Identifying and reverting the adverse effects of white matter hyperintensities on cortical surface analyses

The Human Connectome Project (HCP)-style surface-based brain MRI analysis is a powerful technique that allows precise mapping of the cerebral cortex. However, the strength of its surface-based analysis has not yet been tested in the older population that often presents with white matter hyperintensities (WMHs) on T2-weighted (T2w) MRI (hypointensities on T1w MRI). We investigated T1-weighted (T1w) and T2w structural MRI in 43 healthy middle-aged to old participants. Juxtacortical WMHs were often misclassified by the default HCP pipeline as parts of the gray matter in T1w MRI, leading to incorrect estimation of the cortical surfaces and cortical metrics. To revert the adverse effects of juxtacortical WMHs, we incorporated the Brain Intensity AbNormality Classification Algorithm into the HCP pipeline (proposed pipeline). Blinded radiologists performed stereological quality control (QC) and found a decrease in the estimation errors in the proposed pipeline. The superior performance of the proposed pipeline was confirmed using an originally-developed automated surface QC based on a large database. Here we showed the detrimental effects of juxtacortical WMHs for estimating cortical surfaces and related metrics and proposed a possible solution for this problem. The present knowledge and methodology should help researchers identify adequate cortical surface biomarkers for aging and age-related neuropsychiatric disorders.

GABA, glutamate and excitatory-inhibitory ratios measured using short-TE STEAM MRS at 7-Tesla: Effects of macromolecule basis sets and baseline parameters

Rationale and objectives

Macromolecules (MMs) affect the precision and accuracy of neurochemical quantification in magnetic resonance spectroscopy. A measured MM basis is increasingly used in LCModel analysis combined with a spline baseline, whose stiffness is controlled by a parameter named DKNTMN. The effects of measured MM basis and DKNTMN were investigated.

Materials and methods

Twenty-six healthy subjects were prospectively enrolled and scanned twice using a short echo-time Stimulated Echo Acquisition Mode (STEAM) at 7-T. Using LCModel, analyses were conducted using the simulated MM basis (MMsim) with DKNTMN 0.15 and an MM basis measured inhouse (MMmeas) with DKNTMN of 0.15, 0.30, 0.60 and 1.00. Cramér-Rao lower bound (CRLB) and the concentrations of gamma-aminobutyric acid (GABA), glutamate and excitatory-inhibitory ratio (EIR), in addition to MMs were statistically analyzed. Measurement stability was evaluated using coefficient of variation (CV).

Results

CRLBs of GABA were significantly lower when using MMsim than MMmeas; those of glutamate were 2-3. GABA concentrations were significantly higher in the analysis using MMsim than MMmeas where concentrations were significantly higher with DKNTMN of 0.15 or 0.30 than 0.60 or 1.00. Difference in glutamate concentration was not significant. EIRs showed the same difference as in GABA depending on the DKNTMN values. CVs between test-retest scans were relatively stable for glutamate but became larger as DKNTMN increased for GABA and EIR.

Conclusion

Neurochemical quantification depends on the parameters of the basis sets used for fitting. Analysis using MMmeas with DKNTMN of 0.30 conformed best to previous studies and is recommended.

Neuroimaging at 7 Tesla: a pictorial narrative review

Neuroimaging using the 7-Tesla (7T) human magnetic resonance (MR) system is rapidly gaining popularity after being approved for clinical use in the European Union and the USA. This trend is the same for functional MR imaging (MRI). The primary advantages of 7T over lower magnetic fields are its higher signal-to-noise and contrast-to-noise ratios, which provide high-resolution acquisitions and better contrast, making it easier to detect lesions and structural changes in brain disorders. Another advantage is the capability to measure a greater number of neurochemicals by virtue of the increased spectral resolution. Many structural and functional studies using 7T have been conducted to visualize details in the white matter and layers of the cortex and hippocampus, the subnucleus or regions of the putamen, the globus pallidus, thalamus and substantia nigra, and in small structures, such as the subthalamic nucleus, habenula, perforating arteries, and the perivascular space, that are difficult to observe at lower magnetic field strengths. The target disorders for 7T neuroimaging range from tumoral diseases to vascular, neurodegenerative, and psychiatric disorders, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy, major depressive disorder, and schizophrenia. MR spectroscopy has also been used for research because of its increased chemical shift that separates overlapping peaks and resolves neurochemicals more effectively at 7T than a lower magnetic field. This paper presents a narrative review of these topics and an illustrative presentation of images obtained at 7T. We expect 7T neuroimaging to provide a new imaging biomarker of various brain disorders.

Trans-stenotic pressure gradient as derived from CT improves patient management: ADVANCE registry

Background

The change in fractional flow reserve derived from CT (FFRCT) value across a coronary stenosis (ΔFFRCT) improves the physiological characterization of coronary artery disease (CAD). The role of ΔFFRCT in guiding risk-stratification and downstream testing in patients with stable CAD is unknown.

Purpose

To investigate the incremental value of ΔFFRCT at predicting early revascularization and improving efficacy of resource utilization.

Methods

Patients with CAD on CT coronary angiography (CTCA) were enrolled in an international multicenter registry. Patients with non-evaluable FFRCT analysis were excluded. The CTCA was assessed for: stenosis severity as per CAD-Reporting and Data System (CAD-RADS), lesion length and lesion-specific FFRCT measured 2 cm distal to stenosis. Risk factors and actual treatment (revascularization vs medical therapy) at 90-day follow-up were recorded. Multivariable logistic regression analysis for early revascularization was conducted. The incremental discrimination for revascularization prediction was compared among 3 models (model 1: risk factors + lesion length and location + CAD-RADS; model 2: model 1 + lesion-specific FFRCT; model 3: model 2 + ΔFFRCT). Simulating ICA referral for patients with CAD-RADS ≥3 and lesion-specific FFRCT ≤0.8, the potential impact of ΔFFRCT at reducing ICA referral and improving the ratio of subsequent revascularization was assessed.

Results

Of 4730 patients (66±10 years; 34% female), 2092 (42.7%) underwent ICA and 1168 (24.7%) underwent early revascularization. With increasing ΔFFRCT, a higher incidence of revascularization (Figure 1A) and an increase in the revascularization to ICA ratio was observed (Figure 1B). ΔFFRCT >0.13 was the optimal cut-off for predicting revascularization as determined by the Youden index. ΔFFRCT remained an independent predictor for early revascularization (odds ratio per 0.05 increase with 95% CI, 1.31 [1.26–1.35]; p<0.0001) after adjusting for risk factors, CAD-RADS, lesion length and location, and FFRCT. Among the 3 models, model 3, which included ΔFFRCT showed the highest AUC and improved discrimination power compared to model 2 (0.87 [0.86–0.88] vs 0.85 [0.84–0.86]; p<0.0001] (Figure 2), with the greatest incremental value for ΔFFRCT observed in patients with lesion-specific FFRCT between 0.71–0.80. In patients with CAD-RADS ≥3 and lesion-specific FFRCT ≤0.8, a diagnostic strategy incorporating ΔFFRCT >0.13 would potentially reduce ICA referral by 32.2% (1638 to 1110) and improve the revascularization to ICA ratio from 65.2% [1068/1638] to 73.1% [811/1110].

