P5284Fully automated quantification of biventricular volumes and function in cardiovascular magnetic resonance: applicability to clinical routine settings

Background

Cardiovascular magnetic resonance (CMR) represents the clinical gold standard for the assessment of biventricular morphology and function. Since manual post-processing is time-consuming and prone to observer variability, efforts have been directed towards automated volumetric quantification. In this study, we sought to validate the accuracy of a novel approach providing fully automated quantification of biventricular volumes and function in a “real-world” clinical setting.

Methods

Three-hundred CMR examinations were randomly selected from the local data base. Fully automatic quantification of left ventricular (LV) mass, LV and right ventricular (RV) end-diastolic and systolic volumes (EDV/ESV), stroke volume (SV) and ejection fraction (EF) were performed overnight using commercially available software. Parameters were compared to manual assessments. Sub-group analyses were further performed according to image quality, scanner field strength, the presence of implanted aortic valves and repaired Tetralogy of Fallot (ToF).

Results

Biventricular automatic segmentation was feasible in all 300 cases. Overall agreement between fully automated and manually derived LV parameters was good (LV-EF: intra-class correlation coefficient [ICC] 0.95; bias −2.5% [SD 5.9%]), whilst RV agreement was lower (RV-EF: ICC 0.72; bias 5.8% [SD 9.6%]). Lowest agreement was observed in case of severely altered anatomy, e.g. marked RV dilation but normal LV dimensions in repaired ToF (LV parameters ICC 0.73–0.91; RV parameters ICC 0.41–0.94) and/or reduced image quality (LV parameters ICC 0.86–0.95; RV parameters ICC 0.56–0.91), which was more common on 3.0T than on 1.5T.

Conclusions

Fully automated assessment of biventricular morphology and function is robust and accurate in a clinical routine setting with good image quality and can be performed without any user interaction. However, in case of demanding anatomy (e.g. repaired ToF, severe LV hypertrophy) or reduced image quality, quality check and manual re-contouring is still required.

Acknowledgement/Funding

DZHK - German Centre for Cardiovascular Research

Pelvic lymph node dissection for nodal oligometastatic prostate cancer detected by 68Ga-PSMA-positron emission tomography/computerized tomography

BACKGROUND

The first evaluation of pelvic extended lymph node dissection (pLND) in oligometastatic prostate cancer (PCa) detected by (68)Ga-PSMA PET/CT.

METHODS

Retrospective analysis of 35 PCa patients underwent (68)Ga-PSMA PET/CT affected by biochemical recurrence (BCR) after curative treatment (n = 23) or before primary therapy of high-risk PCa (n = 12). We performed pLND associated with pathologic imaging in 17 men with nodal oligometastatic PCa.

RESULTS

Indicative lesions for PCa in PET/CT were detected in 91.4% (32 of 35) of patients. Nodal, bone, visceral (pulmonary), and within the prostate suspected disease were detected in 72% (23 of 32), 16% (5 of 32), 6% (2 of 32), and 47% (15 of 32) of patients, respectively. Median serum PSA in patients with pathological radiotracer uptake in recurrent and high-risk PCa patients was 2.9 ng/ml (range 0.18-30) and 19.5 ng/ml (range 6-90), respectively. The median number of removed lymph nodes with pLND in recurrent and high-risk PCa was 10 (range 4-17) and 12 (range 8-29) per patient and the median number of positive lymph nodes was 1 (range 1-2) and 3 (2-3) per patient, respectively. In total, two false positive and one false-negative lymph node were found. Diagnostic accuracies per nodal lesion in total of 213 removed nodes: sensitivity, 94%; specificity, 99%; positive predictive value (PPV), 89%, and negative predictive value (NPV), 99.5%. After pLND, 53% (9 of 17) of patients received androgen deprivation therapy and/or radiation therapy and hormonal therapy, while 47% (8 of 17) of patients remained free of any post-surgery therapy. Follow-up PSA remained less than 0.2 ng/ml in 82% (14 of 17) of patients. After pLND, immediate BCR (PSA never measured less than 0.2 ng/ml) in 18% (3 of 17) of patients was recorded.

CONCLUSIONS

This represents the first study of pLND in the setting of nodal oligometastatic PCa detected by (68)Ga-PSMA PET/CT. The use of (68)Ga-PSMA PET/CT could be to improve the accuracy for the detection of nodal micrometastases. These promising findings need validation in larger studies.

Quantitative pixelwise myocardial perfusion maps from first-pass perfusion MRI

OBJECTIVE

To calculate and evaluate absolute quantitative myocardial perfusion maps from rest first-pass perfusion MRI.

METHODS

10 patients after revascularization of myocardial infarction underwent cardiac rest first-pass perfusion MRI. Additionally, perfusion examinations were performed in 12 healthy volunteers. Quantitative myocardial perfusion maps were calculated by using a deconvolution technique, and results were compared were the findings of a sector-based quantification.

