Feature tracking cardiovascular magnetic resonance reveals recovery of atrial function after acute myocarditis.

Follow-up after acute myocarditis is important to detect persisting myocardial dysfunction. However, recovery of atrial function has not been evaluated after acute myocarditis so far. Thirty-five patients with strictly defined acute myocarditis underwent cardiovascular magnetic resonance (CMR, 1.5 T) in the acute stage at baseline (BL) and at 3 months follow-up (FU). The study population included 13 patients with biopsy-proven "cardiomyopathy-like" myocarditis (CLM) and 22 patients with "infarct-like" (ILM) clinical presentation. CMR feature tracking (FT) was performed on conventional cine SSFP sequences. Median LA-GLS increased from 33.2 (14.5; 39.2) at BL to 37.0% (25.2; 44.1, P = 0.0018) at FU in the entire study population. Median LA-GLS also increased from 36.7 (26.5; 42.3) at BL to 41.3% (34.5; 44.8, P = 0.0262) at FU in the ILM subgroup and from 11.3 (6.4; 21.1) at BL to 21.4% (14.2; 30.7, P = 0.0186) at FU in the CLM subgroup. Median RA-GLS significantly increased from BL with 30.8 (22.5; 37.0) to FU with 33.7% (26.8; 45.4, P = 0.0027) in the entire study population. Median RA-GLS also significantly increased from 32.7 (25.8; 41.0) at BL to 35.8% (27.7; 48.0, P = 0.0495) at FU in the ILM subgroup and from 22.8 (13.1; 33.9) at BL to 31.0% (26.0; 40.8, P = 0.0266) at FU in the CLM subgroup. Our findings demonstrate recovery of LA and RA function by CMR-FT strain analyses in patients after acute myocarditis independent from clinical presentation. Monitoring of atrial strain could be an important tool for an individual assessment of healing after acute myocarditis.

Tissue characterization by T1 and T2 mapping cardiovascular magnetic resonance imaging to monitor myocardial inflammation in healing myocarditis.

AIMS: Monitoring disease activity in myocarditis is important for tailored therapeutic strategies. This study evaluated the ability of T1 and T2 mapping cardiovascular magnetic resonance (CMR) to monitor the course of myocardial inflammation in healing myocarditis. METHODS AND RESULTS: Forty-eight patients with strictly defined acute myocarditis underwent CMR at 1.5 T in the acute stage, at 3-months (n = 39), and at 12-months follow-up (FU) (n = 21). Normal values were obtained in a control group of 27 healthy subjects. The CMR protocol included standard ('Lake-Louise') sequences as well as T1 (modified Look-Locker inversion recovery sequence, MOLLI) and T2 (gradient- and spin-echo sequence, GraSE) mapping. T1, T2, and extracellular volume (ECV) maps were generated using an OsiriX plug-in. Native myocardial T1, T2, and ECV values were increased in the acute stage, but declined with healing of myocarditis. The performances of global native T1 and T2 to differentiate acute from healed myocarditis stages were significantly better compared with all other global CMR parameters with AUCs of 0.85 (95% CI, 0.76-0.94) and 0.83 (95% CI, 0.73-0.93). Furthermore, regional native T1 and T2 in myocarditis lesions provided AUCs of 0.97 (95% CI, 0.93-1.02) and 0.93 (95% CI, 0.85-1.01), which were significantly superior to any other global or regional CMR parameter. CONCLUSION: Healing of myocarditis can be monitored by native myocardial T1 and T2 measurements without the need for contrast media. Both native myocardial T1 and T2 provide an excellent performance for assessing the stage of myocarditis by CMR.

Technical note: A comparison of DNA collection methods in cattle and yaks.

