Impact of blood glucose, diabetes, insulin, and obesity on standardized uptake values in tumors and healthy organs on 18F-FDG PET/CT

INTRODUCTION

Chronically altered glucose metabolism interferes with (18)F-FDG uptake in malignant tissue and healthy organs and may therefore lower tumor detection in (18)F-FDG PET/CT. The present study assesses the impact of elevated blood glucose levels (BGL), diabetes, insulin treatment, and obesity on (18)F-FDG uptake in tumors and biodistribution in normal organ tissues.

METHODS

(18)F-FDG PET/CT was analyzed in 90 patients with BGL ranging from 50 to 372 mg/dl. Of those, 29 patients were diabetic and 21 patients had received insulin prior to PET/CT; 28 patients were obese with a body mass index >25. The maximum standardized uptake value (SUV(max)) of normal organs and the main tumor site was measured. Differences in SUV(max) in patients with and without elevated BGLs, diabetes, insulin treatment, and obesity were compared and analyzed for statistical significance.

RESULTS

Increased BGLs were associated with decreased cerebral FDG uptake and increased uptake in skeletal muscle. Diabetes and insulin diminished this effect, whereas obesity slightly enhanced the outcome. Diabetes and insulin also increased the average SUV(max) in muscle cells and fat, whereas the mean cerebral SUV(max) was reduced. Obesity decreased tracer uptake in several healthy organs by up to 30%. Tumoral uptake was not significantly influenced by BGL, diabetes, insulin, or obesity.

CONCLUSIONS

Changes in BGLs, diabetes, insulin, and obesity affect the FDG biodistribution in muscular tissue and the brain. Although tumoral uptake is not significantly impaired, these findings may influence the tumor detection rate and are therefore essential for diagnosis and follow-up of malignant diseases.

Superior diagnostic performance of perfusion-cardiovascular magnetic resonance versus SPECT to detect coronary artery disease: The secondary endpoints of the multicenter multivendor MR-IMPACT II (Magnetic Resonance Imaging for Myocardial Perfusion Assessment in Coronary Artery Disease Trial)

BACKGROUND

Perfusion-cardiovascular magnetic resonance (CMR) is generally accepted as an alternative to SPECT to assess myocardial ischemia non-invasively. However its performance vs gated-SPECT and in sub-populations is not fully established. The goal was to compare in a multicenter setting the diagnostic performance of perfusion-CMR and gated-SPECT for the detection of CAD in various populations using conventional x-ray coronary angiography (CXA) as the standard of reference.

METHODS

In 33 centers (in US and Europe) 533 patients, eligible for CXA or SPECT, were enrolled in this multivendor trial. SPECT and CXA were performed within 4 weeks before or after CMR in all patients. Prevalence of CAD in the sample was 49% and 515 patients received MR contrast medium. Drop-out rates for CMR and SPECT were 5.6% and 3.7%, respectively (ns). The study was powered for the primary endpoint of non-inferiority of CMR vs SPECT for both, sensitivity and specificity for the detection of CAD (using a single-threshold reading), the results for the primary endpoint were reported elsewhere. In this article secondary endpoints are presented, i.e. the diagnostic performance of CMR versus SPECT in subpopulations such as multi-vessel disease (MVD), in men, in women, and in patients without prior myocardial infarction (MI). For diagnostic performance assessment the area under the receiver-operator-characteristics-curve (AUC) was calculated. Readers were blinded versus clinical data, CXA, and imaging results.

RESULTS

The diagnostic performance (= area under ROC = AUC) of CMR was superior to SPECT (p = 0.0004, n = 425) and to gated-SPECT (p = 0.018, n = 253). CMR performed better than SPECT in MVD (p = 0.003 vs all SPECT, p = 0.04 vs gated-SPECT), in men (p = 0.004, n = 313) and in women (p = 0.03, n = 112) as well as in the non-infarct patients (p = 0.005, n = 186 in 1-3 vessel disease and p = 0.015, n = 140 in MVD).

CONCLUSION

In this large multicenter, multivendor study the diagnostic performance of perfusion-CMR to detect CAD was superior to perfusion SPECT in the entire population and in sub-groups. Perfusion-CMR can be recommended as an alternative for SPECT imaging.