RESULTS

Maps were typically calculated within 3 min per slice. For the volunteers, myocardial blood flow values of the maps were 0.51 ± 0.16 ml g(-1) per minute, whereas sector-based evaluation delivered 0.52 ± 0.15 ml g(-1) per minute. A t-test revealed no statistical difference between the two sets of values. For the patients, all perfusion defects visually detected in the dynamic perfusion series could be correctly reproduced in the maps.

CONCLUSION

Calculation of quantitative perfusion maps from myocardial perfusion MRI examinations is feasible. The absolute quantitative maps provide additional information on the transmurality of perfusion defects compared with the visual evaluation of the perfusion series and offer a convenient way to present perfusion MRI findings.

ADVANCES IN KNOWLEDGE

Voxelwise analysis of myocardial perfusion helps clinicians to assess the degree of tissue damage, and the resulting maps are a good tool to present findings to patients.

[Splenomegaly with multiple unclear parenchymal lesions. Splenomegaly]

A 53-year-old female patient presented with splenomegaly, uncertain lesions of the spleen, pancytopenia and suspected aortitis. Reduced strength and muscular pain but no B symptoms were also present. Alterations of the spleen had been known for a long time. Blood examination, laboratory tests and magnetic resonance imaging (MRI) confirmed an aortitis. Concerning the splenic changes neither ultrasound nor MRI could provide conclusive or even pathognomonic findings. Because of an existing pancytopenia and diagnostic obscurity, the patient underwent splenectomy. The histological diagnosis was finally concluded as multifocal littoral cell angioma.

Quantitative myocardial perfusion imaging with a MR cold pressor test

The response of myocardial blood flow to sympathetic stimulation with cold is modulated by endothelium-related factors. As endothelial dysfunction is an early step in patients with coronary artery disease, the aim of this study was to establish a cold pressor test (CPT) setting for quantitative analysis of myocardial perfusion in a MR scanner. First pass perfusion studies were performed in 10 healthy volunteers using a 1.5 T MR scanner with a multislice steady state free precession perfusion trueFISP sequence in prebolus technique (1 cc/4 cc gadobenate dimeglumine). MR-CPT was established using an over head ice-water bath of the left hand. First pass perfusion imaging was started after 1 min to assure an adequate stimulus followed by a second series after 15 min to evaluate the rest perfusion. After motion correction images were segmented with an adapted, automated tool, myocardial contours were determined. Perfusion was quantitatively evaluated after contamination and baseline correction by deconvolution with the arterial input function using an exponential function model as residuum. All data could be evaluated. Mean myocardial perfusion rose from 0.61 ± 0.22 cc/g/min at rest to 1.15 ± 0.34 cc/g/min under CPT. MR myocardial perfusion values show a comparable increase under CPT as published positron emission tomography data. Consequently, CPT for the presence of endothelial dysfunction is feasible in the MR environment.

[High-resolution MRI for the quantitative evaluation of subendocardial and subepicardial perfusion under pharmacological stress and at rest]

PURPOSE

MR stress perfusion imaging of the heart allows the quantification of myocardial perfusion and the evaluation of myocardial perfusion reserve (MPR) and the ratio of subendocardial to subepicardial perfusion at rest and under adenosine stress. The aim of this study was to evaluate a high-resolution GRAPPA sequence for quantitative MR first pass perfusion imaging in healthy volunteers.

MATERIALS AND METHODS

First pass stress and rest perfusion studies were performed on 10 healthy volunteers using a 1.5 T MR scanner with a multislice SR-TrueFISP first pass perfusion sequence with a GRAPPA algorithm (acceleration factor 3) in prebolus technique and an image resolution of 1.8 x 1.8 mm. For the comparison group, we examined 12 different healthy volunteers with a standard first pass perfusion SR-TrueFISP sequence using a resolution of 2.7 x 3.3 mm. Myocardial contours were manually delineated followed by an automatic division of the myocardium into two rings with an equal thickness for the subendo- and subepicardial layer. Eight sectors per slice were evaluated using contamination and baseline correction.

RESULTS

Using the GRAPPA sequence, the ratio of subendo- to subepimyocardial perfusion was 1.18 +/- 0.32 for the examination at rest. Under pharmacologically induced stress, the ratio was 1.08 +/- 0.27. For the standard sequence the ratio was 1.15 +/- 0.28 at rest and 1.11 +/- 0.33 under stress. For the high resolution sequence higher mean values for the subendo- to subepimyocardial ratio were obtained with comparable standard deviations. The difference between the sequences was not significant.

