Biases in the Assessment of Left Ventricular Function by Compressed Sensing Cardiovascular Cine MRI

PURPOSE: We investigate biases in the assessments of left ventricular function (LVF), by compressed sensing (CS)-cine magnetic resonance imaging (MRI). MATERIALS AND METHODS: Cardiovascular cine images with short axis view, were obtained for 8 volunteers without CS. LVFs were assessed with subsampled data, with compression factors (CF) of 2, 3, 4, and 8. A semi-automatic segmentation program was used, for the assessment. The assessments by 3 CS methods (ITSC, FOCUSS, and view sharing (VS)), were compared to those without CS. Bland-Altman analysis and paired t-test were used, for comparison. In addition, real-time CS-cine imaging was also performed, with CF of 2, 3, 4, and 8 for the same volunteers. Assessments of LVF were similarly made, for CS data. A fixed compensation technique is suggested, to reduce the bias. RESULTS: The assessment of LVF by CS-cine, includes bias and random noise. Bias appeared much larger than random noise. Median of end-diastolic volume (EDV) with CS-cine (ITSC or FOCUSS) appeared −1.4% to −7.1% smaller, compared to that of standard cine, depending on CF from (2 to 8). End-systolic volume (ESV) appeared +1.6% to +14.3% larger, stroke volume (SV), −2.4% to −16.4% smaller, and ejection fraction (EF), −1.1% to −9.2% smaller, with P < 0.05. Bias was reduced from −5.6% to −1.8% for EF, by compensation applied to real-time CS-cine (CF = 8). CONCLUSION: Loss of temporal resolution by adopting missing data from nearby cardiac frames, causes an underestimation for EDV, and an overestimation for ESV, resulting in underestimations for SV and EF. The bias is not random. Thus it should be removed or reduced for better diagnosis. A fixed compensation is suggested, to reduce bias in the assessment of LVF.

Cerebrospinal Fluid Dynamics in Patients with Multiple Sclerosis: The Role of Phase-Contrast MRI in the Differential Diagnosis of Active and Chronic Disease

OBJECTIVE: Multiple sclerosis (MS) is an inflammatory disease characterized by demyelinating plaques in the white matter. Chronic cerebrospinal venous insufficiency (CCSVI) has been proposed as a new hypothesis for the etiopathogenesis of MS disease. MS-CCSVI includes a significant decrease of cerebrospinal fluid (CSF) flow through the cerebral aqueduct secondary to an impaired venous outflow from the central nervous system. This study aimed to determine whether CSF flow dynamics are affected in MS patients and the contributions to differential diagnosis in active and chronic disease using phase-contrast magnetic resonance imaging (PC-MRI). MATERIALS AND METHODS: We studied 16 MS patients with chronic plaques (group 1), 16 MS patients with active plaques-enhanced on MRI (group 2), and 16 healthy controls (group 3). Quantitatively evaluation of the CSF flow was performed from the level of the cerebral aqueduct by PC-MRI. According to heart rates, 14–30 images were obtained in a cardiac cycle. Cardiac triggering was performed prospectively using finger plethysmography. RESULTS: No statistically significant difference was found between the groups regarding average velocity, net forward volume and the average flow (p > 0.05). Compared with the controls, group 1 and group 2, showed a higher peak velocity (5.5 ± 1.4, 4.9 ± 1.0, and 4.3 ± 1.3 cm/sec, respectively; p = 0.040), aqueductal area (5.0 ± 1.3, 4.1 ± 1.5, and 3.1 ± 1.2 mm2, respectively; p = 0.002), forward volume (0.039 ± 0.016, 0.031 ± 0.013, and 0.021 ± 0.010 mL, respectively; p = 0.002) and reverse volume (0.027 ± 0.016, 0.018 ± 0.009, and 0.012 ± 0.006 mL, respectively; p = 0.000). There were no statistical significance between the MS patients with chronic plaques and active plaques except for reverse volume. The MS patients with chronic plaques showed a significantly higher reverse volume (p = 0.000). CONCLUSION: This study indicated that CSF flow is affected in MS patients, contrary to the hypothesis that CCSVI-induced CSF flow decreases in MS patients. These findings may be explained by atrophy-dependent ventricular dilatation, which may occur at every stage of MS.

