In Vivo Molecular Imaging of Musculoskeletal Inflammation and Infection.

In vivo molecular imaging detects biologic processes at molecular level and provides diagnostic information at an earlier time point during disease onset or repair. It offers definite advantage over anatomic imaging in terms of improved sensitivity and ability to quantify. Radionuclide molecular imaging has been widely used in clinical practice. This article discusses the role of radionuclide imaging in various infective and inflammatory diseases affecting musculoskeletal system with a focus on PET. It appears that, as more data become available, combined PET/MR imaging could emerge as a front runner in the imaging of musculoskeletal infection and inflammation.

Contrast-enhanced [18F] fluorodeoxyglucose-positron emission tomography-computed tomography as an initial imaging modality in patients presenting with metastatic malignancy of undefined primary origin.

BACKGROUND: To evaluate the advantages of contrast enhanced F-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-contrast enhanced CT [CECT]) when used as an initial imaging modality in patients presenting with metastatic malignancy of undefined primary origin (MUO). MATERIALS AND METHODS: A total of 243 patients with fine needle aspiration cytology/biopsy proven MUO were included in this prospective study. Patients who were thoroughly evaluated for primary or primary tumor was detected by any other investigation were excluded from the analysis. Totally, 163 patients with pathological diagnosis of malignancy but no apparent sites of the primary tumor were finally selected for analysis. The site of probable primary malignancy suggested by PET-CECT was confirmed by biopsy/follow-up. RESULTS: PET-CECT suggested probable site of primary in 128/163 (78.52%) patients. In 30/35 remaining patients, primary tumor was not detected even after extensive work-up. In 5 patients, where PET-CECT was negative, primary was found on further extensive investigations or follow-up. The sensitivity, specificity, positive predictive value and negative predictive value of the study were 95.76%, 66.67%, 88.28% and 85.71% respectively. CONCLUSIONS: F-18 FDG PET-CECT aptly serves the purpose of initial imaging modality owing to high sensitivity, negative and positive predictive value. PET-CECT not only surveys the whole body for the primary malignancy but also stages the disease accurately. Use of contrast improves the diagnostic utility of modality as well as help in staging of the primary tumor. Although benefits of using PET-CECT as initial diagnostic modality are obvious from this study, there is a need for a larger study comparing conventional methods for diagnosing primary in patients with MUO versus PET-CECT.

Role of 2-Fluoro-2-Deoxyglucose PET/Computed Tomography in Carcinoma of Unknown Primary.

FDG-PET/CT is a potentially useful imaging modality in the setting of Carcinoma of Unknown Primary (CUP) from various aspects. The central question is detection of site of primary, where most studies have documented the pooled sensitivity and specificity of FDG PET/CT in the range of 80%-85% and a tumor detection rate (after the failure of conventional imaging procedures) between 30%-37%. The heterogeneity in the (i) population studied and (ii) criteria used for labelling patient as of unknown primary, have been the prime reason for widely varying result amongst various studies. Initiating appropriate treatment strategies owing to simultaneous whole body disease staging can be regarded an added utility PET/CT, even in the case of failure of primary tumor detection. FDG-PET/CT changed the patient management in around 35% of patients (studies reporting heterogeneous results ranging from 18.2% to 60%). The futuristic approach will be to monitor molecular targeted and cystostatic therapies with FDG-PET/CT which obviously has advantages than anatomical imaging alone.

Monoarticular carcinomatous knee joint arthritis as an initial presentation of cervical carcinoma.

When it comes to cancer, one can expect the unexpected. The clinical presentations can be very bizarre. One of these uncommon presentations is monoarticular arthritis. The age group affected by cancer and arthritis are similar. However, the possibility of joint pain being secondary to metastatic involvement does not come to mind easily. In this report, a 65-year-old postmenopausal woman presented with complaint of pain and restricted movement of the right knee joint, in whom the clinical and magnetic resonance imaging features were suggestive of infective monoarthritis. However, synovial fluid aspirate showed presence of malignant cells. Hence, patient was evaluated with whole-body (18)F-fluorodeoxyglucose positron emission tomography computed tomography which detected primary malignancy of the cervix with regional nodal and right knee joint metastasis. To our knowledge, this is the first reported case of cervical malignancy with solitary skeletal metastasis involving the knee joint. The report also discusses overall incidence of malignant arthritis.