A variety of biological materials are suitable for the analysis of bovine DNA. The objective of this study was to evaluate the ease of collection, storage, and cost as well as quality and quantity of DNA samples obtained from Bos taurus (European cattle) and Bos grunniens (yak) using 2 different sample types: whole blood sampling and nasal swabs. Hair follicle DNA samples from yaks were also analyzed. Deoxyribonucleic acid samples were collected from 1 herd of Black Angus yearling bulls (n = 166) and 1 herd of yaks (n = 24). A NanoDrop Bioanalyzer ND1000 was used to quantify DNA. To assess DNA purity, absorbance ratios were determined at wavelengths of 260 nm relative to 280 nm and 260 nm relative to 230 nm. Single nucleotide polymorphism genotyping was performed using a competitive allele-specific PCR (KASP) genotyping system and the call rates to 3 specific SNP were compared. Using a commercially available nonautomated ethanol DNA extraction technique, nasal swabs yielded a greater quantity of DNA than blood (P < 0.0001) and a greater quality DNA sample than blood (P < 0.0001). Blood and nasal swab performance in SNP genotyping assays were similar (P = 0.5). The greater expense of nasal swabs was offset by their ease of use: less time, skill, and equipment was needed to obtain a sample and the storage of samples was more convenient (room temperature). In yaks, accessing the coccygeal vein, which is relatively straightforward in cattle, was difficult. Nasal swabbing and hair follicle sampling in yaks was performed relatively easily. Yak hair follicles were a poor source of DNA. In conclusion, DNA collection using nasal swabs was more convenient and provided a greater quantity of DNA and better quality sample than blood collection in both Angus and yak. Notably, yak hair was a poor source of DNA, and yak blood was difficult to obtain.

Improved agreement between experienced and inexperienced observers using a standardized evaluation protocol for cardiac volumetry and infarct size measurement.

PURPOSE: To study the agreement between experienced and inexperienced observers before and after training using a standardized evaluation protocol for cardiac magnetic resonance imaging (CMR) measurements of left ventricular (LV) volumes, mass and infarct size. MATERIALS AND METHODS: First, 10 CMR studies from patients with myocardial infarction were analyzed by 2 experienced and 4 inexperienced observers in respect to end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF), LV mass and infarct size. Subsequently, the inexperienced observers were trained using a standardized evaluation protocol. Thereafter, all observers analyzed another 10 CMR studies. RESULTS: Before training the relative difference between experienced and inexperienced observers was -4.3±8.2% for EDV, -13.3±14.2% for ESV, 5.9±8.2% for EF, -12.2±10.9% for LV mass and -27.0±29.0% for infarct size in gram. After training, agreement significantly improved to 0.2±8.8% for EDV (p<0.05), -2.1±10.9 for ESV (p<0.01), 1.5±6.9% for EF (p<0.05), and -3.6±17.1% for infarct size (p<0.0001), but no improvement was seen for LV mass (-11.2±7.9, p=0.64). A slice based analysis showed, that the variable inclusion of the most basal and apical slices were mainly responsible for the low agreement of the measurements before training. CONCLUSION: Training using a standardized evaluation protocol significantly improved the agreement between experienced and inexperienced observers for important CMR parameters. The proposed evaluation protocol can be used for training to improve the reproducibility of CMR measurements.

Assessment of myocardial viability in ischemic heart disease by cardiac magnetic resonance imaging.

Assessment of myocardial viability aims at differentiating between viable and non-viable myocardium. The proof of dysfunctional but viable myocardium is crucial to predict outcome of revascularization after acute (AMI) and chronic myocardial infarction (CMI). Cardiac magnetic resonance imaging (CMRI) offers different options to detect viable myocardium: Measurements of end-diastolic wall thickness by cine-CMRI can be used to depict chronically scarred myocardium, but fails to detect acute myocardial necrosis. Low-dose dobutamine stimulation (LDDS) cine-CMRI analyses the contractile reserve of dysfunctional but viable myocardium under pharmacologic stimulus to identify viable myocardium in AMI and CMI with high specificity. Sensitivity of LDDS cine-CMRI is superior to LDDS echocardiography but reduced in patients with severely impaired left ventricular (LV) function. The delayed-enhancement (DE) technique directly visualises non-viable myocardium due to an altered contrast-media distribution in necrotic and fibrotic tissue. DE-CMRI identifies non-viable myocardium with high spatial resolution independently from LV function. The transmural extent of contrast enhancement in DE-CMRI is used to predict functional recovery after revascularization in AMI and CMI. Furthermore, the amount and pattern of contrast enhancement in DE-CMRI provide important prognostic information in both entities. Recent studies demonstrated the superiority of DE-CMRI compared to single photon emission tomography (SPECT) and positron emission tomography (PET) to assess myocardial viability. Therefore, DE-CMRI is currently recognised as the standard of reference for assessment of myocardial viability. The technical background, clinical application and accuracy of the different CMRI techniques to assess myocardial viability in AMI and CMI are discussed in this work.