Conclusions

The characterization of CAD with ΔFFRCT improves the identification of patients requiring early revascularization as compared to a standard diagnostic strategy of CTCA with FFRCT, particularly for those with lesion-specific FFRCT of 0.71–0.80. ΔFFRCT has the potential to aid decision making for ICA referral and improve the efficiency of resource utilization.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): HeartFlow, Inc., Redwood City, CA, USA ΔFFRCT and actual treatmentROC curve for early revascularization

Impact of transcatheter aortic valve implantation on coronary flow reserve by transthoracic Doppler echocardiography 1-year after the intervention in severe aortic stenosis patients

Background

Coronary flow reserve (CFR) which is one of indexes reflecting coronary microcirculation in patients without significant epicardial coronary lesions can be impaired in patients with severe aortic stenosis (AS). It has been shown that CFR is an independent predictor for future cardiovascular events in AS patients. Transcatheter aortic valve implantation (TAVI) has rapidly become widespread and is becoming the standard treatment for severe AS. This procedure may have a good effect on CFR due to reduction of severe afterload in patients with severe AS. Although the recent reports evaluated change in CFR immediately and 6 months after TAVI, it has not been evaluated whether impaired CFR improves 1-year after TAVI in AS patients with preserved left ventricular ejection fraction (LVEF).

Purpose

The purpose of the present study was to investigate whether impaired CFR improves 1-year after TAVI in severe AS patients with preserved LVEF.

Methods

The study population consists of consecutive 105 patients with severe AS undergoing TAVI. Exclusion criteria were atrial fibrillation, old myocardial infarction, history of coronary artery bypass grafting, significant lesions in the left anterior descending artery (LAD), moderate or severe mitral valve disease, history of valve replacement, LVEF <50% and preoperative CFR >2.2. CFR was obtained from coronary flow velocity by transthoracic echocardiography at rest and maximal hyperemia in LAD before, immediately and 1-year after TAVI. We compared CFR between before and after TAVI in the study patients who did not meet the exclusion criteria.

Results

After exclusion of 76 patients who met the exclusion criteria, the final study patients consist of 29 patients (8 male, 84.9±5.2 years). There was no significant difference in LVEF (61.3±3.4% vs 61.6±4.4%, P=0.667) and LV end-diastolic volume (LVEDVI; 58.2±9.2 mL/m2 vs 55.8±9.0 mL/m2, P=0.089) between before and immediately after TAVI. LVEF (61.0±2.8%, P=0.721) and LVEDVI (58.0±9.1 mL/m2, P=0.949) 1-year after TAVI were similar to those before TAVI. There was no significant difference in coronary flow velocity at rest between before and immediately after TAVI (27.4±8.9 vs 24.4±7.0 cm/s, P=0.051) and between before and 1-year after TAVI (25.9±8.3 cm/s, P=0.396). Coronary flow velocity at maximal hyperemia 1-year after TAVI significantly increased compared with that before TAVI (from 48.8±13.9 to 67.9±21.0 cm/s, P<0.001) while there was no significant difference between before and immediately after TAVI (52.0±12.0 cm/s, P=0.186). Impaired CFR before TAVI (1.82±0.28) increased immediately (2.03±0.39, P=0.009) and 1-year after TAVI (2.69±0.57, P<0.001).

Conclusions

The present results suggest that impaired CFR in patients with preserved LVEF improves 1-year after TAVI. TAVI may have a good effect on CFR in severe AS patients with preserved LVEF.

Funding Acknowledgement

Type of funding sources: None.

Temporal subtraction CT with nonrigid image registration improves detection of bone metastases by radiologists: results of a large-scale observer study

To determine whether temporal subtraction (TS) CT obtained with non-rigid image registration improves detection of various bone metastases during serial clinical follow-up examinations by numerous radiologists. Six board-certified radiologists retrospectively scrutinized CT images for patients with history of malignancy sequentially. These radiologists selected 50 positive and 50 negative subjects with and without bone metastases, respectively. Furthermore, for each subject, they selected a pair of previous and current CT images satisfying predefined criteria by consensus. Previous images were non-rigidly transformed to match current images and subtracted from current images to automatically generate TS images. Subsequently, 18 radiologists independently interpreted the 100 CT image pairs to identify bone metastases, both without and with TS images, with each interpretation separated from the other by an interval of at least 30 days. Jackknife free-response receiver operating characteristics (JAFROC) analysis was conducted to assess observer performance. Compared with interpretation without TS images, interpretation with TS images was associated with a significantly higher mean figure of merit (0.710 vs. 0.658; JAFROC analysis, P = 0.0027). Mean sensitivity at lesion-based was significantly higher for interpretation with TS compared with that without TS (46.1% vs. 33.9%; P = 0.003). Mean false positive count per subject was also significantly higher for interpretation with TS than for that without TS (0.28 vs. 0.15; P < 0.001). At the subject-based, mean sensitivity was significantly higher for interpretation with TS images than that without TS images (73.2% vs. 65.4%; P = 0.003). There was no significant difference in mean specificity (0.93 vs. 0.95; P = 0.083). TS significantly improved overall performance in the detection of various bone metastases.

Diagnostic Accuracy of Diastolic Fractional Flow Reserve for Functional Evaluation of Coronary Stenosis

Background

In the resting conditions, narrowing the window of coronary pressure measurements from the whole cardiac cycle to diastole improves diagnostic performance of coronary pressure–derived physiological index. However, whether this also applies to the hyperemic conditions has not yet been thoroughly evaluated.

Objectives

The purpose of this study was to assess whether diastolic fractional flow reserve (diastolic FFR) has better diagnostic performance in identifying ischemia-causing coronary lesions than conventional FFR in a prospective, multicenter, and independent core laboratory–based environment.

Methods

In this prospective multicenter registry at 29 Japanese centers, we compared the diagnostic performance of FFR, diastolic FFR, resting distal to aortic coronary pressure (Pd/Pa), and diastolic pressure ratio (dPR) using myocardial perfusion scintigraphy (MPS) as the reference standard in 378 patients with single-vessel coronary disease.

Results

Inducible myocardial ischemia was found on MPS in the relevant myocardial territory of the target vessel in 85 patients (22%). In the receiver-operating curve analyses, diastolic FFR had comparable area under the curve (AUC) compared with FFR (AUC_{diastolic FFR}: 0.66; 95% confidence interval [CI]: 0.58-0.73, vs AUC_FFR: 0.66; 95% CI: 0.58-0.74, P = 0.624). FFR and diastolic FFR showed significantly larger AUCs than resting Pd/Pa (0.62; 95% CI: 0.54-0.70; P = 0.033 and P = 0.046) but did not show significantly larger AUCs than dPR (0.62; 95% CI: 0.55-0.70; P = 0.102 and P = 0.113).

Conclusions

Diastolic FFR showed a similar diagnostic performance to FFR as compared with MPS. This result reaffirms the use of FFR as the most accurate invasive physiological lesion assessment. (Diagnostic accuracy of diastolic fractional flow reserve (d-FFR) for functional evaluation of coronary stenosis; UMIN000015906)

Safety for Human MR Scanners at 7T

After introduction of the first human 7 tesla (7T) system in 1999, 7T MR systems have been employed as one of the most advanced platforms for human MR research for more than 20 years. Currently, two 7T MR models are approved for clinical use in the U.S.A. The approval facilitated introduction of the 7T system, summing up to around 100 worldwide. The approval in Japan is much awaited. As a clinical MR scanner, the 7T MR system is drawing attention in terms of safety.Several large-sized studies on bioeffects have been reported for vertigo, dizziness, motion disturbances, nausea, and others. Such effects might also be found in MR workers and researchers. Frequency and severity of reported bioeffects will be presented and discussed, including their variances. The high resonance frequency and shorter RF wavelength of 7T increase the concern about the safety. Homogeneous RF pulse excitation is difficult even for the brain, and a multi-channel parallel transmit (pTx) system is considered mandatory. However, pTx may create a hot spot, which makes the estimation of specific absorption rate (SAR) to be difficult. The stronger magnetic field of 7T causes a large force of displacement and heating on metallic implants or devices, and the scan of patients with them should not be conducted at 7T. However, there are some opinions that such patients might be scanned even at 7T, if certain criteria are met. This article provides a brief review on the effect of the static magnetic field on humans (MR subjects, workers, and researchers) and neurons, in addition to scan sound, SAR, and metal implants and devices. Understanding and avoiding adverse effects will contribute to the reduction in safety risks and the prevention of incidents.

