Perry W Grigsby

Washington University in St. Louis, San Luis, Missouri, United States

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Publications (373)1469.62 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate outpatient-based high-dose-rate (HDR) interstitial brachytherapy (ISBT) in the treatment of gynecologic malignancies. Between December 2006 and July 2012, 50 patients were treated with twice-daily outpatient-based HDR iridium-192 ISBT at our institution. Thirty-two patients had vaginal cancers, 13 vulvar, 3 urethral, and 2 cervical cancers. The most common histologies were squamous cell carcinoma (58%) and endometrioid adenocarcinoma (26%). Twenty-six patients were treated with definitive radiation therapy with or without platinum-based chemotherapy, 16 were treated for recurrent disease, 5 were treated in the postoperative setting, and 3 were treated palliatively. Forty patients received external beam radiation therapy before ISBT. Median followup was 13.7 months. Median interstitial dose was 18 Gy in 2.25 Gy twice-daily fractions prescribed to the implant volume. Median external beam dose was 50.4 Gy in 1.8 Gy daily fractions prescribed to the primary disease site. Eight patients (16%) were seen in the emergency room or were admitted to the hospital during treatment. Six patients (17%) experienced significant complications after treatment (3 ulcerations at the primary site, 1 vaginal necrosis, 1 vaginal abscess, and 1 patient with urinary obstruction). Larger volume encompassing 100% of the prescribed dose was correlated with significant complications on multivariate analysis (p = 0.039). Actuarial local control at 1 year was 72%, with univariate analysis demonstrating worse local control for nonendometrioid adenocarcinoma compared with squamous cell carcinoma (20% vs. 84%, p = 0.044). Outpatient-based HDR ISBT is feasible and safe, with toxicity and local control rates consistent with historical outcomes. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
    Brachytherapy 04/2015; 14(2). DOI:10.1016/j.brachy.2014.11.017 · 1.99 Impact Factor
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    ABSTRACT: To evaluate recurrence patterns and overall survival in patients treated with adjuvant radiation after surgical staging for Stage II endometrial carcinoma. Secondary goals include identification of prognostic factors for recurrence and toxicity assessment. The medical records of 41 patients treated with adjuvant radiotherapy at Washington University School of Medicine after surgical staging for endometrial cancer (total abdominal hysterectomy and bilateral salpingo-oophorectomy, peritoneal cytology, lymph node dissection) were reviewed. Nineteen were treated with a combination of external beam radiotherapy and vaginal brachytherapy (VB), and 22 patients were treated with postoperative VB alone. Median followup for all patients was 41 months. Median patient age was 59 years (range, 42-87 years). All tumors were of endometrioid histology. There were 20 Grade 1 tumors, 13 Grade 2 tumors, and 8 Grade 3 tumors. For all patients, the 5-year overall survival was 69.8%, and the 5-year recurrence-free survival was 89.0%. There was no statistically significant difference in overall survival (p = 0.510) or freedom from vaginal (p = 0.840), distant (p = 0.133), or any recurrence (p = 0.275) with respect to modality of treatment (external beam radiotherapy and VB vs. VB alone). There were no pelvic lymph node recurrences. In the univariate analysis, there were no risk factors influencing overall survival or recurrences. One patient experienced a toxicity requiring hospital admission. She was treated with pelvic external beam radiation plus brachytherapy. VB alone results in excellent local control for patients with Stage II endometrial cancer after surgical staging. Long-term toxicities are rare and more common in the group of patients who were treated with pelvic external beam plus brachytherapy. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
    Brachytherapy 04/2015; DOI:10.1016/j.brachy.2015.02.196 · 1.99 Impact Factor
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    ABSTRACT: The purpose of this pictorial review is to describe emerging clinical applications of positron emission tomography (PET)/magnetic resonance imaging (MRI), the newest clinical hybrid imaging modality, with a specific focus on abdominal and pelvic malignancies. Important issues regarding the clinical implementation of PET/MRI systems, including workflow considerations and protocol development, are examined. The unique technical challenges of simultaneous PET/MRI acquisition and MRI-based attenuation correction are also briefly discussed. This article is intended to provide the body imager with an overview of the potential diagnostic advantages of PET/MRI, as compared to PET/CT or MRI alone.