Assessment of functional anatomy of the mitral valve in patients with mitral regurgitation with cine magnetic resonance imaging: comparison with transesophageal echocardiography and surgical results.

The ability of magnetic resonance imaging (MRI) to accurately define the functional anatomy of mitral regurgitation was assessed. Transesophageal echocardiography (TEE) and cine MRI were performed on 43 patients with mitral regurgitation and were compared for the jet number, location, direction and presence of a prolapse (atrial displacement, malapposition or a flail). In 36 patients, diagnostic accuracy in reference to surgery was assessed. Comparing TEE and MRI the jet number and location were judged in concordance in 86% of patients. Jet location did not show a significant difference (Wilcoxon: P = 0.66) and both modalities correlated strongly (Spearman: r = 0.68, P<0.0001). Jet direction was judged with high concordance (kappa=0.63). Additionally, prolapse evaluation showed high concordance (kappa: valve, 0.63; anterior mitral leaflet, 0.70; posterior mitral leaflet, 0.73). Compared with surgery, the sensitivity for the detection of malapposition of any leaflet or one of both leaflets ranged between 75% and 93% for TEE and 71% and 89% for MRI. Specificities ranged between 88 and 96% for TEE and 88 and 100% for MRI. TEE detected torn chordae in all ten patients, six of which were missed by MRI. MRI is comparable with TEE in prolapse and jet evaluation. MRI is inferior to TEE in depicting anatomical details such as torn chordae.

[Patterns of delayed-enhancement in MRI of ischemic and non-ischemic cardiomyopathies]. / Muster der späten Kontrastmittelanreicherung in der MRT bei ischämischen und nicht-ischämischen Kardiomyopathien.

Contrast-enhanced MRI using the delayed-enhancement technique (DE-MRI) is widely applied in the clinical work-up of myocardial diseases. Myocardial diseases of varying etiology result in myocardial changes, such as necrosis, fibrosis, edema and metabolite deposition, which can be visualized by DE-MRI. Acute and chronic ischemic diseases based on a coronary artery disease as well as non-ischemic cardiomyopathies display DE. Cardiomyopathies often show a characteristic enhancement pattern. While ischemic lesions are localized in the subendocardium, non-ischemic cardiomyopathies often display an intramyocardial or subepicardial pattern. The typical pattern for dilated cardiomyopathies is band-like and intramyocardial with septal involvement. Arrhythmogenic right-ventricular dysplasias/cardiomyopathies are frequently associated with right-ventricular DE. In the case of amyloid cardiomyopathies which are often restrictive cardiomyopathies, subendocardial and circular DE is typically observed. Hypertrophic cardiomyopathies display patchy intramyocardial DE usually in the anteroseptal region. Acute myocarditis is typically accompanied by intramyocardial or subepicardial DE affecting the lateral wall. In the case of chronic myocarditis, intramyocardial or subepicardial DE is observed most frequently. Cardiac sarcoidosis typically entails patchy subepicardial DE with right- and left-ventricular involvement. Since there is an overlap between the enhancement patterns of cardiomyopathies, the diagnostic accuracy of DE-MRI is limited and the diagnosis must be based on additional clinical and MRI findings. The amount of DE often corresponds with cardiac functional parameters as well as with the frequency of cardiac events so that DE-MRI may be useful for risk stratification. Furthermore, DE-MRI can be helpful in the planning and evaluation of myocardial biopsies and electrophysiological examinations.

Computer-assisted analysis of 4D cardiac MR image sequences after myocardial infarction.