Automatic detection of acute ischemic stroke using non-contrast computed tomography and two-stage deep learning model

BACKGROUND AND OBJECTIVE

Currently, it is challenging to detect acute ischemic stroke (AIS)-related changes on computed tomography (CT) images. Therefore, we aimed to develop and evaluate an automatic AIS detection system involving a two-stage deep learning model.

METHODS

We included 238 cases from two different institutions. AIS-related findings were annotated on each of the 238 sets of head CT images by referring to head magnetic resonance imaging (MRI) images in which an MRI examination was performed within 24 h following the CT scan. These 238 annotated cases were divided into a training set including 189 cases and test set including 49 cases. Subsequently, a two-stage deep learning detection model was constructed from the training set using the You Only Look Once v3 model and Visual Geometry Group 16 classification model. Then, the two-stage model performed the AIS detection process in the test set. To assess the detection model's results, a board-certified radiologist also evaluated the test set head CT images with and without the aid of the detection model. The sensitivity of AIS detection and number of false positives were calculated for the evaluation of the test set detection results. The sensitivity of the radiologist with and without the software detection results was compared using the McNemar test. A p-value of less than 0.05 was considered statistically significant.

RESULTS

For the two-stage model and radiologist without and with the use of the software results, the sensitivity was 37.3%, 33.3%, and 41.3%, respectively, and the number of false positives per one case was 1.265, 0.327, and 0.388, respectively. On using the two-stage detection model's results, the board-certified radiologist's detection sensitivity significantly improved (p-value = 0.0313).

CONCLUSIONS

Our detection system involving the two-stage deep learning model significantly improved the radiologist's sensitivity in AIS detection.

Diagnostic accuracy of left ventricular diastolic transverse strain imaging by speckle tracking echocardiography for diagnosing chest pain in diabetic patients

Background

Two-dimensional speckle tracking echocardiography (2D-STE) has been reported to be useful for the diagnosis of myocardial ischemia by detecting delayed relaxation (diastolic stunning) after an episode of angina. 2D-longitudinal strain is not specific besides ischemia such as diastolic dysfunction, and diabetes have been associated with abnormal longitudinal fibers. The aim is to evaluate the diagnostic accuracy of Left ventricular (LV) diastolic transverse strain imaging by STE to detect the presence of acute coronary syndrome (ACS) in diabetic patients with acute chest pain.

Methods

385 consecutive patients with acute chest pain and without wall motion abnormality, who were admitted to an emergency department (ED) at 1 of 12 clinical sites in Japan, were enrolled and underwent 2D-STE at ED. Left ventricular (LV) transverse strain values at aortic valve closure (A) and one-third of diastole duration (B) were measured. The strain imaging diastolic index (SI-DI) was value was determined as: (A − B)/A × 100% to assess the LV diastolic strain imaging and was used to identify the regional LV delayed relaxation. All patients underwent coronary CT or coronary angiography to establish the diagnosis of ACS. Clinicians were blinded to the 2D-STE results.

Results

Out of 385 patients, 2D-STE analysis was possible in 365 patients (94%). 76 patients were diabetic (DM+), and 289 patients were non-diabetic (DM-). With assessment of coronary CT or coronary angiography, ACS was diagnosed in 125 patients (34%). 2D-STE was obtained at a mean of 5.3 hours after chest pain episode. Transverse SI-DI of ischemic segments were significantly lower than those of non-ischemic segments (p value &lt;0.001) in both diabetic and non-diabetic patients, and transverse SI-DI of both diabetic and non-diabetic patients demonstrated high area under curve (AUC) for detection of myocardial ischemia (Figure: RCA; right coronary artery, LAD; left anterior descending artery, LCX; left circumferencial artery). In diabetic patients, sensitivity, specificity, and negative predictive value for ACS of transverse SI-DI are 100%, 95%, 100% in RCA (a cut-off value of 36.2), and 86.4%, 95%, 93% in LAD (a cut-off value of 50.2), and 75%, 85%, 94% in LCX (a cut-off value of 52), respectively.

Conclusion

LV diastolic transverse strain imaging by 2D-STE at ED increase the sensitivity, specificity and accuracy to predict the presence of ACS in diabetic patients with chest pain, as well as non-diabetic patients. (UMIN000013859).

Figure 1. Transverse Strain (SI-DI): AUC (95% CI)

Funding Acknowledgement

Type of funding source: None

Delayed hyperenhancement obtained by non-contrast computed tomography following coronary angiography in patients of extracorporeal cardiopulmonary resuscitation

Background/Introduction

Extracorporeal cardiopulmonary resuscitation (ECPR) has been reported to improve survival and neurologic outcome as compared to conventional CPR in refractory cardiac arrest. Although prognostic factors of these patients have been reported, predicting of outcome is difficult in real world. Recently, early evaluation of myocardial viability in acute myocardial infarction by non-contrast computed tomography (CT) post coronary angiography (CAG) has been reported. And myocardial contrast delayed enhancement obtained by this method related to higher risk of cardiac events. However, few studies have reported delayed enhancement on left ventricular wall findings in non-contrast CT after CAG in terms of patients performed ECPR.

Purpose

To investigate the impact of delayed hyperenhancement obtained by non-contrast CT following CAG in patients performed ECPR.

Methods

We investigated 79 patients treated by ECPR for refractory cardiac arrest regardless of whether in-hospital or out-hospital in our institute from Apr 2009 to Feb 2018. Thirty-two in these patients received non-contrast CT following CAG with ECPR were enrolled. All ECPR cases underwent VA-ECMO in the catheter laboratory using percutaneous procedure while maintaining conventional CPR. Non-ECG-gated and non-contrast CT was performed using a 64-row multidetector CT scanner.

Results

Survival rate was 18.8% in this cohort. There was no significant difference between survive and in-hospital death group in terms of patient characteristics, clinical time courses, initial blood samples and procedure characteristics. Only delayed hyperenhancement showed significant difference between 2 groups (p=0.04). All delayed hyperenhancements were detected in only in-hospital death group. Delayed hyperenhancement was detected in 12 cases (37.5%). Initial shockable rhythm was less common in cases with delayed hyperenhancement. Cardiac death tended to be more frequent in patients with delayed hyperenhancement. The major causes of death were bleeding (41.7%) and heart failure (33%).

Conclusion(s)

Delayed hyperenhancement in patients treated ECPR was strong predictor of in-hospital death.

Image of delayed hyperenhancement

Funding Acknowledgement

Type of funding source: None

Bayesian Statistical Model of Item Response Theory in Observer Studies of Radiologists

RATIONALE AND OBJECTIVES

The purpose of this study was to validate a Bayesian statistical model of item response theory (IRT). IRT was used to evaluate a new modality (temporal subtraction, TS) in observer studies of radiologists, compared with a conventional modality (computed tomography).

