Hossein Jadvar

Prostate Cancer: PET with 18F-FDG, 18F- or 11C-Acetate, and 18F- or 11C-Choline

Prostate cancer is biologically and clinically a heterogeneous disease that makes imaging evaluation challenging. The role of imaging in prostate cancer should include diagnosis, localization, and characterization (indolent vs. lethal) of the primary tumor, determination of extracapsular spread, guidance and evaluation of local therapy in organ-confined disease, staging of locoregional lymph nodes, detection of locally recurrent and metastatic disease in biochemical relapse, planning of radiation treatment, prediction and assessment of tumor response to salvage and systemic therapy, monitoring of active surveillance and definition of a trigger for definitive therapy, and prognostication of time to hormone refractoriness in castrate disease and overall survival. To address these tasks effectively, imaging needs to be tailored to the specific phases of the disease in a patient-specific, risk-adjusted manner. In this article, I review the preclinical and clinical evidence on the potential and emerging role of PET with the 3 most commonly studied radiotracers in prostate cancer, namely 18F-FDG, 18F- or 11C-acetate, and 18F- or 11C-choline.

18F-FDG Uptake in Lung, Breast, and Colon Cancers: Molecular Biology Correlates and Disease Characterization

It is hoped that in the not too distant future, noninvasive imaging–based molecular interrogation and characterization of tumors can improve our fundamental understanding of the dynamic biologic behavior of cancer. For example, the new dimension of diagnostic information that is provided by 18F-FDG PET has led to improved clinical decision making and management changes in a substantial number of patients with cancer. In this context, the aim of this review is to bring together and summarize the current data on the correlation between the underlying molecular biology and the clinical observations of tumor 18F-FDG accumulation in 3 major human cancers: lung, breast, and colon.

Competitive advantage of PET/MRI

Multimodality imaging has made great strides in the imaging evaluation of patients with a variety of diseases. Positron emission tomography/computed tomography (PET/CT) is now established as the imaging modality of choice in many clinical conditions, particularly in oncology. While the initial development of combined PET/magnetic resonance imaging (PET/MRI) was in the preclinical arena, hybrid PET/MR scanners are now available for clinical use. PET/MRI combines the unique features of MRI including excellent soft tissue contrast, diffusion-weighted imaging, dynamic contrast-enhanced imaging, fMRI and other specialized sequences as well as MR spectroscopy with the quantitative physiologic information that is provided by PET. Most evidence for the potential clinical utility of PET/MRI is based on studies performed with side-by-side comparison or software-fused MRI and PET images. Data on distinctive utility of hybrid PET/MRI are rapidly emerging. There are potential competitive advantages of PET/MRI over PET/CT. In general, PET/MRI may be preferred over PET/CT where the unique features of MRI provide more robust imaging evaluation in certain clinical settings. The exact role and potential utility of simultaneous data acquisition in specific research and clinical settings will need to be defined. It may be that simultaneous PET/MRI will be best suited for clinical situations that are disease-specific, organ-specific, related to diseases of the children or in those patients undergoing repeated imaging for whom cumulative radiation dose must be kept as low as reasonably achievable. PET/MRI also offers interesting opportunities for use of dual modality probes. Upon clear definition of clinical utility, other important and practical issues related to business operational model, clinical workflow and reimbursement will also be resolved.

Diagnostic role of [F-18]-FDG positron emission tomography in restaging renal cell carcinoma.

AIMS To retrospectively assess the diagnostic utility of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) in restaging renal cell carcinoma. MATERIALS AND METHODS We performed whole-body PET scans (45 minutes after intravenous injection of 10 - 15 mCi FDG) for restaging 25 patients (18 male, 7 female, 42 - 81 years old) with known or suspected metastatic renal cell carcinoma. Prior treatments included immunotherapy (n = 1), nephrectomy (n = 16), nephrectomy followed by chemotherapy (n = 3), by radiation therapy (n = 1), and by combined chemoradiation therapy (n = 4). Contrast-enhanced chest, abdomen and pelvis CT studies were available for all patients. Diagnostic validation was by histological sampling (n = 2) and clinical and imaging follow-up for up to 1 year (n = 23). RESULTS PET was concordant with the findings of CT in 18 patients (3 TN, 15 TP). PET was discordant with CT in 7 patients (28% of total). PET was falsely negative in 6 of these patients and did not demonstrate hypermetabolism in pulmonary (n = 4), mediastinal (n = 2), adrenal (n = 1) and lytic osseous (n = 2) metastatic lesions. PET was falsely positive in the remaining 1 patient in the discordant group with lumbar facet arthropathy. The diagnostic performance of PET in detection of recurrent and metastatic renal cell carcinoma revealed a sensitivity of 71%, specificity of 75%, accuracy of 72%, negative predictive value of 33% and positive predictive value of 94%. CONCLUSIONS FDG PET demonstrates modest accuracy in the diagnostic imaging evaluation of patients with suspected or known metastatic renal cell carcinoma. A negative study may not exclude disease while a positive study is suspicious for malignancy.

