Applications of fluorodeoxyglucose-PET imaging in the detection of infection and inflammation and other benign disorders

FDG PET/CT in Hantavirus Hemorrhagic Fever With Renal Syndrome

ABSTRACT

A 58-year-old man with fever, myalgia, and dysuria was admitted to the hospital. Because of prolonged fever, FDG PET/CT was performed. Surprisingly, bilateral kidneys were rapidly enlarged for 5 days with the renal parenchyma showing intense hypermetabolism. FDG PET/CT demonstrated physiology of Hantavirus invading kidneys and causing nephritis. This case illustrates that FDG PET/CT could be the choice of image modality for diagnosis and treatment evaluation of patients suspected of hemorrhagic fever with renal syndrome. To the best of our knowledge, this is the first report of FDG PET/CT image for a patient with hemorrhagic fever with renal syndrome.

New Onset of Tuberculosis Complicating FDG PET/CT Evaluation in Patient With Recent Chimeric Antigen Receptor T-Cell Therapy

ABSTRACT

A 16-year-old adolescent girl with CD19 chimeric antigen receptor (CAR) T-cell therapy for acute lymphoblastic leukemia experienced new onset of the fever. 18 F-FDG PET/CT studies acquired at 1 and 2 months, respectively, after CAR-T, showed foci of abnormal activity in the mediastinal lymph nodes not seen on the study before therapy. However, these foci of abnormal activity were later proven due to newly developed tuberculosis after CAR T-cell therapy.

Investigating the attenuating effect of telmisartan against radiation-induced intestinal injury using 18F-FDG micro-PET imaging

BACKGROUND AND OBJECTIVE

This study was aimed to investigate the ability of ¹⁸F-Fluro-deoxy-glucose (¹⁸F-FDG)-based micro-positron emission tomography (microPET) imaging to evaluate the efficacy of telmisartan, a highly selective angiotensin II receptor antagonist (ARA), in intestinal tissue recovery process after in vivo irradiation.

METHODS

Male Balb/c mice were randomly divided into four groups of control, telmisartan, irradiation, and telmisartan + irradiation. A solution of telmisartan in phosphate-buffered saline (PBS) was administered orally at 12 mg/kg body weight for seven consecutive days prior to whole body exposing to a single sub-lethal dose of 5 Gy X-rays. The mice were imaged using ¹⁸F-FDG microPET at 9 and 30 days post-irradiation. The ¹⁸F-FDG uptake in jejunum was determined according to the mean standardized uptake value (SUVmean) index. Tissues were also processed in similar time points for histological analysis.

RESULTS

The ¹⁸F-FDG microPET imaging confirmed the efficacy of telmisartan as a potent attenuating agent for ionizing radiation-induced injury of intestine in mice model. The results were also in line with the histological analysis indicating that pretreatment with telmisartan reduced damage to the villi, crypts, and intestinal mucosa compared with irradiated and non-treated group from day 9 to 30 after irradiation.

CONCLUSION

The results revealed that ¹⁸F-FDG microPET imaging could be a good candidate to replace time-consuming and invasive biological techniques for screening of radioprotective agents. These findings were also confirmed by histological examinations which indicated that telmisartan can effectively attenuates radiation injury caused by ionizing-irradiation.

FDG PET/CT in 3 Cases of Hypertrophic Pachymeningitis Associated With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis

ABSTRACT

Hypertrophic pachymeningitis associated with antineutrophil cytoplasmic antibody-associated vasculitis is a rare dural inflammatory disorder. We describe MRI and FDG PET/CT findings in 3 cases of hypertrophic pachymeningitis associated with antineutrophil cytoplasmic antibody-associated vasculitis. Enhanced brain MRI of the 3 cases showed linear enhancement of the thickened dura matter involving the skull base, tentorium, and/or convexity. On FDG PET/CT, the thickened dura matter showed diffusely increased FDG uptake with SUVmax ranging from 5.8 to 11.3. Familiarity with these MRI and FDG PET/CT findings is helpful for correct diagnosis and treatment.

Splenic uptake on FDG PET/CT correlates with Kikuchi-Fujimoto disease severity

Kikuchi-Fujimoto disease (KFD) is usually self-limiting, but prolonged systemic symptoms often result in frequent hospital visits, long admission durations, or missed workdays. We investigated the role of fluorine-18 fluoro-2-deoxy-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in assessing KFD severity. We reviewed the records of 31 adult patients with pathologically confirmed KFD who underwent ¹⁸F-FDG PET/CT between November 2007 and April 2018 at a tertiary-care referral hospital. Disease severity was assessed using criteria based on clinical manifestations of advanced KFD. Systemic activated lymph nodes and severity of splenic activation were determined using semi-quantitative and volumetric PET/CT parameters. The median of the mean splenic standardized uptake value (SUV_mean) was higher in patients with severe KFD than those with mild KFD (2.38 ± 1.18 vs. 1.79 ± 0.99, p = 0.058). Patients with severe KFD had more systemically activated volume and glycolytic activity than those with mild KFD (total lesion glycolysis: 473.5 ± 504.4 vs. 201.6 ± 363.5, p = 0.024). Multivariate logistic regression showed that myalgia (odds ratio [OR] 0.035; 95% confidence interval [CI] 0.001–0.792; p = 0.035), total lymph node SUV_max (cutoff 9.27; OR 24.734; 95% CI 1.323–462.407; p = 0.032), and spleen SUV_mean (cutoff 1.79; OR 37.770; 95% CI 1.769–806.583; p = 0.020) were significantly associated with severe KFD. ¹⁸F-FDG PET/CT could be useful in assessing KFD severity.