MATERIALS AND METHODS

From previously published papers, we obtained two datasets of clinical observer studies of radiologists. Those studies used a multi-reader and multi-case paradigm to evaluate radiologists' detection abilities, primarily to determine if TS could enhance the detectability of bone metastasis or brain infarctions. We applied IRT to these studies' datasets using Stan software. Before applying IRT, the radiologists' responses were recorded as binaries for each case (1 = correct, 0 = incorrect). Effect of TS on detectability was evaluated by using our IRT model and calculating the 95% credible interval of the effect.

RESULTS

The mean, median, and 95% credible interval of the effect of TS were 0.913, 0.885, and 0.243-1.745 for the bone metastasis detection, and 2.524, 2.50, and 1.827-3.310, for the brain infarction detection. For both detection studies, the 95% credible intervals of the effect of TS did not include zero, indicating that TS significantly improved diagnostic ability.

CONCLUSION

Judgments based on the present study results were compatible with the two previous studies. Our study results demonstrated that the Bayesian statistical model of IRT could judge a new modality's usefulness.

P1518 Relationship between post-operative asymptomatic status and reverse remodeling of large left atrium in patients with aortic stenosis who underwent aortic valve replacement

Introduction

Recently, we have reported that large left atrial volume (minimum left atrial volume index : LAVImin ≥30ml/m²) at end-diastole determined by direct exposure of left ventricular (LV) end-diastolic pressure can predict post-operative symptomatic status after aortic valve replacement (AVR) in aortic stenosis (AS) patients with high sensitivity and modest specificity. Reverse remodeling of large LAVImin after AVR may contribute to false positive for the prediction of post-operative symptomatic status in patients with AS.

Purpose

The purpose of this study was to evaluate relationship between post-operative symptomatic status and reverse remodeling of large LAVImin in patients with AS who underwent AVR.

Methods

The study population consisted of 75 patients with AS who underwent AVR and were followed up for 600 days after AVR, after the exclusion of the followings; atrial fibrillation, significant coronary artery disease, significant mitral valve disease, pacemaker rhythm, and inadequate echocardiographic images. We measured LAVImin by biplane Simpson"s method before and after AVR. Preoperative large LAVImin (≥30ml/m²) according to the previous study was observed in 32 (43%) of 75 patients. We divided these 32 patients into two groups according to the post-operative symptomatic status during the follow-up period.

Results

There was no significant difference in pre-operative LAVImin between patients with and without post-operative symptom (46.5 ± 13.4 vs 40.4 ± 8.6 ml/m²). On the other hand, post-operative LAVImin in patients without post-operative symptom was significantly smaller than that in patients with post-operative symptom (31.5 ± 8.6 vs 54.8 ± 14.0 ml/m², p &lt; 0.01). While significant regression in LAVImin after AVR was observed in patients without post-operative symptom (40.4 ± 8.6 to 31.5 ± 8.6 ml/m², p &lt; 0.05), no regression in LAVImin after AVR was observed in patients with post-operative symptom (46.5 ± 13.4 to 54.8 ± 14.0 ml/m²).

Conclusions

Reverse remodeling of large LAVmin in patients with AS who underwent AVR was observed in post-operative asymptomatic group, but not in symptomatic group. These results suggest that reverse remodeling of large LAVImin after AVR could contribute to the post-operative asymptomatic status in patients with AS who underwent AVR.

P91 Prognostic value of tissue-tracking mitral annular displacement by speckle-tracking echocardiography in asymptomatic patients with aortic stenosis with preserved left ventricular ejection fraction

Background

  Management of asymptomatic severe aortic stenosis (AS) patients with preserved left ventricular (LV) ejection fraction (EF) remains controversial. Recent studies using have shown that decreased LV longitudinal deformation assessed by global longitudinal strain analysis can predict adverse cardiac events in AS patients with preserved EF. Tissue-tracking mitral annular displacement (TMAD) by speckle-tracking echocardiography provides rapid and simple assessment of LV longitudinal deformation even when the acoustic window is poor (Fig.1).

Purpose

 The purpose of this study was to examine the value of TMAD to predict occurrence of the cardiac events in asymptomatic severe AS patients with preserved EF.

Methods

  We studied 103 patients with severe AS and preserved EF [aortic velocity &gt;4m/s or aortic valve area (AVA) &lt;1.0 cm2, EF &gt;50%]in whom TMAD was measured, and a total of 44 patients were included in the final data setaccording to the exclusion criteria. Using TMAD analysis software, the base-to-apex displacement of automatically defined mid-point of mitral annular line in four-chamber view was quickly assessed, and the percentage of its displacement to LV length at end-diastole (%TMAD) was calculated (Fig.1). We investigated the association between %TMAD and the cardiac events including implementation of hospitalization due to heart failure, decreased EF (&lt; 50%), aortic valve replacement or transcatheter aortic valve implantation due to appearance of symptoms and cardiac death, 

Results

 In all the final study patients, %TMAD was successfully and quickly (within 10 seconds) evaluated. During a follow-up, the cardiac events developed in 16 (36%) of 44 patients. Tableshows echocardiographic parameters in patients with and without the cardiac events. %TMAD was significantly impaired in patients with the cardiac events compared with those without the cardiac events (9.6 ± 0.6 vs 12.1 ± 0.4%, p= 0.002). The other parameters were not involved in the event occurrence; age, LV mass index, EF, aortic velocity, AVA, tricuspid regurgitation pressure gradient (TR-PG), early diastolic /atrial filling velocity (E/A), early diastolic velocity of the mitral valve annulus (e’) and E/e’. In multiple variable analysis, %TMAD was an independentpredictor of the cardiac events (HR; 12.1, p= 0.001). ROC analysis revealed that the area under the curve of %TMAD was 0.81 for the cardiac events. Kaplan-Meier analysis showed %TMAD (cut-off: 11.9) provides a significant difference in the cardiac event (Fig. 2). Conclusions.  The present results suggests that TMAD easily and rapidly estimated by speckle-tracking echocardiography can be used as a simple method to predict occurrence of the cardiac events in asymptomatic severe AS patients with preserved EF.

Abstract P91 Figure 1,2 and Table

1225 Diagnostic accuracy of left ventricular diastolic strain imaging by speckle tracking echocardiography in detecting ischemic etiology of acute chest pain

Funding Acknowledgements

none

OnBehalf

A TRAC-SI Multicenter Trial

Background

Two-dimensional speckle tracking echocardiography (2D-STE) has been reported to be useful for the diagnosis of myocardial ischemia by detecting delay in regional myocardial expansion (diastolic stunning) up to many hours after an episode of angina. The aim is to evaluate the diagnostic accuracy of Left ventricular (LV) diastolic longitudinal, circumferential, transverse and radial strain imaging by STE to detect the presence of acute coronary syndrome (ACS) in patients with acute chest pain.

Methods

388 consecutive patients with acute chest pain and without wall motion abnormality, who were admitted to an emergency department (ED) at 1 of 12 clinical sites in Japan, were enrolled and underwent 2D-STE at ED. Left ventricular (LV) longitudinal, circumferential, transverse and radial strain values at aortic valve closure (A) and one-third of diastole duration (B) were measured. The strain imaging diastolic index (SI-DI) was value was determined as: (A-B)/A × 100% to assess the LV diastolic strain imaging and was used to identify the regional LV delayed relaxation. All patients underwent coronary CT or coronary angiography to establish the diagnosis of ACS. Clinicians were blinded to the 2D-STE results.

