and limitations, but their combined use is crucial in determining the most appropriate treatment options for patients with MPM.

Aged↗
PubMedDate not supplied

Design and applications of a multimodality image data warehouse framework.

A comprehensive data warehouse framework is needed, which encompasses imaging and non-imaging information in supporting disease management and research. The authors propose such a framework, describe general design principles and system architecture, and illustrate a multimodality neuroimaging data warehouse system implemented for clinical epilepsy research. The data warehouse system is built on top of a picture archiving and communication system (PACS) environment and applies an iterative object-oriented analysis and design (OOAD) approach and recognized data interface and design standards. The implementation is based on a Java CORBA (Common Object Request Broker Architecture) and Web-based architecture that separates the graphical user interface presentation, data warehouse business services, data staging area, and backend source systems into distinct software layers. To illustrate the practicality of the data warehouse system, the authors describe two distinct biomedical applications--namely, clinical diagnostic workup of multimodality neuroimaging cases and research data analysis and decision threshold on seizure foci lateralization. The image data warehouse framework can be modified and generalized for new application domains.

Decision Making, Computer-Assisted↗