Evaluation of the diagnostic efficacy of 18 F-Fluorine-2-Deoxy-D-Glucose PET/CT for lung cancer and pulmonary tuberculosis in a Tuberculosis-endemic Country

OBJECTIVE

To determine the diagnostic efficacy of ¹⁸ F-FDG PET/CT in distinguishing between pulmonary tuberculosis (PTB) and lung cancer in solitary pulmonary nodule (SPN) in a country with a high prevalence of PTB.

METHODS

Patients with SPN who underwent ¹⁸ F-FDG PET/CT imaging were retrospectively included in the study. The final diagnosis was established by histopathology. A linear regression equation was fitted to a scatter plot of size and SUVmax of lung cancer and PTB. ROC was used to determine the optimal cutoff values and diagnostic accuracy of ¹⁸ F-FDG PET/CT in PTB and lung cancer.

RESULTS

About 514 patients were included with the mean age of 57.5 ± 10.6 years. Four hundred and seventy-five cases were diagnosed as lung cancer, and 39 cases were PTB by histopathology. ¹⁸ F-FDG PET/CT had sensitivity, specificity, and diagnostic accuracy of 96.0%, 48.7%, and 92.0%, respectively. Utilization of SUVmax ≥2.5 in SPN resulted in 2 and 11 false positives cases of lung cancer and PTB, respectively, whereas SUVmax <2.5 resulted in 18 and 10 false-positive cases of lung cancer and PTB, respectively. The SUVmax and the size of short-axis in the lung cancer group were statistically higher than those in the PTB group. The linear regression equation parameters indicated the slope of the regression line of lung cancer was greater than that of PTB. The ROC curve demonstrated the SUVmax cutoff values of 4.85 and 2.25 for lung cancer and PTB, respectively for predicting the diagnostic accuracy of ¹⁸ F-FDG PET/CT.

CONCLUSION

¹⁸ F-FDG PET/CT has a higher sensitivity and diagnostic accuracy for malignant SPN. However, it has high false-positive rate and low specificity in tuberculosis endemic areas. Neither SUVmax nor the sizes of the nodules are valuable parameters for distinguishing between lung cancer and PTB. However, the SPN with larger short-axis and higher SUVmax would be inclined to malignant tumor.

Common features of F-18 FDG PET/CT findings in Scrub Typhus: prospective study before and after antibiotics therapy

Scrub typhus is an acute febrile illness caused by obligate intracellular organism Orientia tsutsugamushi. While there have been many reports on the evaluation of disease activity and infectious diseases using F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT), the clinical value of FDG PET/CT in scrub typhus has not been fully investigated. We enrolled 17 patients who were 18 years of age or older and clinically suspected of having scrub typhus with eschar. Clinical assessments, blood samples, and FDG PET/CT images were obtained at enrolment and again after 3 weeks. The median age of the patients was 65 years; 9 (52.9%) patients were male. On initial FDG PET/CT, the eschars showed markedly increased FDG uptake on PET imaging that improved after treatment. Generalized lymphadenopathy and splenomegaly with high FDG uptake were observed in all patients. On follow-up FDG PET/CT after appropriate therapy, FDG uptake and sizes of eschar, lymph nodes, and spleen were markedly decreased. As far as we are aware, this is the first investigation with multiple patients of FDG PET/CT in scrub typhus and the demonstration of clinical utility. FDG PET/CT imaging of scrub typhus could provide useful information about the clinical features before and after antibiotic treatment.

The utility of FDG-PET/CT imaging in the evaluation of multicentric reticulohistiocytosis: A case report

INTRODUCTION

Multicentric reticulohistiocytosis (MRH) is a rare histiocytic disorder that involves the skin, joints, and visceral organs.

CASE PRESENTATION

We report a 67-year-old woman with MRH who presented with a 2-years history of polyarthralgia and skin nodules. Her symptoms were an inflammatory polyarthropathy with punched-out lesions of the distal interphalangeal (DIP) joints of both hands. Doppler ultrasonography of the hands showed large bone erosions with power Doppler signals in the DIP joints. F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) demonstrated increased FDG uptake in cutaneous papules surrounding the affected joints, suggesting an inflammatory process. There was no evidence of malignancy. Biopsy samples of skin nodules exhibited dermal infiltration with CD68-positive histiocytes and multinucleated giant cells. The patient was diagnosed with MRH and treated with combination therapy comprising a steroid (prednisolone), tacrolimus, methotrexate, and infliximab, which resulted in clinical improvement. Following infliximab treatment, there was a significant decrease in a bone resorption marker (tartrate-resistant acid phosphatase 5b: TRACP-5b), suggesting that tumor necrosis factor-α targeting therapy may inhibit osteoclast formation and resorption activity in patients with MRH.