Results

Out of 388 patients, 2D-STE analysis was possible in 358 patients (92%). With assessment of coronary CT or coronary angiography, ACS was diagnosed in 118 patients (33%). 2D-STE was obtained at a mean of 5.3 hours after chest pain episode. SI-DI of longitudinal, circumferential, transverse and radial strain of ischemic segments were significantly lower than those of non-ischemic segments (p value &lt; 0.001), and transverse and radial SI-DI demonstrated high diagnostic accuracy, compared with longitudinal SI-DI (Figure 1). Sensitivity, specificity, and negative predictive value for ACS of transverse SI-DI are 87%, 88%, % and 95%, respectively, using a cut-off value of 63.3.

Conclusion

LV diastolic strain imaging by 2D-STE at ED increase the sensitivity, specificity and accuracy to predict the presence of ACS in patients with chest pain. Compared with longitudinal diastolic strain imaging, transverse diastolic strain imaging is more sensitive marker to detect the myocardial ischemic episode (UMIN000013859).

Abstract 1225 Figure 1

P1252Diagnostic performance of quantitative flow ratio from coronary angiography versus fractional flow reserve from computed tomography

Background

QFR and FFRCT are recently developed, less-invasive techniques for functional assessment of coronary artery disease.

Objectives

We compared the diagnostic performance between fractional flow reserve derived from computed tomography (FFRCT) and quantitative flow ratio (QFR) derived from coronary angiography, using FFR as the standard reference.

Methods

We measured FFRCT, QFR and FFR in 152 patients (233 vessels) with stable coronary artery disease.

Results

QFR was highly correlated with FFR (r=0.78, p<0.001), while FFRCT was moderately correlated with FFR (r=0.63, p<0.001). Both QFR and FFRCT showed good agreements with FFR, presenting small values of mean difference and root-mean-squared deviation (FFR -QFR: 0.02±0.09 and FFR -FFRCT: 0.03±0.11). The AUC of QFR was significantly greater than that of 3D-QCA-derived %DS (0.93 vs. 0.78; difference: 0.15; 95% CI: 0.09 to 0.20; p<0.001). The AUC of FFRCTwas significantly greater than that of CCTA-derived %DS (0.82 vs. 0.70; difference: 0.12; 95% CI: 0.05 to 0.19; p<0.001). The AUC of QFR was significantly greater than that of FFRCT (0.93 vs. 0.82; difference: 0.11; 95% CI: 0.05 to 0.16; p<0.001). The sensitivity, specificity, positive predictive value, and negative predictive valueof QFR ≤0.80 for predicting FFR ≤0.80 were 90%, 82%, 81%, and 90%, respectively. Those of FFRCT ≤0.80 for predicting FFR ≤0.80 were 82%, 70%, 70%, and 82%, respectively. The diagnostic accuracy of QFR ≤0.80 for predicting FFR ≤0.80 was 85% [95% confidence interval: 81% to 89%], while that of FFRCT≤0.80 for predicting FFR ≤0.80was 76% [95% confidence interval: 70% to 80%].

Figure 1. Comparison of FFR ≤0.80 predictors

Conclusions

Both QFR and FFRCTpossessed the ability to accurately evaluate the functional severity of coronary stenosis.

P2700Impact of instantaneous wave-free ratio on graft failure after coronary artery bypass graft surgery

Background

It has been reported that preoperative fractional flow reserve (FFR) is associated with graft patency after coronary artery bypass graft (CABG) and the patency is excellent when a bypass graft is anastomosed on a vessel with positive FFR. However, the association with graft patency has not yet been investigated in its novel counterpart, instantaneous wave-free ratio (iFR), and iFR sometimes contradicts FFR results.

Purpose

The purpose of this study is to assess an impact of preoperative iFR on a graft failure after CABG in patients with coronary arteries showing positive FFR (≤0.80).

Methods

We retrospectively identified patients who had undergone preoperative coronary angiography in conjunction with resting and hyperemic intra-coronary pressure measurements, CABG, and graft evaluation by coronary computed tomography angiography. After excluding vessels with negative FFR (>0.80), vessels were divided into two groups: negative iFR group (iFR >0.89) and positive iFR group (iFR ≤0.89). The rate of graft failure within 1 year after CABG was compared between the two groups.

Results

We analyzed 131 vessels in 89 patients (35 vessels in the negative iFR group and 96 vessels in the positive iFR group). The negative iFR group showed significantly higher iFR (0.92±0.02 vs. 0.74±0.13, P<0.0001) and FFR (0.72±0.06 vs. 0.63±0.09, P<0.0001) than the positive iFR group, although percent diameter stenosis (%DS) was comparable (57±10 vs. 56±9, P=0.47). The graft failure significantly often occurred in the negative iFR group than in the positive iFR group (28.6% vs. 8.3%, P=0.0029). In order to reduce the imbalance in the baseline characteristics except for iFR, 70 vessels were selected by using propensity score matching (n=35 in each group). The propensity score matched vessels also demonstrated significantly higher rate of graft failure in the negative iFR group than in the positive iFR group (28.6% vs. 5.7%, p=0.026) despite much more balanced FFR (0.72±0.06 vs. 0.69±0.07, p=0.02) and %DS (57±10 vs. 57±9, p=1.000).

Conclusions

Even when FFR is positive, the graft failure is likely to occur when a bypass graft is anastomosed on a vessel with negative iFR compared to a vessel with positive iFR.

Acknowledgement/Funding

None

P3576Histopathological validation of optical coherence tomography assessment for cholesterol crystals

Background

Cholesterol crystals (CCs) are well recognized as one of important components of advanced atherosclerotic plaques. Whilethe consensus document for intravascular optical coherence tomography (OCT) has proposed that CCs are appeared as thin, linear regions of high-signal intensity within a plaque, no study has validated CCs assessment by OCT in comparison with histopathology.

Purpose

Thepurpose of this study was to validate OCT assessments of CCs with histopathology.

Methods

A total of 27 diseased coronary artery samples (10–20 mm length) were resected from 7 randomly selected cadavers. OCT imaging was performed for the samples. Then, arterial samples were fixed in 10% formalin for ≥48 hours, decalcified and processed for standard paraffin embedding. Sections 5μm thick were sliced at the ink-marked imaging sites and stained with hematoxylin and eosin, and Masson's Trichrome. An independent pathologist blinded to the OCT results diagnosed all of the plaques. Subsequently, the OCT images were interpreted by an observer blinded to the histological results. In the OCT assessment, CCs were defined as thin, linear regions of high-signal intensity within a plaque.

Results

We obtained 27 pairs of OCT/ histopathology. CCs were diagnosed by histology in 10 (37%) of the 27 pairs. The sensitivity and specificity of OCT for detecting CCs were 60% and 94%, respectively.

Conclusion

OCT has a high specificity but modest sensitivity for detection of CCs in comparison with histopathology. CCs diagnosed with OCT would help the identification of advanced atherosclerotic plaques.

Acknowledgement/Funding

JSPS KAKENHI 17K09557

P3387Cholesterol crystals in superficial plaque layer detected by optical coherence tomography as a new morphological feature for plaque rupture

Background

While plaque rupture (PR) is the leading cause of acute myocardial infarction (AMI), other etiologies are also involved in the onset of AMI. Cholesterol crystals (CCs) are usually present abundantly in atherosclerotic plaques, especially in the culprit site of AMI. However, the relationship between in vivo CCs and PR is unclear. Optical coherence tomography (OCT) is a high-resolution imaging technique that allows for the in vivo identification of various plaque characteristics including PR and CCs.

Purpose

The aim of this study was to investigate prevalence and distribution of CCs between patients with AMI with PR, AMI without PR, and SAP.