    Abdominal Imaging 03/2015; DOI:10.1007/s00261-015-0390-3 · 1.73 Impact Factor
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    Frank J Brooks, Perry W Grigsby
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    ABSTRACT: There is increasing interest in applying image texture quantifiers to assess the intra-tumor heterogeneity observed in FDG-PET images of various cancers. Use of these quantifiers as prognostic indicators of disease outcome and/or treatment response has yielded inconsistent results. We study the general applicability of some well-established texture quantifiers to the image data unique to FDG-PET. We first created computer-simulated test images with statistical properties consistent with clinical image data for cancers of the uterine cervix. We specifically isolated second-order statistical effects from low-order effects and analyzed the resulting variation in common texture quantifiers in response to contrived image variations. We then analyzed the quantifiers computed for FIGOIIb cervical cancers via receiver operating characteristic (ROC) curves and via contingency table analysis of detrended quantifier values. We found that image texture quantifiers depend strongly on low-effects such as tumor volume and SUV distribution. When low-order effects are controlled, the image texture quantifiers tested were not able to discern only the second-order effects. Furthermore, the results of clinical tumor heterogeneity studies might be tunable via choice of patient population analyzed. Some image texture quantifiers are strongly affected by factors distinct from the second-order effects researchers ostensibly seek to assess via those quantifiers.
    PLoS ONE 02/2015; 10(2):e0116574. DOI:10.1371/journal.pone.0116574 · 3.53 Impact Factor
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    ABSTRACT: The BRAF mutation occurs commonly in papillary thyroid carcinoma (PTC). Previous investigations of its utility to predict recurrence-free survival (RFS) and disease-specific survival (DSS) have reported conflicting results and its role remains unclear. The purpose of this retrospective study was to determine the incidence of the BRAF mutation and analyze its relationship to clinicopathologic risk factors and long-term outcomes in the largest, single-institution American cohort to date. BRAF mutational status was determined in 508 PTC patients using RFLP analysis. The relationships between BRAF mutation status, patient and tumor characteristics, RFS, and DSS were analyzed. The BRAF mutation was present in 67% of patients. On multivariate analysis, presence of the mutation predicted only for capsular invasion (HR, 1.7; 95% CI, 1.1-2.6), cervical lymph node involvement (HR, 1.7; 95% CI, 1.1-2.7), and classic papillary histology (HR, 1.8; 95% CI 1.1-2.9). There was no significant relationship between the BRAF mutation and RFS or DSS, an observation that was consistent across univariate, multivariate, and Kaplan-Meier analyses. This is the most extensive study to date in the United States to demonstrate that BRAF mutation is of no predictive value for recurrence or survival in PTC. We found correlations of BRAF status and several clinicopathologic characteristics of high-risk disease, but limited evidence that the mutation correlates with more extensive or aggressive disease. This analysis suggests that BRAF is minimally prognostic in PTC. However, prevalence of the BRAF mutation is 70% in the general population, providing the opportunity for targeted therapy. © 2015 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.
    Cancer Medicine 02/2015; DOI:10.1002/cam4.417
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    ABSTRACT: In this review, we review the literature on the use of PET in radiation treatment planning, with an emphasis on describing our institutional methodology (where applicable). This discussion is intended to provide other radiation oncologists with methodological details on the use of PET imaging for treatment planning in radiation oncology, or other oncologists with an introduction to the use of PET in planning radiation therapy. Copyright © 2015 Elsevier Inc. All rights reserved.
    PET Clinics 11/2014; DOI:10.1016/j.cpet.2014.09.003
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    ABSTRACT: Cervical cancer is the third most common cancer in women worldwide, leading to about 300,000 deaths each year. Most cervical cancers are caused by human papillomavirus (HPV) infection. However, persistent transcriptional activity of HPV oncogenes, which indicates active roles of HPV in cervical cancer maintenance and progression, has not been well characterized. Using our recently developed assays for comprehensive profiling of HPV E6/E7 transcripts, we have detected transcriptional activities of 10 high-risk HPV strains from 87 of the 101 cervical tumors included in the analysis. These HPV-positive patients had significantly better survival outcome compared with HPV-negative patients, indicating HPV transcriptional activity as a favorable prognostic marker for cervical cancer. Furthermore, we have determined microRNA (miRNA) expression changes that were correlated with tumor HPV status. Our profiling and functional analyses identified miR-9 as the most activated miRNA by HPV E6 in a p53-independent manner. Further target validation and functional studies showed that HPV-induced miR-9 activation led to significantly increased cell motility by downregulating multiple gene targets involved in cell migration. Thus, our work helps to understand the molecular mechanisms as well as identify potential therapeutic targets for cervical cancer and other HPV-induced cancers.