CONCLUSION

MRH is a progressive destructive arthritic condition, and early diagnostic and therapeutic strategies are necessary to improve the outcome. FDG-PET/CT and joint ultrasonography might be noninvasive imaging modalities that could help diagnose MRH.

18F-FDG PET/CT is an ideal imaging modality for the early diagnosis of relapsing polychondritis: A case report

BACKGROUND

Relapsing polychondritis (RP) is a rare autoimmune disease of unknown etiology that may affect multiple cartilage throughout the body.

CASE REPORT

We report on a middle-aged man presented with cough, chest tightness, and fever of unknown origin, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) was performed. And the imaging shows multiple increased FDG accumulation in tracheobronchial tree and all intercostal cartilages, as well as in nasal, right auricule, laryngeal cartilage. Based on the findings, the diagnosis of RP was made.

CONCLUSION

Our case demonstrates that FDG PET/CT is an useful diagnostic tool to accurately determine the extent of inflammation throughout the body and to guiding the selection of a biopsy site.

Acute radiation oesophagitis associated with 2-deoxy-2-[18F]fluoro-d-glucose uptake on positron emission tomography/CT during chemo-radiation therapy in patients with non-small-cell lung cancer

INTRODUCTION

Acute radiation oesophagitis (ARO) is frequently experienced by patients receiving concurrent chemo-radiation therapy (cCRT) for non-small-cell lung cancer (NSCLC). We investigated ARO symptoms (CTCAE v3.0), radiation dose and oesophageal FDG PET/CT uptake.

METHOD

Candidates received cCRT (60 Gy, 2 Gy/fx) and sequential FDG PET/CT (baseline FDG₀ , FDG_wk2 and FDG_wk4 ). Mean and maximum standardized uptake value (SUVmean and SUVmax) and radiation dose (O_mean and O_max ) were calculated within the whole oesophagus and seven sub-regions (5-60 Gy).

RESULTS

Forty-four patients underwent FDG₀ and FDG_wk2 , and 41 (93%) received FDG_wk4 , resulting in 129 PET/CT scans for analysis. Of 29 (66%) patients with ≥ grade 2 ARO, SUVmax (mean ± SD) increased from FDG₀ to FDG_wk4 (3.06 ± 0.69 to 3.83 ± 1.27, P = 0.0019) and FDG_wk2 to FDG_wk4 (3.10 ± 0.75 to 3.83 ± 1.27, P = 0.0046). Radiation dose (mean ± SD) was higher in grade ≥2 patients; O_mean (47.5 ± 20 vs 53.9 ± 10.2, P = 0.0061), O_max (13.7 ± 9.6 vs 20.1 ± 10.6, P = 0.0009) and V40 Gy (8.0 ± 8.2 vs 11.9 ± 7.3, P = 0.0185).

CONCLUSIONS

FDG_wk4 SUVmax and radiation dose were associated with ≥ grade 2 ARO. Compared to subjective assessments, future interim FDG PET/CT acquired for disease response assessment may also be utilized to objectively characterize ARO severity and image-guided oesophageal dose constraints.

Utility of PET/CT with fluorine-18-fluorodeoxyglucose-labeled autologous leukocytes for diagnosing diabetic foot osteomyelitis in patients with Charcot's neuroarthropathy

OBJECTIVE

Diabetic foot osteomyelitis (DFO) is difficult to diagnose in the presence of Charcot's neuroarthropathy (CN) and bone biopsy is not always possible. We aimed to assess the efficacy of PET/computed tomography using F-fluoride (F-fluoride PET/CT) and fluorine-18-fluorodeoxyglucose-labeled autologous leukocytes (F-FDG-LL PET/CT) in comparison with contrast-enhanced MRI (CEMRI) for the detection of DFO.

PATIENTS AND METHODS

Thirty-two patients with chronic CN and foot ulcer suspected of having DFO were prospectively evaluated. All patients underwent radiography, CEMRI, F-fluoride PET/CT, and F-FDG-LL PET/CT of the feet. Bone biopsy and microbiological culture from the suspected site of osteomyelitis was considered the gold standard.

RESULTS

Twenty-three patients fulfilled the inclusion criteria. Bone culture was suggestive of DFO in 12 patients. CEMRI identified 10 of the 12 cases of osteomyelitis. F-fluoride PET/CT and F-FDG-LL PET/CT showed increased tracer uptake (SUVmax=22.7±18.1 and 8.4±4.7, respectively) at the clinically involved site in 10 of the 12 patients (TP). Among 11 biopsy-negative patients, CEMRI reported DFO in four (false positive); there were no false positives with F-FDG-LL PET/CT. The sensitivity and specificity of F-FDG-LL PET/CT was 83.3 and 100% compared with 83.3 and 63.6% for CEMRI, respectively, for the diagnosis of DFO in the background of CN.

