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ABSTRACT: An 81-year-old man with prostate adenocarcinoma demonstrated interval progression of the osteoblastic metastatic disease on surveillant bone scan with a new lumbar lesion resembling the configuration of Mickey's head (Mickey Mouse sign), a sign considered to be specific for Paget disease, even in the presence of malignancy. However, our case demonstrates that this appearance can be caused by other etiologies. In the era of SPECT/CT and MRI, it is prudent to obtain further cross-sectional correlation at the time of radionuclide bone scintigraphy to clarify the underlying cause for "Mickey Mouse sign" to prevent misinterpretation, allowing for efficient and accurate patientcare.

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Although tumor lysis syndrome is well described, it is rarely seen or suspected in solid malignancies. Early recognition of this entity is paramount in reducing morbidity and mortality. Treating physicians should be aware of this possibility in solid tumor patients with either bulky disease or extensive liver involvement.

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BACKGROUND: The primary objective of this study was to evaluate the utility of fluorodeoxyglucose positive emission tomography imaging in assessing the degree of joint inflammation and response to therapy in patients with rheumatoid arthritis using standard PET parameters. METHODS: Five subjects with newly diagnosed RA were enrolled in this IRB-approved prospective study. After standard conventional workup that included clinical and laboratory evaluation and disease activity score (DAS3v) calculation, subjects underwent baseline FDG PET scans of their hands and feet prior to initiation of treatment and after six months of standard treatment. The uptake of FDG in involved joints was assessed qualitatively (visual evaluation) as well as semi quantitatively using standardized uptake value (SUV). Findings from the FDG PET scans were correlated with clinical and laboratory parameters including DAS and ESR. RESULTS: In all five patients, increased FDG uptake was noted in various joints affected by RA. The intensity of uptake varied from mild to intense (SUVmax values from 3.10 to 6.0). Overall, these correlated well with the clinical evaluation of involved joints. FDG PET imaging provided additional information by showing involvement in joints that were difficult to evaluate clinically (e.g. mid foot joints). The PET data also provided a distribution of joint involvement with varying degrees of severity in the same subject. On objective analysis using Spearman rank correlation coefficient for statistical analysis, no significant correlations were observed (p>0.05) between DAS, ESR, and the different PET parameters at baseline (before treatment) despite large calculated positive correlation coefficients. This was due to the small sample size (n=5). At post-treatment, the significant correlations were those between DAS and Maximum metabolic disease burden (MDB max) (RS=0.9, p=0.04) and between ESR and MDB max (RS=0.9, p=0.04). The positive correlations between total metabolic disease burden (Total MDB) and DAS (RS=0.7) and between Total MDB and ESR were also large (RS=0.7) but not significant. The non-significance was due to the small sample size. CONCLUSIONS: FDG PET imaging provides a unique noninvasive quantitative method in assessing disease status and response to therapy and can serve as a useful adjunct to clinical evaluation in management of patients with rheumatoid arthritis.

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BACKGROUND: Skeletal muscle metastases (SMM) are a rare occurrence despite the fact that skeletal muscle comprises more than 50% of total body mass. When present, most are asymptomatic and are often found incidentally on imaging. Several studies have reported isolated cases of patients with SMM. The goal of our study was to perform a comprehensive retrospective analysis of the incidence, frequency, and source of SMM in patients with malignancies who underwent whole-body FDG PET/CT imaging for the workup for their malignancy. METHODS: The records of 8492 consecutive patients referred for oncologic imaging at our institution during the period from January 2006 to December 2009 were reviewed. Patients who had SMM on FDG PET imaging were further assessed for collaborating evidence on other imaging modalities, pathology from tissue sampling, and follow-up scans. The incidence of SMM in our setting was calculated, and their association with various primary malignancies was also evaluated. RESULTS: A total of 73 patients with SMM were identified on PET/CT imaging (incidence, 0.86%). Lung cancer was the most frequent source (25 patients [34%]), followed by gastrointestinal tract malignancies (13 patients [18%]), breast cancer (10 patients [14%]), genitourinary malignancies and lymphoma (6 patients [8%] each), melanoma (5 patients [7%]), and other miscellaneous malignancies (3 patients [4%]). Primary source remained unknown in only 5 patients (7%). Most patients with SMM generally had markedly widespread involvement which led to an unusual appearance on FDG PET/CT imaging. However, since most of these patients had stage IV malignant disease by virtue of visceral metastases elsewhere as well, they were generally not upstaged. CONCLUSIONS: Our study confirmed the rare occurrence of SMM. Furthermore, FDG PET/CT can potentially detect unsuspected SMM. Interestingly, in our patient population, lung cancer was found to be the most frequent malignancy metastasizing to the skeletal muscles. Knowledge about the presence and appearance of widespread SMM may aid in appropriate interpretation of FDG PET/CT scans.