The SNMMI Practice Guideline for Therapy of Thyroid Disease with 131I 3.0

1UC Health University Hospital, Cincinnati, Ohio; 2Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania; 3Beaumont Health System, Royal Oak, Michigan; 4Guy’s Hospital, London, United Kingdom; 5Columbia University Medical Center, New York, New York; 6Cincinnati Children’s Medical Center, Cincinnati, Ohio; 7New York–Presbyterian/Weill Cornell Medical Center, New York, New York; 8University of Southern California, Los Angeles, California; 9University of California at Los Angeles, Los Angeles, California; 10Vanderbilt University Medical Center, Nashville, Tennessee; 11Beth Israel Deaconess Medical Center, Boston, Massachusetts; 12Mallinckrodt Institute of Radiology, St. Louis, Missouri; 13Jacobi Medical Center, Bronx, New York; 14Vanderbilt University, Nashville, Tennessee; and 15Cedars-Sinai Medical Center, Los Angeles, California

Molecular Imaging of Prostate Cancer: PET Radiotracers

OBJECTIVE Recent advances in the fundamental understanding of the complex biology of prostate cancer have provided an increasing number of potential targets for imaging and treatment. The imaging evaluation of prostate cancer needs to be tailored to the various phases of this remarkably heterogeneous disease. CONCLUSION In this article, I review the current state of affairs on a range of PET radiotracers for potential use in the imaging evaluation of men with prostate cancer.

Prospective evaluation of 18F-NaF and 18F-FDG PET/CT in detection of occult metastatic disease in biochemical recurrence of prostate cancer.

Purpose This study aimed to perform a prospective evaluation of 18F-NaF and 18F-FDG PET/CT in the detection of occult metastatic disease in men with prostate cancer and biochemical relapse. Methods Thirty-seven men with prostate-specific antigen (PSA) relapse (median, 3.2 ng/mL; range, 0.5–40.2 ng/mL) after definitive therapy for localized prostate cancer [26 radical prostatectomy (RP), 11 external beam radiation therapy] and negative conventional imaging underwent 18F-FDG and 18F-NaF PET/CT on 2 separate days within the same week. Studies were interpreted by 2 experienced radiologists in consensus for abnormal uptake suspicious for metastatic disease. The reference standard was a combination of imaging and clinical follow-up. Rank of PSA values for positive and negative PET/CT was compared using analysis of variance adjusting for primary therapy. Association between PSA and scan positivity in patients with RP was evaluated using Wilcoxon rank sum test. Results Result of the 18F-FDG PET/CT scan was positive for nodal disease in 2 patients. True-positive detection rate for occult osseous metastases by 18F-NaF PET/CT was 16.2%. Median PSA levels for positive versus negative PET/CT scans were 4.4 and 2.9 ng/mL, respectively, with the difference marginally significant in prostatectomized men (P = 0.072). Percentages of patients with either 18F-NaF– or 18F-FDG–positive PET/CT in RP and external beam radiation therapy were 10% (n = 10) and undefined (n = 0) for a PSA of 2 ng/mL or less, 29% (n = 7) and 50% (n = 2) for PSA greater than 2 ng/mL but 4 ng/mL or less, 60% (n = 5) and 40% (n = 5) for PSA greater than 4 ng/mL but 10 ng/mL or less, and 25% (n = 4) and 25% (n = 4) for PSA greater than 10 ng/mL, respectively. Conclusions In biochemical relapse of prostate cancer, 18F-NaF PET/CT is useful in the detection of occult osseous metastases, whereas the yield of 18F-FDG PET/CT is relatively limited. 18F-NaF PET/CT positivity tends to associate with increasing PSA level in prostatectomized men and may occur in lower PSA ranges than conventionally recognized.

Imaging Evaluation of Prostate Cancer with 18F-fluorodeoxyglucose PET/CT: Utility and Limitations

Prostate cancer is a major public health problem in developed countries. The remarkable biological and clinical heterogeneity of prostate cancer provides unique opportunities as well as challenges for the diagnostic imaging evaluation of this prevalent disease. The disease is characterized by a natural history that ranges from localized slowly growing hormone-dependent tumor progressing to metastatic hormone-refractory disease. PET is an ideal imaging tool for noninvasive interrogation of the underlying tumor biology. 18F-FDG is the most common PET radiotracer used for oncological applications based upon elevated glucose metabolism in malignant tissue in comparison to normal tissue. FDG uptake in prostate cancer depends on tumor differentiation with low accumulation in well-differentiated tumors and high uptake in aggressive poorly differentiated tumors. Cumulative current evidence suggests that FDG PET may be useful in detection of disease in a small fraction of patients with biochemical recurrence, in the imaging evaluation of extent and treatment response in metastatic disease and in prediction of patient outcome.