CONCLUSION

F-FDG-LL PET/CT has high specificity for the diagnosis of DFO in complicated diabetic foot. The F-fluoride PET/CT helps in the characterization the extent of underlying CN. An early and accurate diagnosis with F-FDG-LL PET/CT aids the rational initiation of antibiotics for DFO.

Optical imaging of bacterial infections

The rise in multidrug resistant (MDR) bacteria has become a global crisis. Rapid and accurate diagnosis of infection will facilitate antibiotic stewardship and preserve our ability to treat and cure patients from bacterial infection. Direct in situ imaging of bacteria offers the prospect of accurately diagnosing disease and monitoring patient outcomes and response to treatment in real-time. There have been many recent advances in the field of optical imaging of infection; namely in specific probe and fluorophore design. This combined with the advances in imaging device technology render direct optical imaging of infection a feasible approach for accurate diagnosis in the clinic. Despite this, there are currently no licensed molecular probes for clinical optical imaging of infection. Here we report some of the most promising and interesting probes and approaches under development for this purpose, which have been evaluated in in vivo models within the laboratory setting.

PET-CT for Evaluation of Spleen and Liver 18F-FDG Diffuse Uptake Without Lymph Node Enlargement in Lymphoma

The aim of the study was to compare differences between lymphoma and inflammation as indicated by high diffuse uptake of F-fluorodeoxyglucose (F-FDG) in the spleen, liver, and bone marrow without increased F-FDG uptake in the lymph nodes and without enlarged peripheral lymph nodes.Eighteen lymphoma patients and 14 inflammation patients were examined with F-FDG positron emission tomography-computer tomography (PET-CT). All patients displayed high diffuse uptake of F-FDG in the spleen, liver, and bone marrow without increased F-FDG uptake in the lymph nodes and without enlarged peripheral lymph nodes. Our analyses compared the maximum standardized uptake values (SUVmax) of F-FDG uptake ratios between the spleen/liver, the spleen/bone marrow, and the liver/bone marrow and further compared spleen sizes between lymphoma and inflammation patients.Using Student t test, no significant differences were found in the SUVmax ratios of spleen/liver and liver/bone marrow between the lymphoma and inflammation patients (t = 0.853, P = 0.401 > 0.05; t = 1.622, P = 0.115 > 0.05). However, the SUVmax ratio of the spleen/bone marrow of the lymphoma patients was significantly different from that of the inflammation patients (t = 2.426, P = 0.021 < 0.05). The spleen size between the lymphoma and inflammation patients was also significantly different (t = 2.911, P = 0.007 < 0.05).As indicated by F-FDG PET-CT, our study demonstrated that lymphoma and inflammation patients displayed a few differences despite both having high diffuse uptake of F-FDG in the spleen, liver, and bone marrow without enlarged peripheral lymph nodes and without increased F-FDG uptake in lymph nodes.

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging in response monitoring of extra-pulmonary tuberculosis

Positron emission tomography/computed tomography (PET/CT) using 2-deoxy-2-(fluorine-18) fluoro-D-glucose (¹⁸F-FDG) has become a standard diagnostic modality in oncological practice. F18-FDG PET/CT is sensitive in detecting malignancy; however, specificity is low in differentiating infections or inflammatory diseases from tumor. In the present case study, we report a patient with postoperative carcinoma of tongue presenting with cervical lymphadenopathy and fever. The PET/CT scan showed metabolically active generalized lymphadenopathy, and a possibility of lymphoma was suggested. Fine needle aspiration cytology showed the Ziehl–Neelsen staining to be strongly positive for acid-fast bacilli and first line of antitubercular drug was administrated. Six months later after the initiation of therapy, a follow-up PET/CT showed remarkable improvement of the disease status. This case study illustrates that tubercular infection can be a pitfall in F18-FDG PET/CT imaging. PET positive lesions do not always indicate malignancy, and histological confirmation of lesions with biopsy should always be performed. Once diagnosed to be tubercular, FDG PET/CT is a powerful imaging tool in monitoring the therapy.

Outcome after Discontinuing Long-Term Benzimidazole Treatment in 11 Patients with Non-resectable Alveolar Echinococcosis with Negative FDG-PET/CT and Anti-EmII/3-10 Serology

Background/Aims

Benzimidazoles are efficacious for treating non-resectable alveolar echinococcosis (AE), but their long-term parasitocidal (curative) effect is disputed. In this study, we prospectively analyzed the potential parasitocidal effect of benzimidazoles and whether normalization of FDG-PET/CT scans and anti-Emll/3-10-antibody levels could act as reliable "in vivo" parameters of AE-inactivation permitting to abrogate chemotherapy with a low risk for AE-recurrence.

Method

This prospective study included 34 patients with non-resectable AE subdivided into group A (n = 11), followed-up after diagnosis and begin of chemotherapy at months 6, 12 and 24, and group B (n = 23) with a medium duration of chemotherapy of 10 (range 2–25) years. All patients were assessed by FDG-PET/CT examinations and anti-EmII/3-10 serology. Chemotherapy was abrogated in patients with normalization of FDG-PET/CT and serum anti-EmII/3-10 levels. These patients were closely followed-up for AE recurrence. Endpoint (parasitocidal efficacy) was defined by the absence of AE-recurrence >24 months after stopping treatment.