SPECT in asymptomatic diabetics with and without microalbuminuria.

OBJECTIVE: To identify coronary artery disease (CAD) in asymptomatic diabetics with the help of myocardial perfusion single photon emission computed tomography (MPS), a non-invasive imaging modality and its correlation in diabetics with or without microalbuminuria. METHODS: This study included 99 patients in the age group of 30 to 80 years who were asymptomatic but possessed one or more risk factors for CAD. These patients were divided into two groups, diabetics with and without microalbuminuria (Micral). Thirty eight patients were Micral positive and 61 were Micral negative. Ischemia was detected by MPS and compared with coronary angiographic findings in both the groups. RESULTS: Amongst the 99 diabetic patients, MPS was positive in 39 patients. Out of 39 MPS positive patients, 31(79.5%) were micral positive and 8 (20.5%) were micral negative. Out of 38 micral positive patients, 31 patients were positive on MPS and 27 had significant angiographic (CAG) findings. Those with micral positive and MPS positive had multivessel CAD by CAG. It was seen that MPS status was 91.4% sensitive, 74.1% specific and had 82.1% positive predictive values (PPV) and 87.0% negative predictive value (NPV) for detection of significant CAD. CONCLUSION: Microalbuminuria is an inexpensive screening tool and a powerful independent predictor for major cardiovascular events in patients with type 2 diabetes mellitus. MPS is a sensitive, non invasive diagnostic test for identification of CAD in asymptomatic diabetic patients.

Potential role of FDG PET imaging in predicting metastatic potential and assessment of therapeutic response to neoadjuvant chemotherapy in Ewing sarcoma family of tumors.

AIMS AND OBJECTIVES: The aim of this study was to retrospectively correlate FDG uptake in primary Ewing sarcoma family of tumors (ESFT) with tumor behavior, and to evaluate whether FDG PET can be used to predict response to neoadjuvant chemotherapy (NACT) in this patient group. METHODS: Out of the total 54 patients of recently diagnosed ESFT who underwent pretreatment FDG PET imaging, group I included patients without metastasis at presentation (n = 34) and group II included those with metastasis at presentation (n = 20). Fourteen of these patients had undergone FDG PET after 4 cycles of induction chemotherapy and surgical resection of primary tumor. In this subgroup of 14 patients, maximum standardized uptake value (SUVmax) of primary tumor was estimated before and after 4 cycles of induction chemotherapy and was correlated with the histopathological response in terms of necrosis in the tumor specimen. RESULTS: Mean SUVmax in the primary tumor in group I patients was 6.84 and in group II patients, it was 11.31. The difference between mean SUVmax of these 2 groups was significant by Wilcoxon test analysis, with P < 0.01. In group II patients, SUVmax in metastasis with maximum FDG uptake was consistently lower as compared with that of primary tumor. In subgroup of 14 patients, Pearson correlation analysis showed that percentage change in SUVmax of primary tumor correlated well with percentage necrosis on histopathological examination (P < 0.01). CONCLUSION: FDG uptake in primary ESFT reflected its metastatic potential and hence the aggressive behavior. The significant correlation between change in metabolic activity of the primary tumor and histopathological response after neoadjuvant chemotherapy suggests that FDG PET may be an ideal noninvasive method to assess tumor behavior and response to therapy in ESFT.

Hot tongue on FDG PET scan in a patient of Hodgkin's lymphoma undergoing antipsychotic treatment.

Fluorine-18 fluorodeoxyglucose positron emission tomography-computed tomography (F-18 FDG PET-CT) is the modality of choice for the diagnosis, staging, and restaging of many malignancies. The importance of eliminating false positives cannot be underestimated because they can dramatically alter the clinical course. We present a case of benign uptake in the tongue secondary to tardive dyskinesia in a 53-year-old woman referred for therapy response evaluation of Hodgkin's lymphoma who was concurrently receiving oral antipsychotic therapy. This case emphasizes the importance of detailed clinical history and examination when concluding definite diagnosis.