    Oncotarget 10/2014; 5(22). · 6.63 Impact Factor
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    ABSTRACT: Purpose Magnetic resonance imaging/diffusion weighted-imaging (MRI/DWI)-guided high-dose-rate (HDR) brachytherapy and 18F-fluorodeoxyglucose (FDG) — positron emission tomography/computed tomography (PET/CT)-guided intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer is a novel treatment technique. The purpose of this study was to report our analysis of dose-volume parameters predicting gross tumor volume (GTV) control. Methods and Materials We analyzed the records of 134 patients with International Federation of Gynecology and Obstetrics stages IB1-IVB cervical cancer treated with combined MRI-guided HDR and IMRT from July 2009 to July 2011. IMRT was targeted to the metabolic tumor volume and lymph nodes by use of FDG-PET/CT simulation. The GTV for each HDR fraction was delineated by use of T2-weighted or apparent diffusion coefficient maps from diffusion-weighted sequences. The D100, D90, and Dmean delivered to the GTV from HDR and IMRT were summed to EQD2. Results One hundred twenty-five patients received all irradiation treatment as planned, and 9 did not complete treatment. All 134 patients are included in this analysis. Treatment failure in the cervix occurred in 24 patients (18.0%). Patients with cervix failures had a lower D100, D90, and Dmean than those who did not experience failure in the cervix. The respective doses to the GTV were 41, 58, and 136 Gy for failures compared with 67, 99, and 236 Gy for those who did not experience failure (P<.001). Probit analysis estimated the minimum D100, D90, and Dmean doses required for ≥90% local control to be 69, 98, and 260 Gy (P<.001). Conclusions Total dose delivered to the GTV from combined MRI-guided HDR and PET/CT-guided IMRT is highly correlated with local tumor control. The findings can be directly applied in the clinic for dose adaptation to maximize local control.
    International journal of radiation oncology, biology, physics 09/2014; 90(4). DOI:10.1016/j.ijrobp.2014.07.039 · 4.18 Impact Factor
  • American Society for Therapeutic Radiology and Oncology's 56ths Annual Meeting (ASTRO), San Francisco, CA; 09/2014
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    ABSTRACT: Purpose: The objective of this study was to report the results of in vitro chemoresponse analysis of primary, metastatic, and recurrent human cervical cancers. Methods: There were 557 tumor specimens submitted for testing from August 2006 to June 2010. Single agents tested were cisplatin, carboplatin, paclitaxel, docetaxel, epirubicin, fluorouracil, 4-hydroxy ifosfamide (activemetabolite of ifosfamide), SN-38 (activemetabolite of irinotecan), topotecan, and vinorelbine. Doublets tested were carboplatin/paclitaxel and cisplatin/topotecan. Tumor responsewas determined fromdose-response curves. Results were scored as responsive, intermediate, or nonresponsive. Chemoresponse was reported as the combined responsive and intermediate results. Results: Three hundred fifty-three (63.4%) of 557 submitted specimens were successfully assayed. Confirmation of histology and tumor status (primary, metastatic, or recurrent) was available for 273 specimens. The chemoresponse of the most active agents in primary cancers (n = 151) was 75% for SN-38, 71% for 4-hydroxy ifosfamide, 62% for topotecan, and 73% for carboplatin/paclitaxel. The chemoresponse of metastatic cancers (n = 66) was 54% for SN-38, 51% for 4-hydroxy ifosfamide, 44% for epirubicin, and 53% for carboplatin/paclitaxel. The chemoresponse for recurrent cancers (n = 56) was 44% for epirubicin, 41% for 4-hydroxy ifosfamide, 39% for vinorelbine, 39% for paclitaxel, 36% for topotecan, 46% for carboplatin/paclitaxel, and 35% for cisplatin/topotecan. The overall chemoresponse was greater in primary cancers (58%) than in recurrent cancers (35%) (P < 0.0001). Conclusions: In vitro chemoresponse analysis of cervical cancer biospecimens is feasible. Chemoresponse results are variable depending on tumor status. Clinical studies of assay-directed therapy should be developed.
