Incremental value of FDG-PET/CT to monitor treatment response in infectious spondylodiscitis.

OBJECTIVE: To assess the added value of serial 2-deoxy-2-[18F]fluoro-D-glucose (FDG) uptake analysis in predicting clinical response to treatment in infectious spondylodiscitis (IS). We sought to analyze changes in quantitative FDG-PET/CT parameters among patients with clinical response or treatment failure and to compare the sensitivity and specificity of serial FDG-PET/CT and MRI in predicting treatment response in IS. MATERIALS AND METHODS: This retrospective study consisted of 68 FDG-PET/CT examinations in 34 patients performed before and after at least 2 weeks of antibiotic treatment. Serial MRI scans were available in 32 (94%) patients before and after treatment. FDG-avid lesions were quantified as maximum standardized uptake value (SUVmax), partial-volume corrected lesion metabolic volume (LMV), and partial-volume corrected lesion metabolic activity (LMA). RESULTS: All FDG-PET/CT parameters significantly decreased in patients with clinical improvement (31/34, 91%, P < 0.001), while patients with disease progression did not show FDG-PET/CT improvement. FDG uptake decrease was similar between patients undergoing early assessment (< 6 weeks) compared with those performing FDG-PET/CT after 6 weeks of treatment. SUVmax, LMV, and LMA decrease over time was 39.0%, 97.4%, and 97.1%, respectively. In predicting clinical responses, SUVmax reduction > 15% and > 25% showed 94% and 89% sensitivity and 67% and 100% specificity compared with 37% and 50% of MRI, respectively. Low degree of agreement with clinical response was shown for MRI compared with FDG-PET/CT parameters using the Cohen kappa coefficient. CONCLUSIONS: FDG-PET/CT monitoring is a valuable tool to predict clinical response to treatment in IS and has greater sensitivity and specificity compared with MRI.

18F-Fluorodeoxyglucose positron emission tomography and infectious diseases: current applications and future perspectives.

PURPOSE OF REVIEW: 18F-Fluorodeoxyglucose positron emission tomography/computed tomography is a well-established technique for diagnosis and management of a number of neoplastic conditions. However, in recent years the body of literature regarding its potential role in infectious diseases has progressively increased, with promising results. RECENT FINDINGS: So far 18F-fluorodeoxyglucose positron emission tomography/computed tomography has a well-established role and is recommended by guidelines only in a few settings, such as prosthetic valve endocarditis, vascular device infections, and chronic osteomyelitis. However, even the lack of large, prospective randomized trials, an increasing number of small series and case reports suggest a potential role in the diagnosis, disease staging, and monitoring of treatment response of several other infective conditions. SUMMARY: In this article, we summarize the available evidence and potential future applications of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in the diagnosis and management of infectious diseases.

Successful treatment and FDG-PET/CT monitoring of HHV-6 encephalitis in a non-neutropenic patient: case report and literature review.

Human herpesvirus (HHV)-6 reactivation is associated with severe forms of encephalitis among patients undergoing hematopoietic stem cell transplantation. Cases in non-neutropenic patients are uncommon. The efficacy of ganciclovir and other compounds that are used for the treatment of HHV-6 encephalitis remains suboptimal and linked to toxicity. Valganciclovir, the oral prodrug of ganciclovir, could be practical to treat outpatients, but it is not commonly used for severe cases. We report a case of HHV-6 encephalitis in a non-neutropenic patient successfully treated with valganciclovir and undergoing therapeutic drug monitoring in plasma and in the cerebrospinal fluid. Resolution of infectious foci was documented by cerebral MRI and F18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). A review of the literature on HHV-6 encephalitis is also reported.

Higher fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) uptake in tuberculous compared to bacterial spondylodiscitis.

BACKGROUND: Tuberculous spondylodiscitis can be difficult to diagnose because of its nonspecific symptoms and the similarities with non-tubercular forms of spinal infection. Fluorine-18-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG PET-CT) is increasingly used for the diagnosis and monitoring of tubercular diseases. METHODS: Retrospective, case-control study comparing tuberculous spondylodiscitis with biopsy-confirmed pyogenic spondylodiscitis in the period 2010-2012. RESULTS: Ten cases of tuberculous spondylodiscitis and 20 controls were included. Compared to pyogenic, tuberculous spondylodiscitis was more frequent in younger patients (P = 0.01) and was more often associated with thoraco-lumbar tract lesions (P = 0.01) and multiple vertebral involvement (P = 0.01). Significantly higher maximum standardized uptake values (SUV) at FDG-PET were displayed by tuberculous spondylodiscitis compared to controls (12.4 vs. 7.3, P = 0.003). SUV levels above 8 showed the highest value of specificity (0.80). Mean SUV reduction of 48% was detected for tuberculous spondylodiscitis at 1-month follow-up. CONCLUSIONS: Higher SUV levels at FDG-PET were detected in tuberculous compared with pyogenic spondylodiscitis. PET-CT use appeared useful in the disease follow-up after treatment initiation.

Skeletal Muscle Metastases in HCC Revealed by 18F-Choline PET/CT.

ABSTRACT: We present a case of a 68-year-old woman undergoing 18F-choline PET/CT due to a history of hepatocellular cancer treated with multimodal therapies and with a rapid increase in α-fetoprotein. 18F-Choline PET/CT showed multiple uptakes in the skeletal muscles compatible with the recurrence of disease. The interpretation of 18F-choline PET/CT in this cancer should be careful and discussed in a multidisciplinary team.

Pleural Mesothelioma Detects by 18F-Choline PET/CT in a Patient With Biochemical Recurrence of Prostate Cancer.

A 73-year-old man with a prostate cancer treated by radical prostatectomy in 2006. For a biochemical recurrence of disease (prostate-specific antigen level, 0.1 ng/mL) during hormonal therapy, patient underwent F-choline PET/CT that showed a significant uptake in a diffuse right pleural thickening. The patient was sent to pleurectomy decortication showing an epithelioid pleural mesothelioma. This case highlighted that a histopathological evaluation is mandatory in case of a significant radiolabeled choline uptake in pleural lesions.