Evaluation of Recurrent Gastric Malignancy with (F-18)-FDG Positron Emission Tomography

AIM We retrospectively assessed the use of [(18)F] fluorodeoxyglucose positron emission tomography (FDG PET) in the evaluation of recurrent disease in patients with history of gastric malignancy. MATERIALS AND METHODS Eighteen patients were referred for FDG PET for evaluation of recurrent gastric cancer. Prior treatments included total (n = 4) or partial gastrectomy (n = 14) followed by chemotherapy alone (n = 7) or combined chemoradiation therapy (n = 2). The interval between the most recent treatment and PET ranged from 3 months to 2 years. Correlative diagnostic data were available in 16 patients and were all obtained within 3 months of the PET study. Validation was by clinical or imaging follow-up (2-45 months) in 16 patients and histology in two patients. RESULTS PET was concordant with computed tomography (CT) in 12 patients (5 TP, 6 TN, 1 FN). In one patient with negative imaging studies, an incidental finding of left obstructive uropathy was determined to be due to metastatic ureteral stricture. Discordant imaging findings were present in four patients (22% of total). PET-detected diffuse metastatic lesions in three of these patients with rising serum tumour markers while other imaging studies were negative. Additional chemotherapy was initiated in these three patients (17% of total) based on PET localization of disease. PET and a gastric anastomosis biopsy were negative in another patient with positive CT. The remaining two patients without correlative imaging studies died shortly after positive PET studies with presumed recurrent cancer. CONCLUSION FDG PET may be useful in the evaluation of recurrent gastric cancer, and can localize the disease when CT is non-diagnostic. Imaging evaluation with PET may also impact on the clinical management of patients with recurrent gastric cancer.

[F-18]fluorodeoxyglucose positron emission tomography and positron emission tomography: computed tomography in recurrent and metastatic cholangiocarcinoma.

Objectives: We retrospectively assessed the diagnostic utility of dedicated positron emission tomography (PET) and hybrid PET-computed tomography (CT) scans with [F-18]fluorodeoxyglucose (FDG) in the imaging evaluation of patients with known or suspected recurrent and metastatic cholangiocarcinoma. Methods: The study group included 24 patients (13 males and 11 females; age range, 34-75 years) with known or suspected recurrent and metastatic cholangiocarcinoma. We performed 8 dedicated PET scans (Siemens 953/A, Knoxville, Tenn) in 8 patients and 24 hybrid PET-CT scans (Siemens Biograph, Knoxville, Tenn) in 16 patients. Four patients underwent both pretreatment and posttreatment scans. Nonenhanced CT transmission scans were obtained for attenuation correction after administration of oral contrast material. PET images were obtained 60 minutes after the intravenous administration of 15 mCi (555 MBq) FDG. Prior treatments included surgery alone in 12 patients, surgery and chemotherapy in 6 patients, and surgery and combined chemoradiation therapy in 6 patients. Diagnostic validation was conducted through clinical and radiologic follow-up (2months to 8 years). Results: PET and CT were concordant in 18 patients. PET-CT correctly localized a hypermetabolic metastatic lesion in the anterior subdiaphragmatic fat instead of within the liver and was falsely negative in intrahepatic infiltrating type cholangiocarcinoma. PET was discordant with CT in 6 patients. PET was negative in an enlarged right cardiophrenic lymph node on CT, which remained stable for 1 year. In 1 patient, PET-CT scan showed hypermetabolic peritoneal disease in the right paracolic gutter without definite corresponding structural abnormalities, which was subsequently confirmed on a follow-up PET-CT scan performed 6 months after the initial study, at which time peritoneal nodular thickening was evident on concurrent CT. PET-CT documented the progression of locally recurrent and metastatic disease in another patient based on interval appearance of several new hypermetabolic lesions and significant increase in the standardized uptake values of the known lesions despite little interval change in the size and morphologic character of lesions on concurrent CT. It was also helpful in excluding metabolically active disease in patients with contrast enhancement at either surgical margin of hepatic resection site or focally within hepatic parenchyma and in an osseous lesion. Overall, based on the clinically relevant patient basis for detection of recurrent and metastatic cholangiocarcinoma, the sensitivity and specificity of PET (alone and combined with CT) were 94% and 100% and, for CT alone, were 82% and 43%, respectively. Conclusions: FDG PET and PET-CT are useful in the imaging evaluation of patients with cholangiocarcinoma (except for infiltrating type) for detection of recurrent and metastatic disease and for assessment of treatment response. In particular, the combined structural and metabolic information of PET-CT enhances the diagnostic confidence in lesion characterization.