Characteristics and Limitations of FDG PET/CT for Imaging of Squamous Cell Carcinoma of the Head and Neck: A Comprehensive Review of Anatomy, Metastatic Pathways, and Image Findings.

OBJECTIVE: This image-based article illustrates the anatomic regions of squamous cell carcinomas of the head and neck and describes the metastatic pathways in and TNM staging for each region. Both the role and limitations of FDG PET/CT in imaging such cancers are discussed, and cases exemplifying these issues are reported. Also included is a discussion of the use of FDG PET/CT to monitor the response of squamous cell carcinomas of the head and neck to therapy, in addition to a brief comparison of PET/CT with such traditional imaging modalities as CT, MRI, and ultrasound. CONCLUSION: Understanding the characteristics of squamous cell carcinoma of the head and neck, as imaged by FDG PET/CT, is crucial for determining treatment strategy, because it helps to avoid incorrect staging and also provides an accurate assessment of treatment response.

A simple method for estimating dose delivered to hepatocellular carcinoma after yttrium-90 glass-based radioembolization therapy: preliminary results of a proof of concept study.

PURPOSE: To investigate a simple semiquantitative method to estimate yttrium-90 ((90)Y) dose delivered with radioembolization to infiltrative hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In a prospective study, patients with infiltrative HCC and portal vein thrombosis (PVT) underwent glass-based (90)Y radioembolization including technetium-99m macroaggregated albumin ((99m)Tc-MAA) hepatopulmonary shunt study before therapy and bremsstrahlung single photon emission computed tomography (SPECT)/computed tomography (CT) after (90)Y radioembolization. Baseline magnetic resonance imaging was coregistered with (99m)Tc-MAA and bremsstrahlung SPECT/CT imaging separately. Unit tumor activity ((90)Y radioactivity delivered to each cubic centimeter of tumor) was estimated based on a lobar infusion approach. Correlation between proportions of (99m)Tc-MAA and (90)Y delivered to the tumor was investigated. Survival analysis was performed using Kaplan-Meier estimations. RESULTS: (90)Y therapy was administered in 18 consecutive patients (median age, 55.3 y; mean tumor volume, 588 cm(3)). Higher intratumoral (90)Y dose predicted prolonged survival, with 13.2-month median survival in patients with HCC and mean (90)Y dose of ≥ 100 Gy versus 4.6-month median survival for other patients (P < .001). Of administered (90)Y dose, 51.9% was delivered to the targeted tumors compared with 74.1% of (99m)Tc-MAA with linear correlation between biodistribution of (99m)Tc-MAA and (90)Y observed (Pearson r = 0.774, P < .001). CONCLUSIONS: The findings in this study suggest that approximately 50% of administered (90)Y dose is taken up by targeted infiltrative HCC with PVT. Intratumoral (90)Y dose ≥ 100 Gy in unresectable infiltrative HCC via a lobar intraarterial approach is a positive prognostic factor for survival.

Radiologic reporting: the ethical obligation of the interpreting physician to provide an accurate report.

OBJECTIVE: This article focuses on the radiology report and examines how related errors can affect patient care even though the radiologist might resist disclosing or discussing reporting errors in a patient-centered way. By using scenarios involving issues in reporting, we hope to show how various ethical theories support the obligation of a radiologist to provide an honest, complete report and to ensure that errors are disclosed to patients. CONCLUSION: Radiologists should be willing to make corrections when necessary and ethical theories and principles are available to guide them in their duty to care for their patients. Physicians owe it to their patients, their patients' families, and the medical profession to produce an honest and truthful report. Despite temptations to deviate from ethically appropriate action, physicians must make honesty to their patients and reporting of errors a priority. Few patients expect absolute perfection from their physicians, but honesty and truthfulness in reporting will advance physician-patient and physician-physician relationships and can foster optimal patient care.

Prognostic value of 18f-fluorodeoxyglucose positron emission tomography-computed tomography in predicting survival in patients with unresectable metastatic melanoma to the liver undergoing yttrium-90 radioembolization.