Results

Normalization of FDG-PET/CT scan and anti-EmII/3-10 levels occurred in 11 of 34 patients (32%). After abrogation of chemotherapy in these 11 patients, there was no evidence of AE-recurrence within a median of 70.5 (range 16–82) months. However, the patients’ immunocompetence appears pivotal for the described long-term parasitocidal effect of benzimidazoles.

Conclusions

The combination of negative FDG-PET/CT-scans and anti-EmII/3-10 antibody levels seem to be reliable parameters for assessing in vivo AE-larval inactivity after long-term benzimidazole chemotherapy.

Trial Registration

clinicaltrials.gov: NCT00658294

Alveolar echinococcosis is one of the mostly deadly human parasitic diseases if left untreated. The treatment of choice is surgical resection, followed by two years of benzimidazole treatment. Unfortunately, only about 30–40% of patients have a resectable disease, while the others require medical treatment with benzimidazoles. As this therapy is only considered to be parasitostatic and as there are not yet reliable tools to assess parasite viability, the treatment usually is life-long. In this study, we evaluated FDG-PET/CT and antibody levels against the recombinant Emll/3-10 antigen as markers for parasite viability, allowing to select patients in whom chemotherapy could be stopped with low risk of AE-recurrence. Eleven 11 patients were identified with negative FDG-PET/CT-scans and anti-EmII/3-10 antibody levels in whom benzimidazole treatment was stopped with no evidence of AE-recurrence within a median follow-up of 70.5 (range 16–82) months. Therefore, this study provides evidence that benzimidazole treatment is parasitocidal in a subset of patients.

Localized Airspace Consolidation of Pulmonary Alveolar Proteinosis Mimicking Malignant Lesions in 18F-FDG PET/CT Imaging: One Case Report

Pulmonary alveolar proteinosis is a rare lung disease caused by diffuse, abnormal intra-alveolar surfactant accumulation. Here, we report a case of autoimmune pulmonary alveolar proteinosis with heterogeneous accumulation of F-FDG in both lungs shown on the combined F-FDG PET/CT.

Diffusion-weighted and PET/MR Imaging after Radiation Therapy for Malignant Head and Neck Tumors

Interpreting imaging studies of the irradiated neck constitutes a challenge because of radiation therapy-induced tissue alterations, the variable appearances of recurrent tumors, and functional and metabolic phenomena that mimic disease. Therefore, morphologic magnetic resonance (MR) imaging, diffusion-weighted (DW) imaging, positron emission tomography with computed tomography (PET/CT), and software fusion of PET and MR imaging data sets are increasingly used to facilitate diagnosis in clinical practice. Because MR imaging and PET often yield complementary information, PET/MR imaging holds promise to facilitate differentiation of tumor recurrence from radiation therapy-induced changes and complications. This review focuses on clinical applications of DW and PET/MR imaging in the irradiated neck and discusses the added value of multiparametric imaging to solve diagnostic dilemmas. Radiologists should understand key features of radiation therapy-induced tissue alterations and potential complications seen at DW and PET/MR imaging, including edema, fibrosis, scar tissue, soft-tissue necrosis, bone and cartilage necrosis, cranial nerve palsy, and radiation therapy-induced arteriosclerosis, brain necrosis, and thyroid disorders. DW and PET/MR imaging also play a complementary role in detection of residual and recurrent disease. Interpretation pitfalls due to technical, functional, and metabolic phenomena should be recognized and avoided. Familiarity with DW and PET/MR imaging features of expected findings, potential complications, and treatment failure after radiation therapy increases diagnostic confidence when interpreting images of the irradiated neck. Online supplemental material is available for this article.

Solitary subcutaneous gouty nodule mimicking metastatic melanoma on FDG PET/CT

A 68-year-old man with a history of malignant melanoma in the right axilla underwent FDG PET/CT. The images demonstrated a focally increased activity in the subcutaneous tissue anterior to the distal left tibia, suggestive of metastasis. However, a gouty tophus was diagnosed pathologically after biopsy.

Metabolic Pattern of Asymptomatic Hip-Prosthesis by 18F-FDG-Positron-Emission-Tomography

Background:

Joint replacement is a procedure with a major impact on the quality of life of patients with joint degenerative disease or traumatic injuries. However, some patients develop symptoms after the intervention caused by mechanical loosening or infection. Metabolic imaging by 18F-FDG-PET investigated in these patients isoften hampered by low specificity for diagnosis of possible septic vs. mechanical loosening. The reason for this shortcoming is to our opinion the unawareness of physiological remodeling processes that could be seen in asymptomatic patients.

Objectives:

In order to overcome this drawback, we aimed to find out the physiological metabolic functional pattern in asymptomatic patients with implanted hip prosthesis

Patients and Methods:

Twelve patients (6 males, 6 females); mean age 73 ± 7 (range 58 - 91) years were prospectively enrolled in the study. The patients were admitted to our department for oncological referral with implanted hip prostheses. All patients explained no symptoms with regard to their implanted prosthesis. The attenuation corrected images were used for analysis.