OBJECTIVES: Spatial-temporal MR image sequences of the heart contain information about shape and motion changes and pathological structures after myocardial infarction. In this paper a Heart Analysis Tool (HeAT) for the quantitative analysis of 4D MR image sequences of infarct patients is presented. METHODS: HeAT supports interactive segmentation of anatomical and pathological structures. Registration of Cine- and DE-MR image data is applied to enable their combined evaluation during the analysis process. Partitioning of the myocardium in segments enables the analysis with high local resolution. Corresponding segments are generated and used for inter/intrapatient comparison. Quantitative parameters were extracted and visualized. RESULTS: Parameters like endocard movement in the infarcted area of six infarct patients were computed in HeAT. Parameters in the infarct area show the expected dysfunctional characteristics. Based on theses parameters passive endocardial movement and myocardial areas with decreased contraction could be identified. CONCLUSION: In contrast to other software tools HeAT supports the combination of contour information of Cine-MR and DE-MR, local analysis with high resolution and inter/intra patient comparison. HeAT enables an observer-independent evaluation of the complex cardiac image data. Using HeAT in further studies can increase the understanding of left ventricle (LV) remodeling.

Coronary artery anomalies Part II: recent insights from clinical investigations.

Congenital anomalies of the coronary arteries occur in 0.2-1.2% of the general population; they cause 12% of sports-related sudden cardiac deaths and 1.2% of non-sports-related deaths. We review some of the substantial advances that have been made both, in the understanding of the embryonic development of the coronary arteries and in the clinical diagnosis and management of their anomalies. In this second part of our review we elucidate recent approaches to defining coronary anomalies and provide information on their incidence and prognosis. In addition, we discuss the options for screening large populations for potentially lethal coronary malformations and elucidate the role of invasive diagnostic modalities such as intravascular ultrasound, flow wire and pressure wire. The clinical relevance of coronary anomalies is discussed particularly for the ill-defined group of anomalies that only occasionally cause severe clinical events comprising anomalous origination of a coronary artery from the opposite sinus (ACAOS), coronary artery fistulae and myocardial bridging. Finally, we provide an update on current diagnostic and therapeutic recommendations.

Coronary artery anomalies. Part I: Recent insights from molecular embryology.

Congenital anomalies of the coronary arteries occur in 0.2-1.2% of the general population and may cause substantial cardiovascular morbidity and mortality. We review some of the advances that have been made both, in the understanding of the embryonic development of the coronary arteries (part I) and in the clinical diagnosis and management of their anomalies (part II). In this first part of our review we elucidate basic mechanisms of coronary vasculogenesis, angiogenesis and embryonic arteriogenesis. Moreover, we review the role of cellular progenitors such as epicardium-derived cells, cardiac neural crest cells and cells of the peripheral conduction system. Then we discuss the role of growths factors (such as FGV, HIF 1, PDGF B, TGFbeta1, VEGF, and VEGFR-2) and genes (such as FOG-2, VCAM-1, Bves, and RALDH2) at different states of coronary development. and we discuss the role of the cardiac neural crest in the concurrence of coronary anomalies with aortic root malformations. This part of the article is designed to review major determinants of coronary vascular development to provide a better understanding of the multiplicity of options and mechanisms that may give rise to coronary anomaly. To this end, we highlight results from experiments that provide insight in mechanisms of coronary malformation.

Evaluation of balanced steady-state free precession (TrueFISP) and K-space segmented gradient echo sequences for 3D coronary MR angiography with navigator gating at 3 Tesla.