Method

This study consisted of 146 patients with coronary artery disease (AMI with PR; n=64, AMI without PR; n=41, and SAP; n=41) who underwent OCT prior to percutaneous coronary intervention. Plaque characteristics in OCT images were assessed according to the consensus document. We classified the distribution of CCs as follows; superficial type CCs were defined by any of the CCs invading the fibrous cap and remaining CCs as deep type CCs.

Result

There was no statistical difference in clinical characteristics among the three groups. The % diameter stenosis was significantly smaller in the SAP group than others (AMI with PR 91±12% vs. AMI without PR 86±13% vs. SAP 65±9%, p<0.001). The prevalence of CCs was significantly higher in the AMI with PR group than others (AMI with PR 78% vs. AMI without PR 41% vs. SAP 39%, p<0.001). The prevalence of superficial type CCs was significantly different among the groups (AMI with PR 72% vs. AMI without PR 24% vs. SAP 7%, p<0.001). Multivariable logistic analysis demonstrated that lipid plaque (OR 84.5, 95% CI [6.30–11332.33], p<0.001) and superficial type CC (OR 9.5, 95% CI [2.61–34.89], p<0.001) were independent predictors of PR.

Conclusion

Plaque with CCs invading the fibrous cap is frequently associated with PR in patients with AMI, suggesting. In vivo CC detection is a new morphological feature for plaque rupture.

Acknowledgement/Funding

This study was supported by a grant from JSPS KAKENHI (17K09557).

P3365Relationship between early diastolic intra-ventricular pressure gradient shortly after aortic valve closure estimated by vector flow mapping and left ventricular diastolic untwisting rate in humans

Background

Early diastolic suction is an important determinant of early diastolic function. Previous studies using color Doppler M-mode and speckle-tracking echocardiography have shown left ventricular (LV) early diastolic LV untwisting rate is directly related to LV intra-ventricular pressure gradient (IVPG) between LV base and apex during early diastole. Recent introduction of vector flow mapping (VFM) using combination of color Doppler and speckle-tracking echocardiography provides noninvasive and feasible assessment of early diastolic IVPG shortly after aortic valve closure including isovolmic relaxation period (ED-IVPG) in humans. However, relationship between VFM–derived ED-IVPG and early diastolic LV untwisting rate has not been well investigated.

Purpose

The purpose of this study was to examine relationship between ED-IVPG estimated by VFM and LV untwisting rate by speckle-tracking echocardiography.

Methods

The study population consists of 66 patients without segmental wall motion abnormality, significant valvular diseases, and atrial fibrillation who underwent echocardiography for evaluation of LV function (age: 60±15 years, LVEF: 49±16%). From the apical long-axis views by color Doppler echocardiography, we analyzed peak ED-IVPG between LV base and apex just after aortic valve closure (figure) using commercially available VFM analysis software (DAS-RS1, Hitachi). We assessed peak early diastolic LV untwisting rate and LV torsion from LV basal and apical short-axis view by speckle-tracking echocardiography. We evaluated correlation between ED-IVPG and LV untwisting rate. We also evaluated correlation between ED-IVPG and peak systolic LV torsion, LV end-diastolic (EDV) and end-systolic volumes (ESV), ejection fraction (EF), early diastolic velocity (E) of LV inflow, average early diastolic velocity (e') of mitral annulus, and average E/e'.

Results

In all the study patients, ED-IVPG was successfully and quickly evaluated. 1) ED-IVPG correlated well with peak LV untwisting rate (r=0.64, p<0.0001). 2) ED-IVPG significantly correlated with LV torsion, LVEDV, LVESV, and LVEF (r=0.47, r=−0.48, r=−0.46, and r=0.48, respectively, p<0.001). 3) There were no significant correlations between ED-IVPG and other indexes including E, average e', and average E/e'. According to receiver operating characteristic analysis, the best cut-off value of ED-IVPG for determining impaired LV untwisting rate (<80 degrees/s) was found at 0.42 mmHg (sensitivity 81%, specificity 76%, and area under the curve 0.86)

ED-IVPG measurement by VFM

Conclusions

The present results showed that noninvasive VFM-derived peak ED-IVPG shortly after aortic valve closure is related to early diastolic peak LV untwisting rate. ED-IVPG easily and quickly estimated by VFM may be used as an additional index for LV diastolic function.

P2453Value of pre-operative left atrial minimum volume as a surrogate for post-operative symptoms in patients with aortic stenosis who underwent aortic valve replacement

Background

Previous reports have shown that symptoms after aortic valve replacement (AVR) are not uncommon depending on severity of myocardial fibrosis in patients with severe aortic stenosis (AS). Pre-operative minimum left atrial volume (LAVmin) at end-diastole determined by direct exposure of left ventricular end-diastolic pressure may be used as a surrogate for post-operative symptoms in patients with severe AS undergoing AVR.

Purpose

The purpose of this study was to examine the value of pre-operative echocardiographic LAVmin index (LAVImin) to predict post-operative symptomatic status after AVR in patients with severe AS.

Methods

The study population consisted of 219 patients with severe AS who underwent AVR and were followed up for 1000 days after AVR. Pre-operative maximum LAV index (LAVImax), LAVImin, LA emptying fraction (LAEF), LV volume indexes, LV ejection fraction (LVEF) by biplane Simpson's method, aortic valve area index (AVAI), mean aortic valve pressure gradient (mAV-PG), E/A, mean E/e' from LV inflow and mitral annular velocity, and pulmonary artery systolic pressure (PASP) were evaluated by Doppler echocardiography.

Results

After exclusion of 136 patients who met the exclusion criteria (atrial fibrillation, significant coronary artery disease, significant mitral valve diseases, pacemaker rhythm, and inadequate echocardiographic images), the final study population consisted of 75 patients (75±7 years old, 46 female). During a follow-up, 19 patients (25%) complained post-operative symptoms. There were no significant differences in pre-operative serum hemoglobin, creatinine, BNP, chronic obstructive pulmonary disease, hypertension, diabetes, LV volume indexes, LVEF, AVA, mAV-PG between patients with and without post-operative symptoms. There were significant differences in pre-operative LAVImax, LAVImin, and LAEF between patients with and without post-operative symptoms. (60±15 vs 47±15 ml/m2, 45±15 vs 28±1 ml/m2, and 29±12 vs 42±11 ml/m2, respectively). E/A, mean E/e', and PASP in patients with symptoms were significantly greater compared with patients without symptoms (1.0±0.3 vs 0.7±0.2, 25±3 vs 18±2, 44±17 vs 32±9 mmHg, respectively). In the multivariate analysis, pre-operative LAVImin was the independent predictor of the post-operative symptomatic status after AVR (odds ratio: 1.11, 95% confidence interval: 1.04 - 1.18). Receiver operating characteristic analysis revealed that area under the curve (AUC) of LAVImin (cutoff: 30ml/m2) for post-operative symptoms was the largest (0.84) among the other echocardiographic parameters, and significantly larger than that of mean E/e' (0.67, *p<0.01) and LVEF (0.53, **p<0.05) (figure).

Figure 1. ROC analysis

Conclusions

The present results suggest that pre-operative echocardiographic LAVImin may be used as a surrogate for post-operative symptomatic status after AVR in patients with severe AS.

102Diagnosis of coronary plaque rupture, plaque erosion, and calcified nodule by using near-infrared spectroscopy intravascular ultrasound

Objectives

This study sought to investigate the ability of near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) to differentiate among plaque rupture (PR), plaque erosion (PE), and calcified nodule (CN) in acute myocardial infarction (AMI) using an optical coherence tomography (OCT) diagnosis as a reference standard.