Results:

Fourteen hip prostheses in 12 patients were visually analyzed. Seven out of 14 prostheses among 12 patients showed focal periprosthetic enhanced metabolism, two of which showed two sites of enhanced uptake; whereas, the remaining five prostheses showed singular hypermetabolic areas within the periprosthetic site. The remaining seven prostheses in the other five patients showed no periprosthetic-enhanced uptake.

Conclusion:

Of the asymptomatic patients investigated, 58% showed focal enhanced periprosthetic glucose metabolism. This finding should be taken into consideration as a more probable unspecific metabolic pattern for correct interpretation of 18F-FDG-PET studies in patients with suspected septic loosening of the hip prosthesis.

Multimodal imaging of gliomas in the context of evolving cellular and molecular therapies

The vast majority of malignant gliomas relapse after surgery and standard radio-chemotherapy. Novel molecular and cellular therapies are thus being developed, targeting specific aspects of tumor growth. While histopathology remains the gold standard for tumor classification, neuroimaging has over the years taken a central role in the diagnosis and treatment follow up of brain tumors. It is used to detect and localize lesions, define the target area for biopsies, plan surgical and radiation interventions and assess tumor progression and treatment outcome. In recent years the application of novel drugs including anti-angiogenic agents that affect the tumor vasculature, has drastically modulated the outcome of brain tumor imaging. To properly evaluate the effects of emerging experimental therapies and successfully support treatment decisions, neuroimaging will have to evolve. Multi-modal imaging systems with existing and new contrast agents, molecular tracers, technological advances and advanced data analysis can all contribute to the establishment of disease relevant biomarkers that will improve disease management and patient care. In this review, we address the challenges of glioma imaging in the context of novel molecular and cellular therapies, and take a prospective look at emerging experimental and pre-clinical imaging techniques that bear the promise of meeting these challenges.

FDG-PET/CT pitfalls in oncological head and neck imaging

OBJECTIVES

Positron emission tomography-computed tomography (PET/CT) with fluorine-18-fluorodeoxy-D-glucose (FDG) has evolved from a research modality to an invaluable tool in head and neck cancer imaging. However, interpretation of FDG PET/CT studies may be difficult due to the inherently complex anatomical landmarks, certain physiological variants and unusual patterns of high FDG uptake in the head and neck. The purpose of this article is to provide a comprehensive approach to key imaging features and interpretation pitfalls of FDG-PET/CT of the head and neck and how to avoid them.

METHODS

We review the pathophysiological mechanisms leading to potentially false-positive and false-negative assessments, and we discuss the complementary use of high-resolution contrast-enhanced head and neck PET/CT (HR HN PET/CT) and additional cross-sectional imaging techniques, including ultrasound (US) and magnetic resonance imaging (MRI).

RESULTS

The commonly encountered false-positive PET/CT interpretation pitfalls are due to high FDG uptake by physiological causes, benign thyroid nodules, unilateral cranial nerve palsy and increased FDG uptake due to inflammation, recent chemoradiotherapy and surgery. False-negative findings are caused by lesion vicinity to structures with high glucose metabolism, obscuration of FDG uptake by dental hardware, inadequate PET scanner resolution and inherent low FDG-avidity of some tumours.

CONCLUSIONS

The interpreting physician must be aware of these unusual patterns of FDG uptake, as well as limitations of PET/CT as a modality, in order to avoid overdiagnosis of benign conditions as malignancy, as well as missing out on actual pathology.

TEACHING POINTS

• Knowledge of key imaging features of physiological and non-physiological FDG uptake is essential for the interpretation of head and neck PET/CT studies. • Precise anatomical evaluation and correlation with contrast-enhanced CT, US or MRI avoid PET/CT misinterpretation. • Awareness of unusual FDG uptake patterns avoids overdiagnosis of benign conditions as malignancy.

Intestinal pork tapeworm disease mimicking lymphoma on PET/CT imaging

A 17-year-old girl with abdominal pain for 3 months underwent 18F-FDG PET to evaluate possible malignancy due to unexplained ascites detected by ultrasound. The images demonstrated multiple foci of abnormally increased 18F-FDG activity in the lymphadenopathy from the neck to the abdomen and in the thickened intestinal wall. In addition, abnormal activity was noted in the pharynx and skeletons. Cysticercosis was confirmed pathologically.

The pivotal role of FDG-PET/CT in modern medicine

The technology behind positron emission tomography (PET) and the most widely used tracer, 2-deoxy-2-[18F]fluoro-D-glucose (FDG), were both conceived in the 1970s, but the latest decade has witnessed a rapid emergence of FDG-PET as an effective imaging technique. This is not least due to the emergence of hybrid scanners combining PET with computed tomography (PET/CT). Molecular imaging has enormous potential for advancing biological research and patient care, and FDG-PET/CT is currently the most widely used technology in this domain. In this review, we discuss contemporary applications of FDG-PET and FDG-PET/CT as well as novel developments in quantification and potential future indications including the emerging new modality PET/magnetic resonance imaging.