PURPOSE: To test the feasibility of k-space segmented gradient-echo pulse sequences for free-breathing coronary magnetic resonance angiography (cMRA) on a clinical 3T system. MATERIALS AND METHODS: T2-prepared, fat-suppressed turbo field echo (TFE, turboFLASH, SFPGR) as well as balanced TFE (b-TFE, trueFISP, FIESTA, segmented SSFP) sequences with navigator gating for prospective motion correction were applied on a 3T system equipped with a six-element phased-array cardiac coil. In 15 healthy volunteers, the right coronary artery (RCA) was examined with TFE and b-TFE sequences. Due to examination time limitations, the left coronary artery (LM/LAD) was examined exclusively with the TFE sequence in ten volunteers. Image quality was graded on a five point scale (0 = not visualized to 4 = excellent). The length, diameter and sharpness of the vessels and the contrast-to-noise ratios (CNR) were measured. RESULTS: 98 % of all major segments (proximal/middle/distal) of the RCA could be seen with the TFE sequence and 82 % with the b-TFE sequence. The image quality for the three segments was graded higher for the TFE sequence (2.7/2.7/1.5) than for the b-TFE sequence (1.9/1.6/0.9) with P: (< or = 0.001/< or = 0.004/< or = 0.056). The kappa of the interobserver variability was 0.75 for the TFE sequence and 0.8 for the b-TFE sequence. The measured vessel lengths were longer for the TFE sequence (95 +/- 22 mm) than for the b-TFE sequence (80 +/- 40 mm; P < or = 0.115). No significant changes (P < or = 0.074, P < or = 0.145) in diameter and vessel sharpness of the RCAs were observed between the TFE (2.4 +/- 0.3 mm, 60 % +/- 5) and b-TFE sequences (2.4 +/- 0.3 mm, 62 % +/- 6). The CNR was higher for the TFE sequence (10.1 +/- 3.4) than for the b-TFE sequence (6.6 +/- 2.1; P < or = 0.014). All ten main and proximal segments of the LM/LAD, which were examined exclusively with the TFE sequence, were visible with grade 2.5 and 2.1. The middle segment was visible in seven cases with grade 1.3. In three cases, the distal segment was visible with grade 0.5. The vessel length was 78 +/- 27 mm and the CNR 11.9 +/- 2.4. CONCLUSION: The conventional TFE technique has demonstrated good feasibility for cMRA at 3T. In its operational availability at 3T, the b-TFE sequence is inferior to the TFE sequence.

[Comparison of an edema-sensitive HASTE-TIRM sequence with delayed contrast enhancement in acute myocardial infarcts]. / Vergleich der ödemsensitiven HASTE-TIRM-Sequenz mit der späten Kontrastmittelanreicherung bei akutem Myokardinfarkt.

GOAL: Comparison between a fluid-sensitive (HASTE-TIRM)-sequence and delayed contrast-enhancement in patients with acute myocardial infarct (AMI) in MRI. MATERIAL AND METHODS: 32 patients with AMI were imaged 7 +/- 4 days after the time of infarction with a 1.5 T unit using a T2 HASTE-TIRM and a contrast-enhanced (CE) T1 turbo FLASH sequence. A threshold method (>2 SD in comparison with normal myocardium) was used to quantify the hyperintense zones in both sequences. The transmurality of the hyperintense regions was measured on a segmental basis. RESULTS: The hyperintense areas were larger on the HASTE-TIRM sequence with 29.6 +/- 13.2 % of the left ventricular (LV) area as compared to the CE-MRI with 19.2 +/- 10 % of the LV area (p < 0.0001). The measured transmurality was higher with the HASTE-TIRM sequence than with the CE-MRI (p < 0.0001). While the correlation between CE-MRI and peak creatine kinase (CK max) was good (r = 0.59, p < 0.001), no correlation was found between the HASTE-TIRM sequence and CK max (r = 0.29, p = ns). CONCLUSIONS: The peri-infarct edema can be depicted with a HASTE-TIRM sequence in addition to the non-viable infarct zone. The HASTE-TIRM sequence shows a higher transmurality of the hyperintense regions than the CE-MRI. The additional area depicted by the HASTE-TIRM sequence could represent functionally impaired but viable myocardium).

Prediction of left ventricular functional recovery by dobutamine echocardiography, F-18 deoxyglucose or 99mTc sestamibi nuclear imaging in patients with chronic myocardial infarction.