TRIAL REGISTRATION

ClinicalTrials.gov, Identifier: NCT00977093.

[Image-guided radiation therapy. Paradigm change in radiation therapy]

CLINICAL ISSUE

The introduction of image-guided radiotherapy (IGRT) has changed the workflow in radiation oncology more dramatically than any other innovation in the last decades.

STANDARD TREATMENT

Imaging for treatment planning before the initiation of the radiotherapy series does not take alterations in patient anatomy and organ movement into account.

TREATMENT INNOVATIONS

The principle of IGRT is the temporal and spatial connection of imaging in the treatment position immediately before radiation treatment.

DIAGNOSTIC ASSESSMENT

The actual position and the target position are compared using cone-beam computed tomography (CT) or stereotactic ultrasound.

PERFORMANCE

The IGRT procedure allows a reduction of the safety margins and dose to normal tissue without an increase in risk of local recurrence.

ACHIEVEMENTS

In the future the linear treatment chain in radiation oncology will be developed based on the closed-loop feedback principle.

PRACTICAL RECOMMENDATIONS

The IGRT procedure is increasingly being used especially for high precision radiotherapy, e.g. for prostate or brain tumors.

MR-IMPACT II: Magnetic Resonance Imaging for Myocardial Perfusion Assessment in Coronary artery disease Trial: perfusion-cardiac magnetic resonance vs. single-photon emission computed tomography for the detection of coronary artery disease: a comparative multicentre, multivendor trial

AIMS

Perfusion-cardiac magnetic resonance (CMR) has emerged as a potential alternative to single-photon emission computed tomography (SPECT) to assess myocardial ischaemia non-invasively. The goal was to compare the diagnostic performance of perfusion-CMR and SPECT for the detection of coronary artery disease (CAD) using conventional X-ray coronary angiography (CXA) as the reference standard.

METHODS AND RESULTS

In this multivendor trial, 533 patients, eligible for CXA or SPECT, were enrolled in 33 centres (USA and Europe) with 515 patients receiving MR contrast medium. Single-photon emission computed tomography and CXA were performed within 4 weeks before or after CMR in all patients. The prevalence of CAD in the sample was 49%. Drop-out rates for CMR and SPECT were 5.6 and 3.7%, respectively (P = 0.21). The primary endpoint was non-inferiority of CMR vs. SPECT for both sensitivity and specificity for the detection of CAD. Readers were blinded vs. clinical data, CXA, and imaging results. As a secondary endpoint, the safety profile of the CMR examination was evaluated. For CMR and SPECT, the sensitivity scores were 0.67 and 0.59, respectively, with the lower confidence level for the difference of +0.02, indicating superiority of CMR over SPECT. The specificity scores for CMR and SPECT were 0.61 and 0.72, respectively (lower confidence level for the difference: -0.17), indicating inferiority of CMR vs. SPECT. No severe adverse events occurred in the 515 patients.

CONCLUSION

In this large multicentre, multivendor study, the sensitivity of perfusion-CMR to detect CAD was superior to SPECT, while its specificity was inferior to SPECT. Cardiac magnetic resonance is a safe alternative to SPECT to detect perfusion deficits in CAD.

[Shoulder injuries in overhead athletes: utility of MR arthrography]

INTRODUCTION

The goal of this work was to assess the accuracy of the MR-Arthrografie in the evaluation of over head athletes injuries in comparison with athroscopy.

MATERIAL AND METHODS

In 29 patients (middle age: 30 years, 21 male, 8 female, age 16 - 53 years) with persistent pain after conservative therapy an Arthro-MRI with intraarticular application of gadolinum was performed prior to arthroscopic surgery. The MRI was retrospectivly analysed of three examiners independently from one another. The result were compared to the results of the Arthroscopy. Interrater Reliability was calculated by using of Cohens Kappa.