PURPOSE: To investigate the prognostic value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) in predicting survival in patients with unresectable metastatic melanoma to the liver undergoing yttrium-90 ((90)Y) radioembolization. MATERIALS AND METHODS: A retrospective review of 12 patients with unresectable hepatic melanoma metastases (5 patients with cutaneous metastases, 7 patients with ocular metastases) who underwent (18)F-FDG PET-CT before (90)Y was performed. Metabolically significant tumors, defined as having a long-axis diameter ≥ 1 cm and maximum standardized uptake value (SUV(max)) ≥ 2.5, were identified on (18)F-FDG PET-CT. SUV(max), glycolytic activity, and volume were determined for each tumor. Overall SUV(max), total tumor glycolytic activity (TGA), total metabolic tumor volume (MTV), and metabolic tumor burden (MTB) based on percentage of liver involvement (MTV/total liver volume) were calculated. Kaplan-Meier method, life-table analysis, and Cox proportional hazards model were used for statistical analysis. RESULTS: Median SUV(max) was 10.9 (range, 4.6-15.3), median TGA was 377.0 SUV/cm(3) (range, 53.6-20,393.4 SUV/cm(3)), median MTV was 85.4 cm(3) (range, 11.5-2,504.1 cm(3)), and median MTB was 5.5% (range, 0.1%-54.0%). MTB was found to be a significant negative prognostic marker of survival on univariate (P = .020) and multivariate (P = .018) analyses accounting for age and duration from metastatic diagnosis to first (90)Y treatment. A 60th percentile MTB of 7.0% (hazard ratio, 5.704; P = .040) was a statistically significant cutoff. Median survivals from first (90)Y treatment in patients with MTB < 7.0% and ≥ 7.0% were 10.8 months (95% confidence interval [CI], 6.8-14.8) and 4.7 months (95% CI, 1.6-7.8), respectively. SUV(max) (P = .422), TGA (P = .064), and MTV (P = .065) were not found to be statistically significant. CONCLUSIONS: MTB based on (18)F-FDG PET-CT performed before treatment was found to be a negative prognostic factor for patient survival after (90)Y radioembolization for unresectable metastatic melanoma to liver.

Does colon cancer ever metastasize to bone first? a temporal analysis of colorectal cancer progression.

BACKGROUND: It is well recognized that colorectal cancer does not frequently metastasize to bone. The aim of this retrospective study was to establish whether colorectal cancer ever bypasses other organs and metastasizes directly to bone and whether the presence of lung lesions is superior to liver as a better predictor of the likelihood and timing of bone metastasis. METHODS: We performed a retrospective analysis on patients with a clinical diagnosis of colon cancer referred for staging using whole-body 18F-FDG PET and CT or PET/CT. We combined PET and CT reports from 252 individuals with information concerning patient history, other imaging modalities, and treatments to analyze disease progression. RESULTS: No patient had isolated osseous metastasis at the time of diagnosis, and none developed isolated bone metastasis without other organ involvement during our survey period. It took significantly longer for colorectal cancer patients to develop metastasis to the lungs (23.3 months) or to bone (21.2 months) than to the liver (9.8 months). CONCLUSION: Metastasis only to bone without other organ involvement in colorectal cancer patients is extremely rare, perhaps more rare than we previously thought. Our findings suggest that resistant metastasis to the lungs predicts potential disease progression to bone in the colorectal cancer population better than liver metastasis does.

Tumor blood flow measured by perfusion computed tomography and 15O-labeled water positron emission tomography: a comparison study.

OBJECTIVES: To compare blood flow measurements of tumors assessed by perfusion computed tomography (pCT) and the clinical gold standard of 15O-labeled water positron emission tomography (15O-PET). METHODS: Blood flows were estimated by pCT (4-row multidetector, CT Perfusion 3.1) and 15O-PET (Posicam, first-pass model) in 14 patients with solid tumors, totaling 22 index tumors and 57 matched pairs of examinations. Blood flow estimates were compared using t test, Bland-Altman, and linear mixed regression analyses. RESULTS: There was no significant difference between the mean (SD) blood flow values measured by pCT and 15O-PET: 25.9 +/- 15.4 and 27.8 +/- 14.0 mL/min per 100 g, respectively. CONCLUSIONS: The demonstration of a good correlation between pCT and 15O-PET potentially enables the use of pCT, which is more widely available than 15O-PET, when tumor blood flow estimates are required, particularly in the context of clinical studies.

Tumor blood flow measured by PET dynamic imaging of first-pass 18F-FDG uptake: a comparison with 15O-labeled water-measured blood flow.