Analysis of speech and tongue motion in normal and post-glossectomy speaker using cine MRI

ABSTRACT Objective Since the tongue is the oral structure responsible for mastication, pronunciation, and swallowing functions, patients who undergo glossectomy can be affected in various aspects of these functions. The vowel /i/ uses the tongue shape, whereas /u/ uses tongue and lip shapes. The purpose of this study is to investigate the morphological changes of the tongue and the adaptation of pronunciation using cine MRI for speech of patients who undergo glossectomy. Material and Methods Twenty-three controls (11 males and 12 females) and 13 patients (eight males and five females) volunteered to participate in the experiment. The patients underwent glossectomy surgery for T1 or T2 lateral lingual tumors. The speech tasks “a souk” and “a geese” were spoken by all subjects providing data for the vowels /u/ and /i/. Cine MRI and speech acoustics were recorded and measured to compare the changes in the tongue with vowel acoustics after surgery. 2D measurements were made of the interlip distance, tongue-palate distance, tongue position (anterior-posterior and superior-inferior), tongue height on the left and right sides, and pharynx size. Vowel formants Fl, F2, and F3 were measured. Results The patients had significantly lower F2/Fl ratios (F=5.911, p=0.018), and lower F3/F1 ratios that approached significance. This was seen primarily in the /u/ data. Patients had flatter tongue shapes than controls with a greater effect seen in /u/ than /i/. Conclusion The patients showed complex adaptation motion in order to preserve the acoustic integrity of the vowels, and the tongue modified cavity size relationships to maintain the value of the formant frequencies.

Fast Cardiac CINE MRI by Iterative Truncation of Small Transformed Coefficients

PURPOSE: A new compressed sensing technique by iterative truncation of small transformed coefficients (ITSC) is proposed for fast cardiac CINE MRI. MATERIALS AND METHODS: The proposed reconstruction is composed of two processes: truncation of the small transformed coefficients in the r-f domain, and restoration of the measured data in the k-t domain. The two processes are sequentially applied iteratively until the reconstructed images converge, with the assumption that the cardiac CINE images are inherently sparse in the r-f domain. A novel sampling strategy to reduce the normalized mean square error of the reconstructed images is proposed. RESULTS: The technique shows the least normalized mean square error among the four methods under comparison (zero filling, view sharing, k-t FOCUSS, and ITSC). Application of ITSC for multi-slice cardiac CINE imaging was tested with the number of slices of 2 to 8 in a single breath-hold, to demonstrate the clinical usefulness of the technique. CONCLUSIONS: Reconstructed images with the compression factors of 3-4 appear very close to the images without compression. Furthermore the proposed algorithm is computationally efficient and is stable without using matrix inversion during the reconstruction.

Clinical Significance of Preoperative Cine Magnetic Resonance Study in Communicating Hydrocephalus

OBJECTIVE: To evaluate the changes of intracranial cerebrospinal fluid(CSF) dynamics in communicating hydrocephalus, the authors present an analysis of various parameters of cine magnetic resonance(MR) CSF flow images in case of progressive communicating hydrocephalus. METHODS: The MR images were obtained with 1.5T(GE Signa, GE Medical Systems, Milwaukee, USA) unit using the 2 dimensional cine phase contrast sequence with cardiac gating and gradient recalled echo imaging in 10 communicating hydrocephalus and 10 controls. Various parameters of the aqueduct and cervicomedullary subarachnoid space were plotted as wave forms. The wave forms were analyzed for configurations, amplitude parameters(Vmax, Vmin, Vdif), and temporal parameters(R-MSV, R-D, R-MDV, R-S). The statistical significance of each parameter examined with paired t-test. RESULTS: Distinct reproducible configuration features were obtained at both ROIs. We could determine the statistically significant differences between control and communicating hydrocephalus in temporal parameters at the aqueduct level. There was no significant differences at the cervicomedullary subarachnoid space level. In communicating hydrocephalus, the graph showed R-MDV(p=0.005) and R-S(p=0.001) shortening at the aqueduct. CONCLUSION: The analysis of cine MR CSF flow study may be helpful for diagnosing the communicating hydrocephalus and even deciding the necessity of shunting procedures. The temporal parameters are more important than amplitude parameters for diagnosing communicating hydrocephalus.