CONCLUSION

The evaluation of subendomyocardial and subepimyocardial perfusion is feasible with a high-resolution first pass perfusion sequence. The use of a higher resolution to avoid systematic error leads to increased image noise. However, no relevant reduction in the quantitative perfusion values under stress and at rest was able to be depicted.

MR-Bildgebung und MR-Spektroskopie zur Charakterisierung von Kardiomyopathien bei Jugendlichen - erste Ergebnisse

PURPOSE

Cardiomyopathy is a rare but life-threatening disease in children and adolescents. Recent studies reported morphological, functional or metabolic alterations of the heart. We discuss a combined MR imaging and (31)P MR spectroscopy (MRS) protocol allowing the analysis of interdependencies between these parameters. Since normal values of cardiac MR parameters in this age group are not available, we included studies of age-matched healthy adolescents.

MATERIALS AND METHODS

2D-CINE was used to assess left ventricular (LV) parameters. Additional 3D-Chemical Shift Imaging (3D-CSI) and Spectral Localization with Optimal Pointspread Function (SLOOP) reconstruction allowed quantification of the cardiac energy metabolism. Patients (n = 4; all male; age 16.8 +/- 2.9 years) were included on the basis of an echocardiographic diagnosis of possible cardiomyopathy. The same protocol was applied to healthy young volunteers (n = 4; 1 female, 3 male; age 15.5 +/- 0.6 years).

RESULTS

The patients had a significantly higher LV mass index compared to the control group (147 +/- 41 g/m (2) versus 97 +/- 16 g/m2; p = 0.04). The other LV parameters (including LV EF with 59 +/- 22 % versus 67 +/- 10 %) showed no significant differences. The phosphocreatine to adenosine triphosphate ratio (PCr/ATP-ratio) of the patients was reduced to 1.71 +/- 0.40 versus 2.44 +/- 0.30 (p = 0.01), combined with a tendency towards decreased PCr concentrations of 9.1 +/- 2.5 versus 7.9 +/- 1.0 mmol/kg.

CONCLUSION

The combination of (31)P MR spectroscopy and MR imaging allows quantitative determination of morphologic, functional and metabolic alterations in adolescents with suspected cardiomyopathy in one examination procedure. The reduction of energy metabolism combined with unaltered global function may indicate a primary role of metabolism in the pathogenesis of cardiomyopathies in adolescents.

Bestimmung des koronaren Kalzium-Scores mittels 64-Zeilen-CT - Variabilität der Scores und Einfluss des Rekonstruktionszeitpunktes

PURPOSE

To evaluate the variability of coronary calcium scores depending on the image reconstruction interval using a 64-slice CT scanner.

MATERIALS AND METHODS

30 patients (18 male, 12 female; mean age 57 +/- 9 yrs; mean heart rate 66 +/- 10 bpm) underwent coronary calcium scoring using a 64-slice CT scanner (Somatom Sensation 64, Siemens Medical Solutions, Erlangen) and a standardized scanning protocol. Oral beta-blockers were administered to 12 patients with a baseline heart rate > 70 bpm. Images were reconstructed in 10 % increments from 10 - 100 % of the RR interval. Two blinded experienced observers independently calculated Agatston (AS), calcium mass (MS) and volume scores (VS) for every reconstructed image series. The results were compared to similar studies for 16-slice CT scanners.

RESULTS

The mean values and mean coefficients of variation among all patients were as follows: AS, 397 +/- 829, 109 % MS, 88 +/- 225, 154 % VS, 335 +/- 669, 100 %. Regarding the reconstruction intervals, the mean coefficients of variation were as follows: 107 % (AS), 97 % (VS), 116 % (MS). No specific image reconstruction interval with statistically significant lower variability for each score could be identified. High inter-observer agreement was achieved (K = 0.98). With statistical significance (p < 0.05) 10/30 patients (pts) were able to be allocated to more than one risk group (RG): 6 pts = 2 RG; 3 pts = 3 RG; 1 pts = 4 RG. The scores for 5/30 patients were zero for at least one reconstruction interval, but further reconstructions revealed calcifications. The number of patients assignable to different risk groups was significantly lower compared to published data using a 16-slice scanner (p < 0.05).

CONCLUSION

Coronary calcium scores determined using a 64-slice scanner display a wide range of variability depending on the image reconstruction interval as already described for 16-slice CT scanners. However, compared to previous studies, our data indicate that this vendor's generation of scanners reduces the influence of score variations on the risk stratification.

Differential pulse polarographic determination of 2,3-dimercaptosuccinic acid and tin (II) in radiopharmaceuticals

A differential pulse polarographic procedure was developed for the assay of dimercaptosuccinic acid and tin(II), components of a commercially available pharmaceutical kit for kidney scintigraphy. The method is quantitative and qualitative for both the chelated and unchelated forms of dimercaptosuccinic acid and tin(II) in a mixture of the two.