BACKGROUND: Currently, several modalities are available to predict viability, however, studies comparing various modalities validated by functional recovery after revascularization are scarce. This study analyzed the relative merits of low-dose dobutamine echocardiography, F-18 deoxyglucose (FDG) positron emission tomography (PET) and (99m)Tc sestamibi single-photon emission computed tomography to predict functional recovery after revascularization in patients with chronic myocardial infarction. METHODS: Patients with chronic coronary occlusion (duration: 3.1 +/- 4.8 years) and impaired left ventricular function (ejection fraction: 42 +/- 13%) underwent low-dose dobutamine echocardiography (20 microg/kg/min), FDG-PET and (99m)Tc sestamibi imaging before revascularization. Revascularization was performed irrespective of any viability data. Follow-up angiography was obtained 4.8 +/- 2.5 months after revascularization. RESULTS: Viability analysis was performed in 34 patients with patent target vessel at follow-up, of whom 9 (27%) exhibited functional recovery on left ventricular angiography. For dobutamine echocardiography, improvement of >/=2 adjacent akinetic segments resulted in improved sensitivity of 89% and specificity of 80% to predict functional recovery. For glucose metabolism, FDG uptake >55% was an optimal threshold yielding a sensitivity of 89% and a specificity of 68%. With respect to perfusion, (99m)Tc sestamibi uptake >60% was the best cutoff resulting in a sensitivity and a specificity of 56 and 88%, respectively. A concordant match of FDG >55% and of (99m)Tc sestamibi >50% resulted in optimized sensitivity (78%) and specificity (80%) with dual imaging. CONCLUSIONS: Recovery of chronically dysfunctional myocardium can be predicted with high accuracy by stimulation of contractile reserve or by concordant match of preserved glucose metabolism and residual perfusion.

Assessment of nicorandil therapy in ischemic myocardial injury by using contrast-enhanced and functional MR imaging.

PURPOSE: To determine the potential of mesoporphyrin- and gadopentetate dimeglumine-enhanced and functional magnetic resonance (MR) imaging in the assessment of the acute effect of nicorandil on ischemic injury of the myocardium. MATERIALS AND METHODS: Spin-echo MR imaging was used to monitor changes in myocardial contrast and function in reperfused myocardial injury. Inversion-recovery echo-planar MR imaging was used to depict the injured region. Myocardial injury in rats was produced by using 30 minutes of coronary occlusion followed by 24 hours reperfusion. Nicorandil (n = 9) was infused during occlusion and early reperfusion. Control animals (n = 11) received no therapy. At 24 hours, after administration of mesoporphyrin and gadopentetate dimeglumine and histochemical staining, the function and size of the injured region of the left ventricle (LV) were determined. A t test was used to compare data between groups of animals, whereas regression and Bland-Altman analyses were used to determine correlation and agreement between MR imaging and histomorphometry, respectively. RESULTS: Treated animals showed reduced infarction size as compared with the control group from 25.6% +/- 7.9 (SD) to 7.9% +/- 6.8 of LV myocardial area (P < .001), as defined with mesoporphyrin-enhanced MR imaging; while the size of the rim increased from 10.8% +/- 10.0 to 16.1% +/- 14.4 (P < .05). The diastolic-midventricular cavity area was smaller in treated animals (15.2 mm(2) +/- 4.3) compared with the control group (28.5 mm(2) +/- 7.9; P < .001). At functional MR imaging, nicorandil improved systolic reduction in LV cavity area (57.5% +/- 17.3) compared with the control group (38.0% +/- 16.0; P < .05) and preserved regional LV wall thickening at the site of injury (12.2% +/- 11.1 in treated group vs 0.3% +/- 8.6 in the control group; P < .05). CONCLUSION: Contrast material-enhanced MR imaging has the potential to demonstrate reduction in size of ischemically injured myocardium, whereas functional MR imaging demonstrated the recovery of LV function 24 hours after nicorandil therapy.

Coronary sinus flow measurement by means of velocity-encoded cine MR imaging: validation by using flow probes in dogs.