    International Journal of Gynecological Cancer 07/2014; 24(9). DOI:10.1097/IGC.0000000000000186 · 1.95 Impact Factor
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    ABSTRACT: Background Clinical outcome of papillary thyroid carcinoma (PTC) in children differs significantly from that of adults. There is no clear explanation of this difference although previous studies have demonstrated a lower prevalence of the BRAFV600E mutation in PTC of children. However, data are limited due to the rarity of this diagnosis. BRAFV600E mutation prevalence and its relationship with outcome in pediatric PTC remain unclear.ProcedureBRAFV600E mutational status was determined in 27 PTC patients less than 22 years of age using restriction fragment length polymorphism (RFLP) analysis. The relationship between BRAFV600E mutation status, patient and tumor characteristics as well as progression-free survival (PFS) were analyzed.ResultsBRAFV600E was present in 63% of patients and occurred more often in male patients versus females (P = 0.033). Presence of the mutation did not correlate with any difference in extent of disease at diagnosis, tumor size, capsular invasion, vascular invasion, soft tissue invasion, or margin status. At 10 years, PFS for BRAFV600E positive versus negative patients was 55.5% versus 70.0%, respectively (P = 0.48). Overall survival was 100% and median follow-up was 13.9 years.Conclusions This study of pediatric PTC demonstrates that BRAFV600E mutations occur in children at a rate comparable to adults. We found a correlation of BRAFV600E with the male gender, but no evidence that the mutation correlates with more extensive or aggressive disease. This analysis suggests that differences in disease course of PTC in children versus adults are not strongly dependent upon the presence of the BRAFV600E mutation. Pediatr Blood Cancer © 2014 Wiley Periodicals, Inc.
    Pediatric Blood & Cancer 07/2014; DOI:10.1002/pbc.24935 · 2.56 Impact Factor
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    ABSTRACT: Combination chemotherapy and radiation are used for adjuvant treatment of stage III-IV endometrial cancer. The goal of this study was to review the treatment duration, toxicity, and survival for patients treated with concomitant chemotherapy and radiation. Women with stage III-IV endometrial cancer treated with concurrent chemotherapy and radiation between 2006 and 2013 were included. Toxicities were classified per CTCAE v3.0 and RTOG/EORTC late radiation morbidity scoring. Descriptive statistics were used to quantify treatment and toxicities. Kaplan-Meier method was used to estimate survival. Fifty-one patients met our inclusion criteria. Median age was 60 (range 33-85). Thirty-six patients (70.6%) had endometrioid histology, 13 patients (25.5%) had serous, clear cell, or mixed histology, and two women (3.9%) had carcinosarcoma. Forty-eight patients had stage III disease and three patients were stage IVB. Mean treatment duration was 107±19days. Forty-two patients received all planned chemotherapy, and sixteen patients required a dose reduction. Thirty-four patients (66.7%) experienced grade 3-4 toxicities, the majority of which were hematologic. There were no deaths related to therapy. Eighty-six percent of patients received leukocyte growth factors, and 25% of patients received a blood transfusion. Seven late grade 3-4 complications occured: four gastrointestinal, two genitourinary, and one patient had ongoing neuropathy. Median progression-free survival was 42.8months (range 4.4-81.5months) and median overall survival was 44.9months (range 5.1-82.6months). Three-year overall survival was 80%. Concomitant chemotherapy and radiation is an adequately tolerated treatment modality that allows for shorter treatment duration.