Background

In vivo, precise differentiation among PR, PE and CN is a major challenge for intravascular imaging.

Methods

The study enrolled 156 AMI patients who had a de novo culprit lesion in a native coronary artery. The culprit lesions were assessed by both NIRS-IVUS and OCT.

Results

OCT identified 112 PR, 29 PE, and 15 CN. IVUS-detected plaque ulceration showed a high specificity (100%) to identify OCT-PR although the sensitivity (62%) was intermediate. IVUS-detected convex calcium showed a high sensitivity (93%) and specificity (100%) to identify OCT-CN. In NIRS, the maximum lipid core burden index in 4 mm (maxLCBI4mm) was greatest in OCT-PR (values are median [interquartile range]) (671 [530 to 853]), followed by OCT-CN (355 [303 to 432]) and OCT-PE (283 [89 to 357]) (p<0.001). MaxLCBI4mm of <422 was the best cut-off to discriminate OCT-PE from OCT-PR and OCT-CN. The NIRS-IVUS classification algorithm using plaque ulceration, convex calcium, and maxLCBI4mm <422 showed a sensitivity and specificity of 96% and 95% for identifying OCT-PR, 93% and 95% for OCT-PE, and 93% and 100% for OCT-CN, respectively.

NIRS-IVUS classification algorism

Conclusion

Lipid component assessed by NIRS-IVUS was different among OCT-PR, OCT-PE and OCT-CN. The NIRS-IVUS classification algorism was highly sensitive and specific for differentiating these unstable lesion types in AMI.

Acknowledgement/Funding

None

P4349Simple and rapid estimation of left ventricular longitudinal deformation by tissue-tracking mitral annular displacement in single apical view

Background

Noninvasive assessment of left ventricular (LV) deformation using global longitudinal strain (GLS) has prognostic value in patients with and without preserved ejection fraction (EF). Application of speckle-tracking technology to the mitral annulus provides rapid and easy assessment of displacement of septal and lateral mitral annulus and mid-point of mitral annular line in single apical view (TMAD) even in poor echo-image quality. TMAD may be used as a simple index of LV longitudinal deformation in patients with and without preserved EF (Figure).

Purpose

The purpose of this study was to examine whether TMAD can be used as a simple index of LV longitudinal deformation in patients with and without preserved EF.

Methods

The study population consists of 95 patients without segmental wall motion abnormality, significant valvular diseases, and atrial fibrillation in whom both TMAD and GLS measurements were applied by QLAB software (Philips). We estimated GLS from apical 4- and 2-chamber views and apical longitudinal views, and TMAD from apical 4-chamber view. TMAD was automatically and quickly evaluated as the base-to-apex displacement of septal (TMADsep), lateral (TMADlat), and mid-point of annular line (TMADmid) (Figure). The percentage of M-TMAD to LV length from the mid-point of mitral annuls to the apex at end-diastole (%TMADmid) was also calculated. We compared each TMAD values with GLS values by linear regression analysis, and evluated TMAD values by a receiver operating characteristic (ROC) analysis to detect impaired LV longitudinal deformation (|GLS|<12.0%).

Results

TMAD was successfully assessed in 94 of 95 patients (99%) while GLS was measured in 84 of 95 patients (87%, p=0.0082 vs TMAD). There were good correlations between each TMAD index and |GLS| (TMADsep:r=0.77, TMADlat:r=0.81, TMADmid:r=0.82, %TMADmid:r=0.87). According to ROC curve, the best cut-off values for TMADsep, TMADlat, TMADmid, and %TMADmid in determining LV longitudinal deformation were 6.8mm, 8.0mm, 7.8mm, and 9.5% respectively (Table).

Conclusions

The present results suggest that rapid and easy assessment of TMAD in single apical view may be used as a simple index of LV longitudinal deformation.

Diffusion Tensor Model links to Neurite Orientation Dispersion and Density Imaging at high b-value in Cerebral Cortical Gray Matter

Diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) are widely used models to infer microstructural features in the brain from diffusion-weighted MRI. Several studies have recently applied both models to increase sensitivity to biological changes, however, it remains uncertain how these measures are associated. Here we show that cortical distributions of DTI and NODDI are associated depending on the choice of b-value, a factor reflecting strength of diffusion weighting gradient. We analyzed a combination of high, intermediate and low b-value data of multi-shell diffusion-weighted MRI (dMRI) in healthy 456 subjects of the Human Connectome Project using NODDI, DTI and a mathematical conversion from DTI to NODDI. Cortical distributions of DTI and DTI-derived NODDI metrics were remarkably associated with those in NODDI, particularly when applied highly diffusion-weighted data (b-value = 3000 sec/mm²). This was supported by simulation analysis, which revealed that DTI-derived parameters with lower b-value datasets suffered from errors due to heterogeneity of cerebrospinal fluid fraction and partial volume. These findings suggest that high b-value DTI redundantly parallels with NODDI-based cortical neurite measures, but the conventional low b-value DTI is hard to reasonably characterize cortical microarchitecture.

Temporal subtraction of computed tomography images improves detectability of bone metastases by radiology residents

OBJECTIVE

Temporal subtraction of CT (TS) images improves detection of newly developed bone metastases (BM). We sought to determine whether TS improves detection of BM by radiology residents as well.

METHODS

We performed an observer study using a previously reported dataset, consisting of 60 oncology patients, each with previous and current CT images. TS images were calculated using in-house software. Four residents independently interpreted twice the 60 sets of CT images, without and with TS. They identified BM by marking suspicious lesions likely to be BM. Lesion-based sensitivity and number of false positives per patient were calculated. Figure-of-merit (FOM) was calculated. Detectability of BM, with and without TS, was compared between radiology residents and board-certified radiologists, as published previously.

RESULTS

FOM of residents significantly improved by implementing TS (p value < 0.0001). Lesion-based sensitivity, false positives per patients, and FOM were 40.8%, 0.121, and 0.657, respectively, without TS, and 58.1%, 0.0958, and 0.796, respectively, with TS. These findings were comparable with the previously published values for board-certified radiologists without TS (58.0%, 0.19, and 0.758, respectively).

CONCLUSION

The detectability of BM by residents improved markedly by implementing TS and reached that of board-certified radiologists without TS.

KEY POINTS

• Detectability of bone metastases on CT by residents improved significantly when using temporal subtraction of CT (TS). • Detections by residents with TS and board-certified radiologists without TS were comparable. • TS is useful for residents as it is for board-certified radiologists.

CT temporal subtraction improves early detection of bone metastases compared to SPECT

OBJECTIVES

To compare observer performance of detecting bone metastases between bone scintigraphy, including planar scan and single-photon emission computed tomography, and computed tomography (CT) temporal subtraction (TS).

METHODS

Data on 60 patients with cancer who had undergone CT (previous and current) and bone scintigraphy were collected. Previous CT images were registered to the current ones by large deformation diffeomorphic metric mapping; the registered previous images were subtracted from the current ones to produce TS. Definitive diagnosis of bone metastases was determined by consensus between two radiologists. Twelve readers independently interpreted the following pairs of examinations: NM-pair, previous and current CTs and bone scintigraphy, and TS-pair, previous and current CTs and TS. The readers assigned likelihood levels to suspected bone metastases for diagnosis. Sensitivity, number of false positives per patient (FPP), and reading time for each pair of examinations were analysed for evaluating observer performance by performing the Wilcoxon signed-rank test. Figure-of-merit (FOM) was calculated using jackknife alternative free-response receiver operating characteristic analysis.