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Incidental findings are not infrequent on integrated FDG PET/CT scans by the virtue of obtaining images from skull base to mid thigh. These can be on the FDG PET portion or the CT portion of the study and can be clinically significant. We report a case of FDG PET/CT imaging performed for staging of head and neck cancer that led to the detection of unsuspected pulmonary embolism. Our case reinforces the importance of careful interpretation of incidental findings on FDG PET/CT imaging as they can have a significant effect on patient management.

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UNLABELLED: The purpose of this study was to estimate the fetal radiation exposure resulting from (18)F-FDG PET procedures performed in pregnant patients with malignancies. METHODS: Five pregnant patients with a biopsy-proven diagnosis of malignancy who underwent (18)F-FDG PET studies were retrospectively reviewed. All patients underwent PET-only studies (and not PET/CT studies) with a reduced (18)F-FDG dose (except for 1 patient who had a negative pregnancy test immediately before the (18)F-FDG PET procedure but was confirmed to be pregnant a few weeks later), including vigorous hydration and diuresis to minimize radiation exposure to the fetus. One patient underwent (18)F-FDG PET twice during her pregnancy (in the second and third trimesters). Fetal radiation dose was independently assessed for each patient, and an analysis was made of fetal radiation doses using the measurements of activity in the fetuses at various stages of pregnancy. RESULTS: Six (18)F-FDG PET studies in 5 pregnant patients were analyzed. The (18)F-FDG PET scans were obtained in early pregnancy (n = 1), the second trimester (n = 2), and the third trimester (n = 3). The fetal dose exposure from (18)F-FDG PET studies was estimated to range from 1.1 to 2.43 mGy for various trimesters in pregnancy (except for the patient in the early stage of pregnancy, in whom activity in the whole uterus was considered, and the fetal dose was estimated to be 9.04 mGy). All patients delivered healthy infants with no visible abnormalities at term. CONCLUSION: The fetal radiation dose from (18)F-FDG PET studies is quite low and significantly below the threshold dose for deterministic effects due to radiation exposure to the fetus. The estimated fetal radiation exposure in our cases was slightly lower than existing estimates on fetal dose exposure, and as more data become available, the current fetal dose estimates may have to be modified accordingly. By addressing an important safety issue dealing with performing medically necessary (18)F-FDG PET in pregnant patients, these data are expected to help in the imaging workup of cancer patients during pregnancy.

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As the limits of existing treatments for cancer are recognized, clearly novel therapies must be considered for successful treatment; cancer therapy using adenovirus vectors is a promising strategy. However tracking the biodistribution of adenovirus vectors in vivo is limited to invasive procedures such as biopsies, which are error prone, non-quantitative, and do not give a full representation of the pharmacokinetics involved. Current non-invasive imaging strategies using reporter gene expression have been applied to analyze adenoviral vectors. The major drawback to approaches that tag viruses with reporter genes is that these systems require initial viral infection and subsequent cellular expression of a reporter gene to allow non-invasive imaging. As an alternative to conventional vector detection techniques, we developed a specific genetic labeling system whereby an adenoviral vector incorporates a fusion between capsid protein IX and human metallothionein. Our study herein clearly demonstrates our ability to rescue viable adenoviral particles that display functional metallothionein (MT) as a component of their capsid surface. We demonstrate the feasibility of (99m)Tc binding in vitro to the pIX-MT fusion on the capsid of adenovirus virions using a simple transchelation reaction. SPECT imaging of a mouse after administration of a (99m)Tc-radiolabeled virus showed clear localization of radioactivity to the liver. This result strongly supports imaging using pIX-MT, visualizing the normal biodistribution of Ad primarily to the liver upon injection into mice. The ability we have developed to view real-time biodistribution in their physiological milieu represents a significant tool to study adenovirus biology in vivo.