UNLABELLED: PET molecular imaging of 15O-labeled water is the gold standard for measuring blood flow in humans. However, this requires an on-site cyclotron to produce the short-lived 15O tracer, which is cost-prohibitive for most clinical PET centers. The purpose of this study was to determine if the early uptake of 18F-FDG could be used to measure regional blood flow in tumors in the absence of 15O-water. METHODS: PET scans were obtained in patients being evaluated for tumor perfusion and glucose metabolism in a phase I dose-escalating protocol for endostatin, a novel antiangiogenic agent. A 2-min perfusion scan was performed with a bolus injection of 2,220 MBq (60 mCi) of 15O-water, which was followed by a 370-MBq (10 mCi) dose of 18F-FDG. Four sequential scans of 18F-FDG uptake were acquired, consisting of an early 2-min uptake scan-or first-pass scan-and 3 sequential 15-min late 18F-FDG uptake scans. Regions of interest (ROIs) were drawn on 2 or more tumor sites and on back muscle, as a control ROI, for each patient. Arterial blood concentration was derived from the PET scans by drawing an ROI over a large artery in the field of view. Blood flow was computed with a simple 1-compartment blood flow model using the first 2 min of data after injection. RESULTS: Blood flow estimated from the early uptake of 18F-FDG was linearly correlated with 15O-measured blood flow, with an intercept of 0.01, a slope of 0.86, and an R2 regression coefficient of 0.74 (r = 0.86). The 18F-FDG tumor extraction fraction relative to 15O-water averaged 0.86. A preliminary case study of a patient with prostate cancer confirms the utility of the first-pass 18F-FDG blood flow analysis in tumor diagnosis. CONCLUSION: These results suggest that the first-pass uptake of 18F-FDG may provide an estimate of perfusion in a tumor within the limitations of incomplete extraction of 18F-FDG compared with 15O-water.

Oncologic 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography: What All Physicians Need to Know.

Fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) hybrid examinations (PET/computed tomography, PET/magnetic resonance imaging) have become the most common PET imaging tools in the evaluation of the oncologic patient. Therefore it is of paramount importance that physicians who take care of oncology patients in any capacity are familiar with the basics of when these examinations are indicated, know how to best prepare the patients, and understand the benefits and limitations of the procedure. Additionally, it is important to understand which medical conditions and medications need to be controlled to maintain the diagnostic accuracy of these tests. In this article we aim to explain what 18F-FDG is, how to best prepare our patients, what PET is, and how these examinations are interpreted. Finally, we discuss some of the limitations of these examinations.

(18)F-Fluorodeoxy glucose (FDG) uptake in nontraumatic bilateral adrenal hemorrhage secondary to heparin-associated thrombocytopenia syndrome (HATS) - a case report.

(18)F-Fluorodeoxy glucose (FDG) activity reflects tissue glucose metabolism; malignancies, metastases, and acute infections have relatively increased FDG activity reflecting increased glucose metabolism. Benign adrenal disease demonstrating mild FDG uptake can be worrisome for metastasis in patients with a history of malignancy. Our patient with breast and colon cancer developed gastrointestinal bleeding on heparin therapy, enlarged adrenals with heterogeneous attenuation consistent with hemorrhage and blood clots as seen on abdominal computed tomography scan, and as abnormal intense FDG activity in the bilateral adrenal glands on positron emission tomography scan.

99mTc-Sestamibi Avid Soft Tissue Lesions in Rosai-Dorfman Disease.

Langerhan's histiocytosis is a not uncommon disease, but a related disorder, Rosai-Dorfman (RDD) with extensive or exclusive extranodal distribution, is relatively rare. Ga and PET/CT imaging have typically been used for diagnosis and tracking response to treatment. The authors present a very unusual case wherein lesions of RDD actively accumulated Tc-sestamibi, which was injected as part of a scan to localize a parathyroid adenoma.

Rim sign in Tc-99m sulfur colloid hepatic scintigraphy.

A case of pericholecystic hyperperfusion on Tc-99m sulfur colloid (SC) flow images with a pericholecystic rim of increased activity (PCHA) on delayed planar and single-photon emission computed tomography images of the liver was seen in a patient with a history of multiple renal transplants admitted with cramping right lower quadrant abdominal pain. Laparotomy performed 5 days after the scan revealed an acutely perforated gangrenous gallbladder and occluded cystic duct. The secondary findings of gallbladder hyperperfusion and PCHA or "rim sign" have been frequently reported with Tc-99m IDA hepatobiliary imaging. These secondary findings in conjunction with a nonvisualized gallbladder on an IDA scan suggest a complicated or advanced stage of acute cholecystitis and usually require urgent surgical intervention. The rim sign on Tc-99m SC scintigraphy also likely indicates the same grave diagnosis.

The nuclear medicine therapy care coordination service: a model for radiologist-driven patient-centered care.