    Gynecologic Oncology 05/2014; 134(1). DOI:10.1016/j.ygyno.2014.05.002 · 3.69 Impact Factor
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    ABSTRACT: Background: Well-differentiated thyroid carcinoma (DTC) in children and adolescents is a rare disease with favorable prognosis despite regional and distant metastasis at presentation in many patients. Treatment recommendations are varied and there is little consensus on follow-up guidelines for these patients. Methods: Medical records of patients less than 22 years of age treated at our institution were reviewed. 112 patients treated between 1969 and 2009 were selected for further analysis. Effects of patient and tumor characteristics on progression-free survival were evaluated along with the predictive value of whole-body 131I scintigraphy in the follow-up setting. Results: Overall survival at 20 years and 30 years was 100% and 94.4%, respectively. Progression-free survival (PFS) at 10, 20 and 30 years was 71%, 62% and 55%, respectively. Although male patients and younger patients presented with more advanced disease, gender and age at diagnosis had no effect on risk of PFS. Additionally, neither the presence of vascular invasion, capsular extension, positive margins nor soft-tissue invasion had an effect on PFS. Mean time to recurrence in patients who underwent immediate postoperative 131I therapy was 3.8 years compared to 14.1 years in patients who either never received 131I therapy or were treated in the salvage setting (p<0.0001). Negative posttreatment whole-body 131I scintigraphy was strongly predictive for decreased risk of recurrence, especially in patients with three consecutive negative scans. Conclusions: Pediatric patients are more likely to present with advanced disease and for this reason, the majority of patients treated at our institution receive postoperative radioactive iodine. Long term surveillance is required in this population because of the risk of late recurrences. Whole-body 131I scintigraphy is useful for risk stratification; after three consecutive negative scans the risk of recurrence is low.
    Thyroid: official journal of the American Thyroid Association 04/2014; 24(7). DOI:10.1089/thy.2013.0297 · 3.84 Impact Factor
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    ABSTRACT: PI3K/AKT pathway alterations are associated with incomplete response to chemoradiation in human cervical cancer. This study was performed to test for mutations in the PI3K pathway and to evaluate the effects of AKT inhibitors on glucose uptake and cell viability. Mutational analysis of DNA from 140 pretreatment tumor biopsies and 8 human cervical cancer cell lines was performed. C33A cells (PIK3CAR88Q and PTENR233*) were treated with increasing concentrations of two allosteric AKT inhibitors (SC-66 and MK-2206) with or without the glucose analogue 2-deoxyglucose (2-DG). Cell viability and activation status of the AKT/mTOR pathway were determined in response to the treatment. Glucose uptake was evaluated by incubation with 18F-fluorodeoxyglucose (FDG). Cell migration was assessed by scratch assay. Activating PIK3CA (E545K, E542K) and inactivating PTEN (R233*) mutations were identified in human cervical cancer. SC-66 effectively inhibited AKT, mTOR and mTOR substrates in C33A cells. SC-66 inhibited glucose uptake via reduced delivery of Glut1 and Glut4 to the cell membrane. SC-66 (1 µg/ml-56%) and MK-2206 (30 µM-49%) treatment decreased cell viability through a non-apoptotic mechanism. Decreases in cell viability were enhanced when AKT inhibitors were combined with 2-DG. The scratch assay showed a substantial reduction in cell migration upon SC-66 treatment. The mutational spectrum of the PI3K/AKT pathway in cervical cancer is complex. AKT inhibitors effectively block mTORC1/2, decrease glucose uptake, glycolysis, and decrease cell viability in vitro. These results suggest that AKT inhibitors may improve response to chemoradiation in cervical cancer.
