Publications (58) View all
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Article: Challenges in accurate registration of 3-D medical imaging and histopathology in primary prostate cancer.
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ABSTRACT: Due to poor correlation between slice thickness and orientation, verification of medical imaging results by histology is difficult. Often validation of imaging findings of lesions suspicious for prostate cancer is driven by a subjective, visual approach to correlate in vivo images with histopathology. We describe fallacious assumptions in the correlation of imaging findings with pathology and identify the lack of accurate registration as a major obstacle in the validation of PET and PET/CT imaging in primary prostate cancer. Specific registration techniques that facilitate the most difficult part of the registration process-the mapping of pathology onto high-resolution imaging, preferably aided by the ex vivo prostate specimen-are discussed.European Journal of Nuclear Medicine 03/2013; · 4.53 Impact Factor -
Article: Dynamic Bone Imaging with 99mTc-Labeled Diphosphonates and 18F-NaF: Mechanisms and Applications.
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ABSTRACT: Dynamic bone scanning with 99mTc-labeled diphosphonates and 18F-labeled sodium fluoride provides functional information sensitive for subtle changes in bone turnover and perfusion, which assists the clinical management of numerous osseous pathologies. This article reviews the mechanisms of uptake of 99mTc-labeled diphosphonates and 18F-sodium fluoride and discusses and compares the performance of these bone-seeking radiotracers for clinical and research applications, using dynamic and multiple-time-point imaging protocols and quantitative techniques.Journal of Nuclear Medicine 03/2013; · 6.38 Impact Factor -
Article: Introducing parametric fusion PET/MRI of primary prostate cancer.
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ABSTRACT: We assessed the performance of parametric fusion PET/MRI based on (11)C-choline PET/CT and apparent diffusion coefficient (ADC) maps derived from diffusion-weighted MRI for the identification of primary prostate cancer. (11)C-choline PET/CT and MRI were performed in 17 patients with untreated primary prostate cancer, followed by prostatectomy. Registration of in vivo imaging with histology was achieved using a mutual-information objective function and by performing ex vivo MRI of the prostatectomy specimen (obtained at 3 T) and whole-mount sectioning with block-face photography as intermediate steps. Data analysis included volumetrically registered whole-mount histology with Gleason scoring, (11)C-choline, and ADC data (obtained at 1.5 T). Volumes of interest were defined on the basis of histologically proven tumor tissue to calculate tumor-to-benign prostate background ratios (TBRs) for (11)C-choline, ADC, and a derived fusion PET/MRI parameter calculating the quotient of (11)C-choline over ADC (P(CHOL/ADC)). Fifty-one tumor nodules were identified at pathology. The TBRs for (11)C-choline (P < 0.05) and P(CHOL/ADC) (P < 0.005) were significantly higher in prostate cancers with a Gleason score of ≥3 + 4 than with a Gleason score of ≤3 + 3 disease and controls. For Gleason ≥ 3 + 4, the ADC TBRs were significantly lower than controls and Gleason ≤ 3 + 3 disease (P < 0.05). The absolute value of TBRs obtained from Gleason ≥ 3 + 4 cancers increased from ADC to (11)C-choline PET/CT and from (11)C-choline PET/CT to P(CHOL/ADC), with each step being statistically significant. Our data indicate that parametric PET/MRI using P(CHOL/ADC) improves lesion-to-background contrast (TBRs) of Gleason ≥ 3 + 4 disease, compared with (11)C-choline PET/CT or diffusion-weighted MRI, and thus hold promise that parametric imaging performed on hybrid PET/MRI may further improve identification and localization of significant primary prostate cancer.Journal of Nuclear Medicine 03/2012; 53(4):546-51. · 6.38 Impact Factor -
Article: Investigation on tumor hypoxia in resectable primary prostate cancer as demonstrated by 18F-FAZA PET/CT utilizing multimodality fusion techniques.
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ABSTRACT: As hypoxia is believed to play an important role in the development and progression of prostate cancer, we evaluated whether 18F-labeled fluoroazomycin arabinoside (18F-FAZA) would be useful to identify tumor hypoxia in resectable prostate cancer. Positron emission tomography (PET)/CT was performed on 14 patients with untreated localized primary prostate cancer 3 h post-injection of approximately 390 MBq of 18F-FAZA using forced diuresis to decrease radioactivity in the urinary bladder. Anatomical trans-pelvic coil and pre- and post-contrast 1.5 T MRI with endorectal coil were performed on the same day. Patients underwent radical prostatectomy and ex vivo 3 T MRI of the prostatectomy specimen within 14 days following in vivo imaging. Imaging results were verified by whole mount histopathology plus tissue microarray (TMA) immunohistochemical (IHC) analysis for carbonic anhydrase IX (CAIX) and hypoxia-inducible factor 1α (HIF-1α). Registration of in vivo imaging with histology was achieved using mutual information software and performing ex vivo MRI of the prostatectomy specimen and whole mount sectioning with block face photography as intermediate steps. Whole mount histology identified 43 tumor nodules, 19 of them larger than 1 ml as determined on coregistered volumes featuring 18F-FAZA, MRI, and histological 3-D image information. None of these lesions was found to be positive for CAIX or visualized by 18F-FAZA PET/CT while IHC for HIF-1α showed variable staining of tumor tissues. Accordingly, no correlation was found between 18F-FAZA uptake and Gleason scores. Our data based on 18F-FAZA PET/CT and CAIX IHC do not support the presence of clinically relevant hypoxia in localized primary prostate cancer including high-grade disease. Activation of HIF-1α may be independent of tissue hypoxia in primary prostate cancer.European Journal of Nuclear Medicine 07/2011; 38(10):1816-23. · 4.53 Impact Factor -
Article: Benefits of hybrid SPECT/CT for (111)In-oxine- and Tc-99m-hexamethylpropylene amine oxime-labeled leukocyte imaging.
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ABSTRACT: This retrospective study assessed the effect of the addition of SPECT/CT imaging on the diagnostic accuracy of labeled leukocyte scintigraphy. Leukocyte scans of 134 patients performed between December 2005 and December 2009 were reviewed. All patients underwent whole-body planar and SPECT/CT imaging with either (111)In-oxine- or Tc-99m-hexamethylpropylene amine oxime (HMPAO)-labeled leukocytes. Leukocyte imaging identified a total of 221 lesions. Based on additional diagnostic tests and clinical follow-up, a final diagnosis was established in 115 patients. A total of 113 focal lesions with an established final diagnosis were detected on imaging in bone (n = 43), soft-tissues (n = 34), vascular grafts (n = 19), and other surgical implants (n = 17), whereas 26 scans resulted negative. Overall, leukocyte scanning including SPECT/CT yielded sensitivity, specificity, positive and negative predictive values of 87.5%, 85.3%, 83.6%, and 88.9%, respectively. As compared to planar imaging and SPECT, SPECT/CT imaging significantly increased the number of correctly identified lesion locations and improved overall reader confidence in 77 (68%) and 71 (63%) of 113 focal lesions, respectively (P < 0.001). Significant differences in scan accuracy were neither observed between In-oxine- or Tc-99m-hexamethylpropylene amine oxime-labeled leukocyte studies, nor between scans obtained with or without antibiotic treatment. Hybrid SPECT/CT leukocyte imaging has incremental value over planar imaging with SPECT because of improved diagnostic accuracy of lesion identification and reader confidence.Clinical nuclear medicine 07/2011; 36(7):e50-6. · 3.92 Impact Factor
