FDG PET-CT combined with TBNA for the diagnosis of atypical relapsing polychondritis: report of 2 cases and a literature review

Objective

To explore the value of ¹⁸F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) combined with transbronchial needle aspiration (TBNA) in diagnosing atypical relapsing polychondritis (RP).

Methods

Data from two patients with atypical RP, which had been diagnosed in our hospital using FDG PET-CT combined with TBNA, were retrospectively analyzed. A review of the relevant literature was also performed.

Results

Consistent with the previously reported 20 cases of RP that had been diagnosed using FDG PET-CT, the two patients in the present study showed the involvement of multiple organs, including the nose, throat, trachea, bronchi, costicartilage and joint cartilages, and increased FDG uptake was found in these areas. The mean value of SUVmax was 5.14. PET-CT revealed that 86.4% of the patients with RP had airway involvement. TBNA technique was used for biopsy of the hypermetabolic lesions, and pathologic examinations confirmed the diagnosis of RP. The time to diagnosis in these two patients and the 20 cases reported previously was about 6.9 months, significantly shorter than the average diagnosis time (20 months).

Conclusions

FDG PET-CT has several advantages for diagnosing RP, especially atypical RP. TBNA is a minimally invasive and safe technique for obtaining airway cartilage. Combining PET-CT with TBNA may play an important role in shortening the time to diagnosis in patients with RP involvement of airway.     

Occupant Dynamics in Rollover Crashes: Influence of Roof Deformation and Seat Belt Performance on Probable Spinal Column Injury

Motor vehicle crashes are the leading cause of death in the United States for people ages 3-33, and rollover crashes have a higher fatality rate than any other crash mode. At the request and under the sponsorship of Ford Motor Company, Autoliv conducted a series of dynamic rollover tests on Ford Explorer sport utility vehicles (SUV) during 1998 and 1999. Data from those tests were made available to the public and were analyzed in this study to investigate the magnitude of and the temporal relationship between roof deformation, lap-shoulder seat belt loads, and restrained anthropometric test dummy (ATD) neck loads. During each of the three FMVSS 208 dolly rollover tests of Ford Explorer SUVs, the far-side, passenger ATDs exhibited peak neck compression and flexion loads, which indicated a probable spinal column injury in all three tests. In those same tests, the near-side, driver ATD neck loads never predicted a potential injury. In all three tests, objective roof/pillar deformation occurred prior to the occurrence of peak neck loads (F ( z ), M ( y )) for far-side, passenger ATDs, and peak neck loads were predictive of probable spinal column injury. The production lap and shoulder seat belts in the SUVs, which restrained both driver and passenger ATDs, consistently allowed ATD head contact with the roof while the roof was contacting the ground during this 1000 ms test series. Local peak neck forces and moments were noted each time the far-side, passenger ATD head contacted ("dived into") the roof while the roof was in contact with the ground; however, the magnitude of these local peaks was only 2-13% of peak neck loads in all three tests. "Diving-type" neck loads were not predictive of injury for either driver or passenger ATD in any of the three tests.     

2-Deoxy-2-[F-18]fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose-Positron Emission Tomography Sensitivity to Serum Glucose: A Survey and Diagnostic Applications

OBJECTIVE: The positron emission tomography (PET) clinical utility of the sensitivity (gamma) of uptake (Q) to a change in plasma glucose concentration (C) is investigated. METHODS: Gamma is obtained from data as [ln(Q (2)/Q (1))] / [ln(C(2)/C(1))], using previously published intrapatient studies varying C within a single patient and some interpatient ones. It can be theoretically related to the half-saturation constant in the Michaelis-Menten quantification of competitive uptake. One of its uses is making uptake corrections for desired vs. actual C using Q(2) = Q(1) (C(2)/C(1))(gamma). RESULTS: Intrapatient studies proved to be preferable to interpatient ones, and a 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET survey with analyses for gamma yielded the following result: usually the gamma values of tumors and brain tissues were near -1, whereas those of other noncerebral tissues were near 0. Regarding correcting uptakes for C, instead of a universally assumed and applied gamma = -1, corrections should be for a single tissue using its known gamma. An advantageous use of gamma is predicting how C affects image contrast, including where glucose loading is sometimes preferable to fasting. CONCLUSIONS: A potentially useful quantifier of uptake sensitivity to plasma glucose has been defined and values obtained. Correcting uptakes to some standard C requires special care. gamma can help PET clinicians select fasting or loading to achieve glucose levels for optimum contrast.     

Using positron emission tomography to study human ketone body metabolism: A review

Ketone bodies – 3-hydroxybutyrate and acetoacetate – are important fuel substrates, which can be oxidized by most tissues in the body. They are synthesized in the liver and are derived from fatty acids released from adipose tissue. Intriguingly, under conditions of stress such as fasting, arterio-venous catheterization studies have shown that the brain switches from the use of almost 100% glucose to the use of > 50–60% ketone bodies. A similar adaptive mechanism is observed in the heart, where fasting induces a shift toward ketone body uptake that provides the myocardium with an alternate fuel source and also favorably affects myocardial contractility. Within the past years there has been a renewed interest in ketone bodies and the possible beneficial effects of fasting/semi-fasting/exercising and other “ketogenic” regimens have received much attention. In this perspective, it is promising that positron emission tomography (PET) techniques with isotopically labeled ketone bodies, fatty acids and glucose offer an opportunity to study interactions between ketone body, fatty acid and glucose metabolism in tissues such as the brain and heart. PET scans are non-invasive and thus eliminates the need to place catheters in vascular territories not easily accessible. The short half-life of e.g. 11C-labeled PET tracers even allows multiple scans on the same study day and reduces the total radiation burden associated with the procedure. This short review aims to give an overview of current knowledge on ketone body metabolism obtained by PET studies and discusses the methodological challenges and perspectives involved in PET ketone body research.     