    PLoS ONE 04/2014; 9(4):e92948. DOI:10.1371/journal.pone.0092948 · 3.53 Impact Factor
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    ABSTRACT: To assess the impact on local tumor control of intraoperative ultrasonographic plaque visualization and selective application of transpupillary thermotherapy (TTT) in the treatment of posterior uveal melanoma with iodine-125 (I-125) episcleral plaque brachytherapy (EPB). Retrospective analysis of 526 patients treated with I-125 EPB for posterior uveal melanoma. Clinical features, dosimetric parameters, TTT treatments, and local tumor control outcomes were recorded. Statistical analysis was performed using Cox proportional hazards and Kaplan-Meier life table method. The study included 270 men (51%) and 256 women (49%), with a median age of 63 years (mean, 62 years; range, 16-91 years). Median dose to the tumor apex was 94.4 Gy (mean, 97.8; range, 43.9-183.9) and to the tumor base was 257.9 Gy (mean, 275.6; range, 124.2-729.8). Plaque tilt >1 mm away from the sclera at plaque removal was detected in 142 cases (27%). Supplemental TTT was performed in 72 patients (13.7%). One or 2 TTT sessions were required in 71 TTT cases (98.6%). After a median follow-up of 45.9 months (mean, 53.4 months; range, 6-175 months), local tumor recurrence was detected in 19 patients (3.6%). Local tumor recurrence was associated with lower dose to the tumor base (P=.02). Ultrasound-guided plaque localization of I-125 EPB is associated with excellent local tumor control. Detection of plaque tilt by ultrasonography at plaque removal allows supplemental TTT to be used in patients at potentially higher risk for local recurrence while sparing the majority of patients who are at low risk. Most patients require only 1 or 2 TTT sessions.
    International journal of radiation oncology, biology, physics 01/2014; 88(4). DOI:10.1016/j.ijrobp.2013.12.014 · 4.18 Impact Factor
  • International journal of radiation oncology, biology, physics 01/2014; 88(3). DOI:10.1016/j.ijrobp.2013.11.011 · 4.18 Impact Factor
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    Frank J Brooks, Perry W Grigsby
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    ABSTRACT: Translational relevance: Many types of cancer are located and assessed via positron emission tomography (PET) using the 18F-fluorodeoxyglucose (FDG) radiotracer of glucose uptake. There is rapidly increasing interest in exploiting the intra-tumor heterogeneity observed in these FDG-PET images as an indicator of disease outcome. If this image heterogeneity is of genuine prognostic value, then it either correlates to known prognostic factors, such as tumor stage, or it indicates some as yet unknown tumor quality. Therefore, the first step in demonstrating the clinical usefulness of image heterogeneity is to explore the dependence of image heterogeneity metrics upon established prognostic indicators and other clinically interesting factors. If it is shown that image heterogeneity is merely a surrogate for other important tumor properties or variations in patient populations, then the theoretical value of quantified biological heterogeneity may not yet translate into the clinic given current imaging technology.Purpose: We explore the relation between pelvic lymph node status at diagnosis and the visually evident uptake heterogeneity often observed in 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) images of cervical carcinomas.Experimental design: We retrospectively studied the FDG-PET images of 47 node negative and 38 node positive patients, each having FIGO stage IIb tumors with squamous cell histology. Imaged tumors were segmented using 40% of the maximum tumor uptake as the tumor-defining threshold and then converted into sets of three-dimensional coordinates. We employed the sphericity, extent, Shannon entropy (S) and the accrued deviation from smoothest gradients (zeta) as image heterogeneity metrics. We analyze these metrics within tumor volume strata via: the Kolmogorov-Smirnov test, principal component analysis and contingency tables. We found no statistically significant difference between the positive and negative lymph node groups for any one metric or plausible combinations thereof. Additionally, we observed that S is strongly dependent upon tumor volume and that zeta moderately correlates with mean FDG uptake. FDG uptake heterogeneity did not indicate patients with differing prognoses. Apparent heterogeneity differences between clinical groups may be an artifact arising from either the dependence of some image metrics upon other factors such as tumor volume or upon the underlying variations in the patient populations compared.