(18)F-FDG PET/CT in differentiating acute tuberculous from idiopathic pericarditis: preliminary study

PURPOSE

The aim of this study was to evaluate retrospectively the diagnostic capability of F-FDG PET/CT in differentiating acute tuberculous from idiopathic pericarditis.

METHODS

FDG PET/CT findings were reviewed in 15 patients with acute tuberculous (n = 5) or idiopathic pericarditis (n = 10). The maximal thickness and SUVmax of the pericardium and the number, size, and SUVmax of the mediastinal and supraclavicular lymph nodes with increased FDG uptake were measured.

RESULTS

All patients had small-to-large amount of pericardial effusion. The patients with acute tuberculous pericarditis (n = 5) showed diffuse (n = 3) or multifocal (n = 2) FDG uptake in the pericardia. The patients with acute idiopathic pericarditis (n = 10) showed diffuse (n = 6) or regional (n = 4) FDG uptake in the pericardia. The mean (SD) pericardial thickness and SUVmax of acute tuberculous pericarditis were significantly higher than those of acute idiopathic pericarditis (5.1 [1.0] vs 3.4 [0.9], P < 0.05; 13.5 [3.9] vs 3.0 [0.7], P < 0.05, respectively). A total of 69 mediastinal and supraclavicular lymph nodes with increased FDG uptake were observed in all 15 patients (44 in patients with acute tuberculous pericarditis and 25 in patients with acute idiopathic pericarditis). The mean (SD) SUVmax of mediastinal and supraclavicular lymph nodes of acute tuberculous pericarditis (5.3 [1.8]) was significantly higher than that of acute idiopathic pericarditis (2.8 [0.6], P < 0.05). There was no significant difference in the mean size of the mediastinal and supraclavicular lymph nodes between acute tuberculous and idiopathic pericarditis.

CONCLUSIONS

The degrees of FDG uptake in the pericardium and the mediastinal and supraclavicular lymph nodes are useful for differentiating acute tuberculous from idiopathic pericarditis. Familiarity with the FDG uptake patterns of acute tuberculous and idiopathic pericarditis may be helpful for successful (especially timely) diagnosis and treatment.

[Is it useful to perform additional colonoscopy to detect unmatched lesion between positron emission tomography/computed tomography and colonoscopy?]

BACKGROUND/AIMS

Incidentally detected focal 18F-fluorodeoxyglucose (FDG) uptake was compared with colonoscopy. We investigated the characteristics of colon adenomas which were revealed on PET/CT. Then we identified whether additional colonoscopy was necessary in patients with lesions which were revealed on PET/CT but had no matched lesions on colonoscopy.

METHODS

We retrospectively reviewed 95 patients who underwent colonoscopy within a 6 month interval after they had focal FDG uptake from January 2010 to May 2012 at National Police Hospital in Korea. Also, we analyzed 30 patients who underwent additional colonoscopy within 2 years after they had no matched lesions on primary colonoscopy.

RESULTS

PET/CT depicted 54.6% (41/75) of adenomas and adenocarcinomas. The PET visibility of colon adenoma was significantly associated with degree of dysplasia (p=0.027), histologic type (p=0.040), and the size (p=0.038). The positivity rate was increased with higher degree of dysplasia (low-grade dysplasia, 47%; high-grade dysplasia, 78%; adenocarcinoma, 100%) and villous patterns of histologic type (tubular, 46.8%; tubulovillous, 87.5%; villous, 100%). Patients with adenomas larger than 10 mm (87.5%) had higher detection rate compared to those with adenomas smaller than 10 mm (49.0%). Among the 30 patients who underwent additional colonoscopy, only one patient had a 6 mm sized tubular adenoma (low-grade dysplasia).

CONCLUSIONS

Incidental focal colonic uptake may indicate advanced adenoma or adenocarcinoma. Thus, it justifies performing colonoscopy for identifying the presence of colon neoplasms. However, in case of unmatched lesions between PET/CT and colonoscopy, there was little evidence that additional colonoscopy would yield benefits.

Colonoscopy and µPET/CT are valid techniques to monitor inflammation in the adoptive transfer colitis model in mice

BACKGROUND

Preclinical in vivo research on inflammatory bowel diseases requires proper animal models and techniques allowing longitudinal monitoring of colonic inflammation without the need to kill animals. We evaluated colonoscopy and μ-positron emission tomography/computed tomography (μPET/CT) as monitoring tools in a model for chronic colitis in mice.

METHODS

Colitis was induced by adoptive transfer of CD4(+)CD25(-)CD62L(+) T cells in immunocompromised severe combined immunodeficient mice. Three study protocols were designed. In study 1, colonoscopy and µPET/CT were performed once, 4 weeks after transfer. In study 2 and study 3, colitis was sequentially followed up through colonoscopy (study 2) or colonoscopy plus µPET/CT (study 3). Each study included postmortem evaluation of colonic inflammation (macroscopy, microscopy, and myeloperoxidase activity).