RESULTS

The MR-Arthrography could demonstrate 8 of 9 (88.9 %) partial tears of he rotator cuff. All SLAP (Superiores Labrum from Anterior to Posterior) Lesions as well as all bankart type Lesions were recognized through the MR-Arthrography. However, dependent upon the experience of the examiner in a span between 33.3 % (fellow radiologist) and 93.3 % (consultant radiologist). We found a high agreement between consultant radiologist and shoulder surgeon with Kappa of 0.79 for rotator cuff tear-, 0.86 for Bankart- and 0.82 for SLAP-Läsionen.

Myocardial First Pass Perfusion Imaging With Gadobutrol

OBJECTIVE

To implement parallel imaging algorithms in fast gradient recalled echo sequences for myocardial perfusion imaging and evaluate image quality, signal-to-noise ratio (SNR), contrast-enhancement ratio (CER), and semiquantitative perfusion parameters.

MATERIALS AND METHODS

In 20 volunteers, myocardial perfusion imaging with gadobutrol was performed at rest using an accelerated TurboFLASH sequence (TR 2.3 milliseconds, TE 0.93 milliseconds, flip angle [FA] 15 degrees) with GRAPPA, R=2. A nonaccelerated TurboFLASH sequence with similar scan parameters served as standard of reference. Artifacts were assessed qualitatively. SNR, CER, and CNR were calculated and semiquantitative perfusion parameters were determined from fitted SI-time curves.

RESULTS

Phantom measurements yielded significant higher SNR for nonaccelerated images (P<0.001). CER was equal; differences in CNR were statistically nonsignificant. The evaluation of semiquantitative perfusion parameters yielded significantly higher peak signal intensities in nonaccelerated images (P<0.001). Differences in maximum upslope were statistically nonsignificant. A qualitative examination of all images for artifacts by 2 board-certified radiologists yielded a significant reduction in dark rim artifacts with GRAPPA, R=2 (P<0.001).

CONCLUSIONS

The application of GRAPPA with an acceleration factor of R=2 leads to a significant reduction of dark rim artifacts in fast gradient recalled echo sequences.

Myocardial Perfusion Imaging With Gadobutrol: A Comparison Between 3 and 1.5 Tesla With an Identical Sequence Design

OBJECTIVES

To implement myocardial first-pass perfusion imaging at 3 Tesla and to evaluate the potential benefit with regard to signal parameters in comparison to 1.5 Tesla using identical sequence settings and an intraindividual comparison.

MATERIALS AND METHODS

In 16 volunteers, myocardial first-pass perfusion imaging was performed at 1.5 Tesla (Magnetom Avanto) and 3 Tesla (Magnetom TIM Trio) after injection of 0.05 mmol/kg body weight Gadobutrol using an accelerated saturation recovery TurboFLASH technique (GRAPPA; R=2) at 1.5 and 3 Tesla. Detailed sequence parameters (TR 2.3 milliseconds, TE 0.93 milliseconds, flip angle 15 degrees , bandwidth 780 Hz/px) as well as spatial resolution were kept identical for both field strengths. Artifacts were assessed quantitatively and qualitatively, signal-to-noise ratio (SNR) and contrast enhancement ratio (CER) were calculated from raw data signal intensity-time curves. A linear fit on the upslope was performed for semiquantitative perfusion analysis.

RESULTS

SNR was significantly higher at 3 Tesla than at 1.5 Tesla (35.7+/-11.9 vs. 18.0+/-5.5, P<0.001). CER was significantly greater at 3 Tesla than at 1.5 Tesla (2.2+/-0.9 vs. 1.4+/-0.5, P<0.001). Maximum upslope was significantly higher at 3 Tesla than at 1.5 Tesla (3.3+/-2.4 vs. 2.0+/-1.0, P<0.001). A qualitative examination of all images for artifacts by 2 board-certified radiologists yielded no significant differences between the field strengths.

CONCLUSIONS

Three Tesla significantly improves CER and SNR compared with 1.5 Tesla with identical sequence parameters. In addition, the most important semiquantitative perfusion parameter maximum upslope is significantly increased. This may allow for an improvement of spatial resolution and potentially for a better delineation of perfusion defects. However, further studies are necessary to potentially demonstrate a benefit of 3 Tesla perfusion imaging in a clinical setting.