Treatment of Syringomyelia with Consideration on its Pathophysiology

The authors present a case of syringomyelia with postlaminectmy kyphosis. Twenty six year-old male, who received a operation 11 years ago for intradural cervical schwannoma. The patient visited our hospital for the evaluation of the quadripresis of recent onset. Preoperative magnetic resonance(MR) images revealed syringomyelia from C2 to T2. With phase contrast Cine MR image, cerebrospinal fluid dynamics were evaluated preoperatively and after surgical correction of kyphosis. The authors present the pathophysiology of syringomyelia and the selection of surgical procedure on basis of cerebrospinal fluid dynamics of syringomyelia.

Treatment of Syringomyelia with Consideration on its Pathophysiology

The authors present a case of syringomyelia with postlaminectmy kyphosis. Twenty six year-old male, who received a operation 11 years ago for intradural cervical schwannoma. The patient visited our hospital for the evaluation of the quadripresis of recent onset. Preoperative magnetic resonance(MR) images revealed syringomyelia from C2 to T2. With phase contrast Cine MR image, cerebrospinal fluid dynamics were evaluated preoperatively and after surgical correction of kyphosis. The authors present the pathophysiology of syringomyelia and the selection of surgical procedure on basis of cerebrospinal fluid dynamics of syringomyelia.

Comparison of Left and Right Ventricular Volume and Cardiac Output by MRI and Echocardiography

PURPOSE: Ventricular volume and cardiac output are very important to evaluate cardiac fuction. Cine MRI has been found to a feasible technique in evaluating cardiac anatomy and cardiovascular function in a variety of cardiac disease. Measurement of left ventricular volume by cine MRI was closely correlated with the result by echocardiography or cine angiography. The purpose of this study is to compare the left and right ventricular function and cardiac output by cine MRI with the data obtained by echocardiography to varify the utility of the cine MRI in assessment of cardiac function in newborns. METHODS: Ventricular volume and cardiac output were measurd by MRI on 51 newborns and were compared with those measured by two dimensional echocardiography on the same day. RESULTS: 1) Values for left ventricular volumes and cardiac output obtained with cine MRI correlated well with those obtained with echocardiography (left ventricular end-diastolic volume, r=0.953 ; left ventricular end-systolic volume, r=0.819 ; left ventricular cardiac output, r=0.920). 2) The correlation of right ventricular volumes or cardiac output by both two techniques was not so good as for the left ventricle, but showed satisfactory correlation (right ventricular end-diastolic volume, r=0.898 ; right ventricular end-systolic volume, r= 0.710 ; right ventricular cardiac output, r=0.650). CONCLUSIONS: MRI gives reliable values for the left and right ventricular volumes and cardiac output in newborn in addition to provide a superior cardiac antomy.

Comparison of Cine Magnetic Resonance Imaging with Doppler Echocardiography for the Quantative Evaluation of Tricuspid Regurgitation in Newborn

BACKGROUND: Cine MR imaging has been found to bo a non-invasive technique in evaluation cardiac anatomy and cardiovascular function in a variety of cardiac diseases. The capability of this technique for quantatively estimating the severity of regurgitation has not been tested in newborns. The purpose of this study is to compare the degees of tricuspid regurgitation by echorcardiography with those by cine MRI, and verify the utility of MRi in evaluating tricuspid regurgitation. METHODS: Fifty-one newborns with tricuspid regurgitation were evaluated on the same day by echocardiography and cine MRI. Area and regurgitant fraction of area were estimated at four chamber view by two techniques. RESULTS: The area of tricuspid regurgitation was similar by two techniques. The correlation for the area(r=0.66, p<0.025) and the regurgitant area fraction(r=0.647, p<0.025) of tricuspid regurgitation obained by cine MRI with echocardiographic data was good. CONCLUSION: Cine MR imaging can provide quantative data estimating for evaluation of tricuspid regurgitation in newborns.