RESULTS

In study 1, both colonoscopy and µPET/CT detected colitis 4 weeks after transfer. Study 2 showed a gradual increase in colonoscopic score from week 2 (1.4 ± 0.6) to week 8 (6.0 ± 1.1). In study 3, colitis was detected 2 weeks after transfer by µPET/CT (2.0 ± 0.4) but not by colonoscopy, whereas both techniques detected inflammation 4 and 6 weeks after transfer. Colonoscopy correlated with µPET/CT (r = 0.812, 0.884, and 0.781, respectively) and with postmortem analyses in all 3 studies.

CONCLUSIONS

Adoptive transfer of CD4(+)CD25(-)CD62L(+) T cells in severe combined immunodeficient mice results in a moderate chronic colitis. Evolution of colitis could be monitored over time by both colonoscopy and µPET/CT. µPET/CT seems to detect inflammation at an earlier time point than colonoscopy. Both techniques represent reliable and safe methods without the need to kill animals.

Labelling of granulocytes by phagocytic engulfment with 64Cu-labelled chitosan-coated magnetic nanoparticles

PURPOSE

The aim of the present work was to perform the labelling of granulocytes by their engulfment with chitosan-coated magnetic (64)Cu nanoparticles (MNPs) in order to obtain a radiopharmaceutical suitable for dual imaging (PET-MRI) of inflammatory/infective diseases.

PROCEDURES

Specimens of 5-20 mg MNPs were washed with saline-isotonic solution and recuperated by magnetic decantation; 15-58 μg Cu(2+) (CuCl(2)·H(2)O) in 50 μl of acidified (pH 5.5) saline solution was added to the MNPs re-suspended saline-isotonic solution; 10 mg MNPs was allowed to react with 16 μg (64)Cu [(64)Ni(p,n) at 12-9 MeV] followed by anion exchange chromatography with a specific activity of 56 MBq/μg. Pellets of granulocytes were obtained from peripheral blood; MNPs engulfment by granulocytes was obtained and granulocyte-engulfed viability was assessed by the trypan blue exclusion (TBE) test performed at 5 min, 2 h and 4 h; assessment of the release of (64)Cu from labelled granulocytes in plasma was performed by measuring the radioactivity of both the cellular pellet and the supernatant solution.

RESULTS

Our data showed the binding capacity of chitosan-coated MNPs for cationic metal. The amount of Cu(+2) chelated captured per milligram of MNPs was constant and independent of the reagent concentrations. In all cases, more than 90% of the engulfed granulocytes were positive to the TBE test. The MNPs were localised within the cells.

CONCLUSION

In our in vitro model, MNPs are taken up by granulocytes through phagocytosis, whereas previously described methods were based on the use of a chelating agent that permit Cu to cross the cell membrane. Moreover, the (64)Cu-engulfed granulocytes showed a high stability of up to 80% of retained radioactivity after 24 h of incubation.

Specific biomarkers of receptors, pathways of inhibition and targeted therapies: clinical applications

A deeper understanding of the role of specific genes, proteins, pathways and networks in health and disease, coupled with the development of technologies to assay these molecules and pathways in patients, promises to revolutionise the practice of clinical medicine. In particular, the discovery and development of novel drugs targeted to disease-specific alterations could benefit significantly from non-invasive imaging techniques assessing the dynamics of specific disease-related parameters. Here we review the application of imaging biomarkers in the management of patients with brain tumours, especially malignant glioma. This first part of the review focuses on imaging biomarkers of general biochemical and physiological processes related to tumour growth such as energy, protein, DNA and membrane metabolism, vascular function, hypoxia and cell death. These imaging biomarkers are an integral part of current clinical practice in the management of primary brain tumours. The second article of the review discusses the use of imaging biomarkers of specific disease-related molecular genetic alterations such as apoptosis, angiogenesis, cell membrane receptors and signalling pathways. Current applications of these biomarkers are mostly confined to experimental small animal research to develop and validate these novel imaging strategies with future extrapolation in the clinical setting as the primary objective.

New treatments and imaging strategies in degenerative disease of the intervertebral disks

Magnetic resonance (MR) imaging in patients with persistent low back pain and sciatica effectively demonstrates spine anatomy and the relationship of nerve roots and intervertebral disks. Except in cases with nerve root compression, disk extrusion, or central stenosis, conventional anatomic MR images do not help distinguish effectively between painful and nonpainful degenerating disks. Hypoxia, inflammation, innervation, accelerated catabolism, and reduced water and glycosaminoglycan content characterize degenerated disks, the extent of which may distinguish nonpainful from painful ones. Applied to the spine, "functional" imaging techniques such as MR spectroscopy, T1ρ calculation, T2 relaxation time measurement, diffusion quantitative imaging, and radio nucleotide imaging provide measurements of some of these degenerative features. Novel minimally invasive therapies, with injected growth factors or genetic materials, target these processes in the disk and effectively reverse degeneration in controlled laboratory conditions. Functional imaging has applications in clinical trials to evaluate the efficacy of these therapies and eventually to select patients for treatment. This report summarizes the biochemical processes in disk degeneration, the application of advanced disk imaging techniques, and the novel biologic therapies that presently have the most clinical promise.