    Radiation Oncology 12/2013; 8(1):294. DOI:10.1186/1748-717X-8-294 · 2.36 Impact Factor
  • Farrokh Dehdashti, Perry W. Grigsby, Barry A. Siegel
    Molecular Imaging & Biology 12/2013; 15(6). DOI:10.1007/s11307-013-0663-6 · 2.87 Impact Factor
  • Frank J Brooks, Perry W Grigsby
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    ABSTRACT: The number of studies in the literature involving quantification of the metabolic heterogeneity seen in (18)F-FDG PET images has increased sharply over recent years. We hypothesized that inclusion of very small regions of interest as unique data points will have deleterious effects on these studies. Using a combination of probability theory and clinical (18)F-FDG PET data, we numerically calculated the curve describing the probability a given tumor volume is large enough to adequately sample the underlying tumor biology assayed via a PET/CT scanner at a planar resolution of 4 mm and transaxial resolution of 4 mm (64 mm(3) voxel size). We then used a computer simulation to isolate the effects of tumor volume on the image local entropy. We computed the underlying global intensity distribution for 70 cervical cancer tumors ranging from 4 to 248 cm(3)), which were ensemble-averaged over the same intensity scale. From this distribution, we determined that about 700 total voxels (45 cm(3)) are required to give 95% certainty that the global intensity distribution has been sufficiently sampled for common statistical comparisons of individual tumor intensity distributions to be made canonically. We demonstrated that one previously suggested measure of heterogeneity is dependent on tumor volume and that measurement of heterogeneity is about 5 times more sensitive to volume changes for volumes below the proposed minimum than for those above it. Inclusion of tumor volumes below 45 cm(3) can profoundly bias comparisons of intratumoral uptake heterogeneity metrics derived from data from the current generation of whole-body (18)F-FDG PET scanners.
    Journal of Nuclear Medicine 11/2013; 55(1). DOI:10.2967/jnumed.112.116715 · 5.56 Impact Factor
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    ABSTRACT: Purpose: Conventional treatment planning for episcleral plaque brachytherapy entails creating a two‐dimensional (2D) isodose plan based on the tumor dimensions and distances to critical structures as defined by ultrasound and fundus photography. The purpose of this study was to compare 2D‐based metrics of the tumor and normal eye anatomy with magnetic resonance (MR)‐based metrics. Methods: Thirty‐five patients with ocular melanoma were prescribed to receive 85 Gy over 96 hours using episcleral plaque brachytherapy with iodine‐125. The plaque size and seed source strength were determined from the tumor characteristics as defined by ultrasound and fundus photography. The patients were imaged on a 1.5‐Tesla MR unit using T1‐and T2‐weighted techniques. Images were exported to a brachytherapy planning system for contouring of tumor and normal eye anatomy, and identifying points of interest for critical structures, e.g., fovea and optic disk. The tumor apex height, basal dimensions, distances between tumor edge to fovea and to optic disk were averaged over all patients, and compared between 2D‐and MR‐based methods using statistical Signed test analysis. Results: There were no statistically significant differences between 2D‐and MR‐based methods for mean tumor apex height, basal dimensions, and distance to optic disk and to fovea. Four patients presented with tumors located anteriorly in the ciliary body. This tumor location proved to be challenging in estimating distances to optic disk and fovea based on 2D methods. These distances were measurable on MR regardless of tumor location. Conclusion: We have shown that tumor dimensions and distances measured using 2D‐based methods can be reproducibly defined on MR. Future work will evaluate isodose plans on the MR images and compare them to 2D‐based isodose plans. Additional work will include investigating different MR imaging techniques to enhance soft‐tissue visualization.
    Medical Physics 06/2013; 40(6):506. DOI:10.1118/1.4815648 · 3.01 Impact Factor

Publication Stats

10k Citations
1,469.62 Total Impact Points

Institutions

  • 1987–2015
    • Washington University in St. Louis
      • Department of Radiation Oncology
      San Luis, Missouri, United States
  • 2014
    • Washington & Lee University
      Лексингтон, Virginia, United States
  • 2007
    • Temple University
      • Department of Obstetrics, Gynecology and Reproductive Sciences
      Filadelfia, Pennsylvania, United States
  • 1991–2006
    • Barnes Jewish Hospital
      • Department of Obstetrics and Gynecology
      San Luis, Missouri, United States
  • 2005
    • St. Luke's Hospital (MO, USA)
      Saint Louis, Michigan, United States
  • 2002
    • University of Utah
      Salt Lake City, Utah, United States
    • University of Pittsburgh
      Pittsburgh, Pennsylvania, United States
  • 1999
    • University of Texas MD Anderson Cancer Center
      • Department of Gynecologic Oncology
      Houston, TX, United States
  • 1998
    • University of Alabama at Birmingham
      Birmingham, Alabama, United States
  • 1995
    • Fox Chase Cancer Center
      Filadelfia, Pennsylvania, United States
  • 1989
    • Rambam Medical Center
      H̱efa, Haifa, Israel