18F-FDG-PET/MRI in preoperative staging of oesophageal and gastroesophageal junctional cancer.

AIM: To evaluate integrated 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET)/magnetic resonance imaging (MRI), in comparison with the standard technique, integrated 18F-FDG-PET/computed tomography (CT), in preoperative staging of oesophageal or gastroesophageal junctional cancer. MATERIALS AND METHODS: In the preoperative staging of 16 patients with oesophageal or gastroesophageal junctional cancer, 18F-FDG-PET/MRI was performed immediately following the clinically indicated 18F-FDG-PET/CT. MRI-sequences included T1-weighted fat-water separation (Dixon's technique), T2-weighted, diffusion-weighted imaging (DWI), and gadolinium contrast-enhanced T1-weighted three-dimensional (3D) imaging. PET was performed with 18F-FDG. Two separate teams of radiologists conducted structured blinded readings of 18F-FDG-PET/MRI or 18F-FDG-PET/CT, which were then compared regarding tumour measurements and characteristics as well as assessment of inter-rater agreement (Cohen's kappa) for the clinical tumour, nodal and metastatic (TNM) stage. RESULTS: There were no medical complications. Comparison of tumour measurements revealed high correlations without significant differences between modalities. The maximum standardised uptake value (SUVmax) values of the primary tumour with 18F-FDG-PET/MRI had excellent correlation to those of 18F-FDG-PET/CT (0.912, Spearman's rho). Inter-rater agreement between the techniques regarding T-stage was only fair (Cohen's kappa, 0.333), arguably owing to relative over-classification of the T-stage using 18F-FDG-PET/CT. Agreements in the assessment of N- and M-stage were substantial (Cohen's kappa, 0.849 and 0.871 respectively). CONCLUSION: Preoperative staging with 18F-FDG-PET/MRI is safe and promising with the potential to enhance tissue resolution in the area of interest. 18F-FDG-PET/MRI and 18F-FDG-PET/CT correlated well for most of the measured values and discrepancies were seen mainly in the assessment of the T-stage. These results facilitate further studies investigating the role of 18F-FDG-PET/MRI in, e.g., predicting or determining the response to neoadjuvant therapy.

The exactness of left ventricular segmentation in cine magnetic resonance imaging and its impact on systolic function values.

PURPOSE: To evaluate the impact of exactness of the segmentation of the left ventricle (LV), using cine magnetic resonance imaging (MRI). MATERIAL AND METHODS: Steady-state free-precession cine MRI was performed on 100 randomly selected subjects. Myocardial borders were outlined on short-axis images using three methods: method 1 was computer assisted, excluding papillary muscles from the left ventricular mass (LVM); method 2 was similar but included papillary muscles; and method 3 was manually traced including papillary muscles. LV end-systolic (ES) and end-diastolic (ED) masses and volumes, ejection fraction (EF), stroke volume (SV), and cardiac output (CO) were calculated from these measurements. The difference between the ES and ED LVM was used to estimate the exactness of the methods. RESULTS: Method 3 was the most exact, and method 1 was the least exact. The three methods generated differing EF, SV, and CO measurements. With an ES-ED LVM difference exceeding 20 g, the mean SV measurement error was 8.8+/-3.6 ml. CONCLUSION: Manual tracing proved more exact than computer-assisted quantification. Exactness had an impact on EF, SV, and CO measurements, and the ES-ED LVM difference can be used to identify assessments that would benefit from more exact segmentation.

Treatment of a patient with a nodal peripheral T-cell lymphoma (angioimmunoblastic T-Cell lymphoma) with a human monoclonal antibody against the CD4 antigen (HuMax-CD4).

A patient with a CD4+ refractory peripheral T-cell lymphoma (PTL), subtype angioimmunoblastic T-cell lymphoma (AILD), was treated with a human monoclonal anti-CD4 antibody (HuMax-CD4) iv once weekly for 10 wk. Early during treatment all palpable enlarged lymph nodes disappeared. A decline of normal CD4+ T-cells in the blood mirrored the treatment effect. Shortly after stopping treatment the patient relapsed with new enlarged lymph nodes. This time no antitumor effect was seen when HuMax-CD4 treatment was reinstituted. No severe side effects were observed during the antibody treatment. This case report is the first describing that HuMax-CD4 has antilymphoma activity in PTL and is an interesting drug to study further in patients with CD4+ PTL.

First-pass myocardial perfusion MR imaging with outer-volume suppression and the intravascular contrast agent NC100150 injection: preliminary results in eight patients.

The authors evaluated the feasibility of combining single-shot T2-weighted turbo spin-echo magnetic resonance (MR) imaging and first-pass myocardial perfusion MR imaging with an intravascular ultrasmall superparamagnetic iron oxide (USPIO) contrast agent, NC100150 Injection (3 mg of iron per kilogram of body weight). Eight patients with coronary vessel disease underwent T2-weighted turbo spin-echo MR imaging (in-plane resolution, 1-2 mm) during the first pass of the USPIO contrast agent. The mean decrease in signal intensity in myocardium perfused by a nonstenotic coronary artery was 59% +/- 13 (SD) (P < .012) This method is feasible for imaging of myocardial perfusion.

Contrast agents in acute myocardial infarction.

The experimental design in examination of acute myocardial infarctions should be valid in terms of flow, perfusion and re-flow after intervention. The contrast agents concentration in experimental studies can be measured by microdialysis. We have assessed the usefulness of different extracellular and blood pool contrast agents for visualization of the area at risk in coronary artery occlusions. The double contrast technique, where Dy-DTPA-BMA was combined with Gd-DTPA-BMA yielded a superior infarct visualization. Blood pool agents for example NC100/150 injection is also promising in first path myocardial perfusion imaging.