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FDG PET imaging is generally not useful for prostate cancer. Nevertheless, incidental intense FDG uptake in the prostate warrants further evaluation to assess for prostatic malignancy. We report a case where intense FDG uptake was incidentally noted in an enlarged prostate on FDG PET/CT scan performed for a large left hilar/mediastinal mass (that was also intensely FDG avid along with several additional FDG-avid lesions elsewhere). Biopsy of the prostate and mediastinal lesions revealed large B-cell non-Hodgkin lymphoma at both sites. Serial FDG PET/CT imaging in this patient revealed that the prostatic lymphomatous lesions showed a slower and incomplete response to chemotherapy compared with other sites of lymphomatous involvement (that showed a rapid and complete response to chemotherapy) in the same patient.

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Evidence from the medical literature supports the use of Cardiac positron emission tomography (PET) scanning to assess myocardial viability in patients with severe Left ventricular dysfunction who are being considered for revascularization. Cardiac PET has emerged as an alternative to Single Photon Emission Computed Tomography (SPECT) imaging for assessment of Coronary Artery Disease. PET scanning is less likely than SPECT scanning to provide indeterminate results. The aim of the present paper is to review existing literature on relative merits of Cardiac PET imaging.

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FDG-PET imaging, which is routinely used to assess recurrent breast cancer, is nonspecific for malignancies and can detect several inflammatory lesions. Costochondritis following breast reconstructive surgery, presenting with excruciating chest pain or "chondrodynia," is a rare variant of Tietze's syndrome thought to occur due to traction exerted by large breast implants. Diagnosis is usually clinical because no abnormalities are identified on conventional imaging. Two cases have been reported in the literature, but none with FDG-PET. We report a patient with treated breast cancer, presenting with chest pain where FDG-PET to assess for recurrence was consistent with costochondritis and peri-implant inflammation.

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Positron emission tomography (PET) with 2-fluoro-deoxyglucose (FDG) has become an established imaging modality that can accurately and noninvasively differentiate malignant neoplasms from benign masses. It is increasingly being used to grade malignant neoplasms as well and has almost replaced other studies like gallium 67-citrate scans for metabolic imaging. We describe an interesting case of 3 synchronous liposarcomas with different radio-opacifications on computed tomography (CT). The more aggressive lesion with more opacity on CT showed intense FDG activity and was found to be a high-grade liposarcoma on pathology. The well-differentiated lesion with more fat content appearing less radio-opaque on CT showed almost no FDG activity and an intermediate grade lesion with intermediate radio-opacity on CT showed mildly increased FDG activity. Dual modality imaging with integrated PET/CT systems have strengthened the confidence of classifying these lesions even before knowing the pathology as depicted in this case.

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Fibrosing mediastinitis is an uncommon benign disorder, and its pathogenesis and management remain unclear. Conventional imaging techniques (chest radiographs, CT, MRI) may suggest its diagnosis but are frequently nonspecific, and it frequently mimics a malignant process by presenting as a mediastinal mass without calcifications, encasing, and infiltrating adjacent mediastinal structures, and showing an overall aggressive behavior. The value of FDG PET imaging in this entity remains largely unknown with only a few case reports in the literature, and often, biopsy is necessary for definitive diagnosis. We report a case of biopsy proven fibrosing mediastinitis highlighting the utility of PET in the evaluation and management of the disease.

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This study was performed to assess the binding kinetics of a targeted microbubble contrast agent exposed to shear stress. An ultrasound contrast targeted to P-selectin was designed by conjugating monoclonal antibodies against murine P-selectin (RB40.34) to the lipid monolayer shell of the microbubble using poly(ethylene glycol)-biotin-streptavidin. The attachment and detachment of targeted microbubbles to P-selectin immobilized on a culture dish were assessed in a parallel-plate flow chamber. Targeted microbubbles (5 x 10(6) particles/ml) drawn through the flow chamber coated with P-selectin (109 sites/microm(2)) at a shear stress of 0.3 dyn/cm(2) accumulated at a rate of 565 mm(-2) min(-1). Attachment rates increased at higher plate surface densities of P-selectin, and microbubble detachment was reduced. Accumulation rate first increased with shear stress, reached a maximum at approximately 0.6 dyn/cm(2) and then decreased. Control experiments on a plate that lacked P-selectin, or was blocked with mAb RB40.34, resulted in minimal bubble attachment. Microbubble detachment was tested by ramping up shear stress at 30-s intervals. Half-maximal detachment was reached at 34 dyn/cm(2). Overall, accumulation and retention of targeted ultrasound contrast agents is possible under physiologic flow conditions and is strongly influenced by shear stress and surface density of the target receptor.

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