We developed a longitudinal care coordination service to proactively deliver high-quality and family-centered care in patients receiving radioiodine therapy for thyroid cancer. In an iterative, multidisciplinary team manner, a pretherapy consultation service, which included scripted interactions, documentation, and checklists for quality control, evolved over time into a robust patient-centered longitudinal care coordination nuclear medicine service. Radiation safety precautions, the rationale for therapy, and management of patient expectations were addressed through the initial consultation, and discharge and posttreatment care were managed during subsequent follow-up. The patient-physician relationship created during longitudinal nuclear medicine therapy care is one tool to help counteract the growing commoditization of radiology. This article describes the process that the nuclear medicine specialists in our department established to enhance radiologist value by providing both exceptional thyroid cancer treatment and continuity of care.

Ethical dilemmas in today's nuclear medicine and radiology practice.

Throughout history, societies have developed their own codes of ethics, including those pertaining to the practice of medicine. In the United States, physicians have adopted a set of ethics based on religious values and historical teachings. We, as physicians, have been presented several codes of ethics, including the American Medical Association Code of Ethics and the American College of Radiology Code of Ethics. Over time, we have learned to appropriately apply these codes to our daily practice. With the advent of new technologies in imaging, we may lose sight as to the transfer of these principles to reflect current conditions. Recent history has shown a trend of new technology leading to potential misuse of this technology and further leading to stricter governmental regulations. It is the purpose of this review to give guidelines for dealing with new technologies, such as PET imaging, and we describe a radiologist's ethical responsibility in a doctor-patient relationship. A historical review of medical ethics will lead to discussions about various issues affecting radiologists and nuclear physicians. To be sure, not all ethical situations are black and white, and therefore there are many gray areas. The opinions expressed in this article are those of the authors and are based on extension of already established rules of ethical conduct.

Multimodality imaging of aortitis.

Multimodality imaging of aortitis is useful for identification of acute and chronic mural changes due to inflammation, edema, and fibrosis, as well as characterization of structural luminal changes including aneurysm and stenosis or occlusion. Identification of related complications such as dissection, hematoma, ulceration, rupture, and thrombosis is also important. Imaging is often vital for obtaining specific diagnoses (i.e., Takayasu arteritis) or is used adjunctively in atypical cases (i.e., giant cell arteritis). The extent of disease is established at baseline, with associated therapeutic and prognostic implications. Imaging of aortitis may be useful for screening, routine follow up, and evaluation of treatment response in certain clinical settings. Localization of disease activity and structural abnormality is useful for guiding biopsy or surgical revascularization or repair. In this review, we discuss the available imaging modalities for diagnosis and management of the spectrum of aortitis disorders that cardiovascular physicians should be familiar with for facilitating optimal patient care.

MIBG superscan of metastatic paraganglioma occurring with neurofibromatosis type 1.

A Tc MDP bone superscan occurs when osseous activity is extremely intense and genitourinary and soft tissue activity is not identified. A similar phenomenon has been described with metaiodobenzylguanidine (MIBG) in metastatic pheochromocytoma and neuroblastoma. We present a case of metastatic paraganglioma resulting in an MIBG superscan. Neuroendocrine bone metastasis alters the biodistribution of MIBG such that the liver, heart, and urinary bladder are not well visualized. Our case occurred in association with neurofibromatosis type 1 and in the absence of an identified primary tumor.

Unusual case of emphysematous cystitis seen on FDG PET/CT.

Emphysematous cystitis is a rare condition requiring immediate aggressive medical attention. Here, we describe a very unusual case of emphysematous cystitis seen on FDG PET/CT. This finding was discovered in an 84-year-old man undergoing FDG PET/CT to monitor a known diagnosis of IgG4-related nodular sclerosis. Images revealed gas within the bladder wall and an anterior gas-filled bladder diverticulum. The patient subsequently developed sepsis with cultures revealing Escherichia coli. This case highlights the importance of recognizing this finding on varied imaging modalities, as life-threatening complications may arise from this condition.

Inguinal herniation of a bladder diverticulum on PET/CT and associated complications.

Inguinal herniation of the urinary bladder is not routinely seen in clinical practice. Most patients are asymptomatic and are diagnosed incidentally on diagnostic imaging or during the course of surgical repairs. Bladder herniation has previously been reported on ultrasonography and computed tomography, but not on positron emission tomography (PET) imaging. We report an interesting case of bladder herniation and describe the findings observed by PET as well as the complications associated with this abnormality.