PURPOSE: To validate coronary sinus flow measurements for quantification of global left ventricular (LV) perfusion by means of velocity-encoded cine (VEC) magnetic resonance (MR) imaging and flow probes. MATERIALS AND METHODS: Measurements of coronary sinus flow were performed in seven dogs by using VEC MR imaging at baseline, single coronary arterial stenosis, dipyridamole stress, and reactive hyperemia. These measurements were compared with flow probe measurements of coronary blood flow (CBF) in the left anterior descending coronary (LAD) and circumflex (CFX) arteries (CBF(LAD+CFX)) and coronary sinus. LV blood perfusion was calculated in milliliters per minute per gram from coronary sinus flow, and LV mass was obtained by using VEC and cine MR imaging. LV mass was validated at autopsy. RESULTS: CBF(LAD+CFX) and coronary sinus flow at VEC MR imaging showed close correlation (r = 0.98, P: <.001). The difference between CBF(LAD+CFX) and MR coronary sinus flow was 3.1 mL/min +/- 8.5 (SD). LV mass at cine MR imaging was not significantly different from that at autopsy (73.2 g +/- 12.8 vs 69. 4 g +/- 12.8). At baseline, myocardial perfusion was 0.40 mL/min/g +/- 0.09 at VEC MR imaging, and CBF(LAD+CFX) was 0.44 mL/min/g +/- 0. 08 (not significant). Reactive hyperemia resulted in 2.7- and 2. 3-fold increases in coronary sinus flow at VEC MR imaging and flow probe CBF(LAD+CFX), respectively. CONCLUSION: VEC MR imaging has the potential to measure coronary sinus flow during different physiologic conditions and can serve as a noninvasive modality to quantify global LV perfusion in patients.

Impact of intravascular ultrasound guidance on directional coronary atherectomy.

In contrast to the luminogram of coronary angiography, intravascular ultrasound (IVUS) has proven to accurately assess both coronary lumen and vessel morphology due to its 360 degrees imaging capacity. Directional coronary atherectomy (DCA) improves the coronary lumen by removing plaque mass rather than stretching the vessel and compressing the plaque as with conventional percutaneous transluminal coronary angioplasty. In an attempt to optimize the procedural result of DCA we prospectively investigated the impact of IVUS guidance in a head to head comparison to on-line quantitative coronary angiography (QCA) on the result of DCA. In 16 consecutive patients IVUS demonstrated significant residual plaque mass after DCA irrespective of a satisfactory angiographic result. After a mean of 9 +/- 2 cuts luminal improvement was obtained with an area stenosis by angiography of 39 +/- 17% and by IVUS of 50 +/- 10% (p < 0.05), a diameter stenosis by angiography of 23 +/- 10% and IVUS of 35 +/- 14% (p < 0.05) and finally a minimal lumen diameter (MLD) by angiography of 2.9 +/- 0.5 mm and by IVUS of 2.3 +/- 0.5 mm (p < 0.005). After both on-line QCA and IVUS measurements a second series of 7 +/- 2 cuts were initiated to debulk more atheroma and improve stenosis dimensions. After additional cuts IVUS revealed further luminal improvement with an area stenosis by angiography of 25 +/- 16% and IVUS of 21 +/- 18% (n.s.), a diameter stenosis by angiography of 16 +/- 11% and by IVUS of 13 +/- 19% (n.s.) and finally a MLD by angiography of 3.1 +/- 0.5 mm and by IVUS of 2.8 +/- 0.3 mm (p < 0.05). Intraprocedural use of IVUS is superior to on-line QCA to assess the immediate result of DCA. IVUS-guided DCA results in more effective atheroma debulking than luminographic evaluation. Results of larger follow-up studies are needed to substantiate the intraprocedural advantage of IVUS with DCA.

Coronary flow reserve: assessment by magnetic resonance imaging.

Coronary angiography has been the standard method for quantifying the severity of coronary artery stenosis, however its physiological relevance by angiography is imperfect. At present velocity-encoded cine phase contrast MRI is a non invasive technique that can provide accurate assessment of coronary flow volume and coronary flow reserve, validated in animal and human studies by Doppler flow measurement. MRI may be recognized as a comprehensive, widely available technique independent of any nuclear tracer or contrast media, for evaluation of the presence and physiological significance of a variety of heart diseases which compromise coronary flow reserve.