Choroid Plexus as the Best Reference Region for Standardized Uptake Value Analysis on C11-Acetate PET/CT for Grading and Predicting Prognosis in Patients with Cerebral Gliomas

PurposeWe aimed to compare different reference regions and select one with the most clinical relevance on C11-acetate (ACE) positron emission tomography/computed tomography (PET/CT) in patients with cerebral glioma.MethodsWe retrospectively reviewed 51 patients with cerebral glioma who underwent baseline ACE PET/CT at diagnosis. Other than the standardized uptake value (SUV) of the primary tumor, SUVs of the reference regions including the normal gray matter, white matter, choroid plexus, and cerebellum were measured. Then, the SUV ratio (SUV_R = tumor SUV_max/reference region SUV_mean) was calculated. The effect of patient age on the SUV_mean of each reference was examined and the SUV_Rs of each reference region were compared between grades. age, sex, tumor size, histological grades, SUV_R, and the presence of isocitrate dehydrogenase (IDH) mutation were included for survival analyses.ResultsExcept for the cerebellum showing a mild negative correlation, we found no correlations between age and SUV_mean using the gray matter, white matter, and choroid plexus (r = − 0.280, P = 0.047). Only the SUV_R-choroid plexus was able to differentiate between the WHO grades (Grade II vs. III, P = 0.035; grade III vs. IV, P < 0.001; grade II vs. IV, P < 0.001). Multivariate Cox proportional hazards models found that the SUVR-choroid plexus and IDH mutation were statistically significant for predicting OS.ConclusionOf the different reference regions used for grading cerebral gliomas, the choroid plexus was found to be the most optimal. In addition, the SUV ratio is useful to predict the overall survival in the model with the choroid plexus as a reference region.     

Chemotherapy response evaluation with FDG-PET in patients with colorectal cancer.

BACKGROUND: The aim of this prospective study was to evaluate the value of F-18-fluorodeoxyglucose-positron emission tomography (FDG-PET) for early assessment of chemotherapy response in patients with advanced colorectal cancer. METHODS: Dynamic FDG-PET was carried out before and at 2 (n = 50) and 6 months (n = 19) after the start of treatment. Quantitative Patlak analysis [metabolic rate of glucose (MRGlu)] and a simplified method to measure glucose metabolism [standardized uptake value (SUV)] were evaluated. The predictive value of changes in glucose metabolism was assessed with Cox proportional regression analysis. Overall survival (OS) and progression-free survival (PFS) were calculated using Kaplan-Meier estimates. RESULTS: There was an increase in the rates of death (P = 0.049 for DeltaMRGlu PET1-2; P = 0.017 for DeltaSUV PET1-2; P = 0.032 for DeltaMRGlu PET1-3; P = 0.048 for DeltaSUV PET1-3) and progression (P = 0.026 for DeltaMRGlu PET1-2; P = 0.035 for DeltaSUV PET1-2; P = 0.041 for DeltaMRGlu PET1-3; P = 0.081 for DeltaSUV PET1-3) associated with worse response as assessed by PET on Cox proportional regression analysis. The OS and PFS analysis showed a significant predictive value at broad ranges of DeltaMRGlu and DeltaSUV cut-off levels. CONCLUSION: The degree of chemotherapy-induced changes in tumor glucose metabolism is highly predictive for patient outcome. The use of FDG-PET for therapy monitoring seems clinically feasible since simplified methods (SUV) are sufficiently reliable.     

Use of a standardized uptake value for parametric in vivo imaging of benzodiazepine receptor distribution on [<Superscript>11</Superscript>C]flumazenil brain PET

To simplify the acquisition protocol of carbon-11 labeled flumazenil (FMZ) positron emission tomography (PET) for distribution volume (DV) images, we attempted to obtain standardized uptake value (SUV) images compatible with DV images, and assessed the applicability of this method in patients with unilateral cerebrovascular diseases (CVD). [¹¹C]FMZ PET was performed in ten normal subjects. A DV image and ten sequential 5-min SUV images were generated for each subject. We investigated the correlation coefficient (r) and standard estimation of error (SEE) between the latter ten static images and the DV image using the pixel-by-pixel method, thereby determining the optimum acquisition phase. The same FMZ PET procedure was performed in 15 patients with unilateral CVD. Twenty regions of interest (ROIs) were positioned both in lesioned areas and in symmetrical regions. DV and SUV in the optimum phase for each ROI were calculated to compare the lesion-to-normal (L/N) ratio of DV and that of SUV. The highest r and a low SEE (r=0.957, SEE=633) were observed from 30 to 35 min after tracer administration in the study of normal subjects. A high r (0.945) and a low SEE (0.0438) between the DV L/N ratio and the SUV L/N ratio were obtained in the study of patients. Our study suggests that SUV images acquired from 30 to 35 min after FMZ administration are a suitable alternative to DV images not only in normal subjects but also in patients with unilateral CVD. This simple method seems to be valuable for the identification of altered neuronal activity in patients with CVD.