Energy-related metabolites during and after induced myocardial infarction with special emphasis on the reperfusion injury after extracorporeal circulation.

In the clinical setting great efforts have been made with contradictory results to operate upon acutely myocardial ischaemic patients. The reasons for the absence of clear-cut results are not well understood nor are they scientifically explored. To resolve this problem further, we attempted to design an experimental in vivo model to mimic acute myocardial ischaemia followed by extracorporeal circulation (ECC) and reperfusion. One of the main targets of our protocol was monitoring of myocardial energy metabolism by microdialysis (MCD) during the periods of coronary occlusion (60 min), hypothermic (30 degrees C) ECC and cardioplegia (45 min), followed by reperfusion with (30 min) and without (60 min) ECC. In eight anaesthetized, open-chest pigs, myocardial lactate, pyruvate, adenosine, taurine, inosine, hypoxanthine and guanosine were sampled with MCD in both ischaemic and non-ischaemic areas. Myocardial area at risk and infarct size were quantified with the modified topographical evaluation methods. The principal finding with this experimental setup was a biphasic release pattern of lactate, adenosine, taurine, inosine, hypoxanthine and guanosine from ischaemic myocardium. Lactate levels were equally high in reperfused ischaemic and non-ischaemic myocardial tissue. Pyruvate demonstrated consistently higher values in non-ischaemic myocardium throughout the experiment. A pattern was discernible, lactate being a marker of compromised cell energy metabolism, and taurine being a marker of disturbed cell integrity. Of special interest was the increased level of pyruvate in microdialysates of non-ischaemic myocardium as compared with its ischaemic counterpart. In conclusion, we found disturbances in energy metabolism and cell integrity not only in ischaemic but also in non-ischaemic tissue during reperfusion implying that non-ischaemic myocardium demonstrated an unexpected accumulation of lactate and pyruvate. These new findings could at least partly be explicatory to the increased risk of heart surgery in connection with acute myocardial infarction.

Discrepant outcome between myocardial energy-related metabolites and infarct size limitation during retroperfusion of the coronary sinus.

The basic idea of retroperfusion of the coronary sinus (RCS) is to ameliorate detrimental consequences of myocardial ischaemia. Several experimental models of RCS have been introduced, most with an emphasis on functional myocardial status. Since only few studies have been devoted to energy metabolic considerations and none to continuous monitoring of energy-related metabolites of myocardium during RCS, we here present such a study using microdialysis. This study comprised the following components: Coronary occlusion and drainage on the beating heart with RCS-assist (60 min), hypothermic (30 degrees C) extracorporeal circulation (ECC) and cardioplegia (45 min), reperfusion and rewarming to 38 degrees C on ECC (30 min). The microdialysis analytical outcome mainly reflected anaerobic energy metabolism in potentially ischaemic myocardium. Additionally, a pronounced increase of microdialysate content of lactate, pyruvate and guanosine was observed in non-ischaemic myocardium especially during the reperfusion phase. The planimetric calculation revealed an infarct size reduction from 69% to 19% and was not correlated to clear-cut improvements of potentially ischaemic myocardial energy metabolism. We conclude that prolonged (60 min) anaerobic energy metabolism does not pose an immediate threat to cell viability but could even sustain myocyte survival.

Evaluation of nonperfused myocardial ischemia with MRI and an intravascular USPIO contrast agent in an ex vivo pig model.

The ultrasmall superparamagnetic iron oxide (USPIO) preparation NC100150 Injection (Clariscan; Nycomed Imaging, Oslo, Norway) was tested for its ability to delineate nonperfused myocardium under steady-state conditions. An experimental animal model of focal myocardial ischemia induced by ligation of the distal part of the left anterior descending artery was used. The contrast agent was administered in four doses: 0, 4, 8, and 12 mg Fe/kg body weight. Magnetic resonance examination ex vivo, including T1-, T2-, and T2*-weighted sequences, was performed. Nonperfused myocardium was determined by fluorescein. The best delineation of nonperfused myocardium was found with a T1-weighted inversion recovery/turbo spin-echo sequence and doses of 4 and 8 mg Fe/kg body weight, where 95% of the volume was discernible at the dose of 4 mg Fe/kg body weight. The results suggest that steady-state imaging by T1-weighted sequence with the use of NC100150 Injection to delineate nonperfused myocardium is feasible. J. Magn. Reson. Imaging 2000;12:866-872.

3D surface rendering of images from multiple MR pulse sequences in the pre-operative evaluation of hepatic lesions.

PURPOSE: To develop a method for making three-dimensional (3D) reconstructions of liver vessels and hepatic lesions from different MR data sets. MATERIAL AND METHODS: To reduce the time required for segmentation and reconstructions, we used T1, T2 and phase contrast angiography, optimised for liver, lesion and vessels respectively. Following segmentation and reconstruction, the different volumes were combined on the same workstation and presented to the surgeon. RESULTS AND CONCLUSION: Segmentation and reconstruction took 1-2 h. To be able to combine the volumes from the different data sets, certain criteria had to be fulfilled: a) the field of view had to be constant; b) the same volume had to be scanned every time which meant that the slice thickness and the number of slices could be adjusted as long as the volume covered was the same; and c) the positioning of each volume had to be identical between every scan. The resulting 3D reconstruction gave the surgeon a clear appreciation of the different lesions and their relation to the different liver segments in the pre-operative planning of hepatic resections.