RESULTS

The sensitivity of TS was significantly higher than that of bone scintigraphy (54.3% vs. 41.3%, p = 0.006). FPP with TS was significantly higher than that with bone scintigraphy (0.189 vs. 0.0722, p = 0.003). FOM of TS tended to be better than that of bone scintigraphy (0.742 vs. 0.691, p = 0.070).

CONCLUSION

Sensitivity of TS in detecting bone metastasis was significantly higher than that of bone scintigraphy, but still limited to 54%. TS might be superior to bone scintigraphy for early detection of bone metastasis.

KEY POINTS

• Computed tomography temporal subtraction was helpful in early detection of bone metastases. • Sensitivity for bone metastasis was higher for computed tomography temporal subtraction than for bone scintigraphy. • Figure-of-merit of computed tomography temporal subtraction was better than that of bone scintigraphy.

Non-contrast-enhanced 3D MR portography within a breath-hold using compressed sensing acceleration: A prospective noninferiority study

PURPOSE

To evaluate images of non-contrast-enhanced 3D MR portography within a breath-hold (BH) using compressed sensing (CS) compared to standard respiratory-triggered (RT) sequences.

MATERIALS AND METHODS

Fifty-nine healthy volunteers underwent MR portography using two sequences of balanced steady-state free-precession (bSSFP) with time-spatial labeling inversion pulses (Time-SLIP): BH bSSFP-CS and RT bSSFP. Two radiologists independently scored the diagnostic acceptability to delineate the portal branches (MPV: main portal vein; RPV: right portal vein; LPV: left portal vein; RPPV: right posterior portal vein; and P4 and P8: portal branch of segment 4 and segment 8, respectively) and the overall image quality on a four-point scale. We assessed noninferiority of BH bSSFP-CS to RT bSSFP. For quantitative analysis, vessel-to-liver contrast (C_v-l) was calculated in MPV, RPV and LPV.

RESULTS

BH bSSFP sequence was successfully performed with a 30-second acquisition time. The diagnostic acceptability scores of BH bSSFP-CS compared with RT bSSFP were statistically noninferior: MPV (95% CI for score difference of Reader 1 and Reader 2, respectively: [-0.16, 0.06], [-0.05, 0.02]), RPV ([-0.00, 0.11], [-0.01, 0.08]), LPV ([-0.03, 0.10], [-0.10, 0.03]), RPPV ([-0.03, 0.10], [-0.05, 0.05]), P4 ([-0.13, 0.34], [-0.28, 0.21]) and P8 ([-0.21, 0.11], [-0.25, -0.02]). However, the overall image quality of BH bSSFP-CS did not show noninferiority ([-0.61, -0.24], [-0.54, -0.17]). C_v-l values were significantly lower in BH bSSFP-CS (P<0.001).

CONCLUSION

CS enabled non-contrast-enhanced 3D bSSFP MR portography to be performed within a BH while maintaining noninferior diagnostic acceptability compared to standard RT bSSFP MR portography.

Temporal Subtraction of Serial CT Images with Large Deformation Diffeomorphic Metric Mapping in the Identification of Bone Metastases

Purpose To determine the improvement of radiologist efficiency and performance in the detection of bone metastases at serial follow-up computed tomography (CT) by using a temporal subtraction (TS) technique based on an advanced nonrigid image registration algorithm. Materials and Methods This retrospective study was approved by the institutional review board, and informed consent was waived. CT image pairs (previous and current scans of the torso) in 60 patients with cancer (primary lesion location: prostate, n = 14; breast, n = 16; lung, n = 20; liver, n = 10) were included. These consisted of 30 positive cases with a total of 65 bone metastases depicted only on current images and confirmed by two radiologists who had access to additional imaging examinations and clinical courses and 30 matched negative control cases (no bone metastases). Previous CT images were semiautomatically registered to current CT images by the algorithm, and TS images were created. Seven radiologists independently interpreted CT image pairs to identify newly developed bone metastases without and with TS images with an interval of at least 30 days. Jackknife free-response receiver operating characteristics (JAFROC) analysis was conducted to assess observer performance. Reading time was recorded, and usefulness was evaluated with subjective scores of 1-5, with 5 being extremely useful and 1 being useless. Significance of these values was tested with the Wilcoxon signed-rank test. Results The subtraction images depicted various types of bone metastases (osteolytic, n = 28; osteoblastic, n = 26; mixed osteolytic and blastic, n = 11) as temporal changes. The average reading time was significantly reduced (384.3 vs 286.8 seconds; Wilcoxon signed rank test, P = .028). The average figure-of-merit value increased from 0.758 to 0.835; however, this difference was not significant (JAFROC analysis, P = .092). The subjective usefulness survey response showed a median score of 5 for use of the technique (range, 3-5). Conclusion TS images obtained from serial CT scans using nonrigid registration successfully depicted newly developed bone metastases and showed promise for their efficient detection. ^© RSNA, 2017 Online supplemental material is available for this article.

Juxtacortical Chondroma of the Hand: Treatment by Resection of the Tumour and the Adjacent Bone Cortex

A recurrence of a juxtacortical chondroma of the finger after marginal excision prompted us to review the treatment of this condition. Although the recommended treatment is simple curettage or marginal excision, the reported recurrence rate is significantly higher for lesions in the hand than those in other locations and recurrences only occurred in patients who had local treatments which did not include excision of the adjacent bone cortex.

We report five patients with juxtacortical chondroma of the fingers. The first patient underwent marginal excision without resection of the underlying bone cortex. The other four patients underwent intralesional, marginal or wide excisions of tumour with resection of the bone cortex underlying the lesion. Recurrence was only seen in the patient who did not undergo resection of the bone cortex. Resection of the underlying bone cortex after excision of this tumour may be advisable for the treatment of this tumour in the hand to reduce the rate of recurrence.

Optimization of Regularization Parameters in Compressed Sensing of Magnetic Resonance Angiography: Can Statistical Image Metrics Mimic Radiologists' Perception?

In Compressed Sensing (CS) of MRI, optimization of the regularization parameters is not a trivial task. We aimed to establish a method that could determine the optimal weights for regularization parameters in CS of time-of-flight MR angiography (TOF-MRA) by comparing various image metrics with radiologists' visual evaluation. TOF-MRA of a healthy volunteer was scanned using a 3T-MR system. Images were reconstructed by CS from retrospectively under-sampled data by varying the weights for the L1 norm of wavelet coefficients and that of total variation. The reconstructed images were evaluated both quantitatively by statistical image metrics including structural similarity (SSIM), scale invariant feature transform (SIFT) and contrast-to-noise ratio (CNR), and qualitatively by radiologists' scoring. The results of quantitative metrics and qualitative scorings were compared. SSIM and SIFT in conjunction with brain masks and CNR of artery-to-parenchyma correlated very well with radiologists' visual evaluation. By carefully selecting a region to measure, we have shown that statistical image metrics can reflect radiologists' visual evaluation, thus enabling an appropriate optimization of regularization parameters for CS.

The Dixon technique and the frequency-selective fat suppression technique in three-dimensional T1 weighted MRI of the liver: a comparison of contrast-to-noise ratios of hepatocellular carcinomas-to-liver

OBJECTIVE

The use of three-dimensional T1 weighted gradient echo sequences such as the Dixon technique and the frequency-selective fat suppression (FS) technique is currently widely accepted method in MRI examinations of the liver. To assess the image qualities of the Dixon technique and the frequency-selective FS technique, the contrast-to-noise ratios (CNRs) of hepatocellular carcinoma (HCC)-to-liver and fat-to-liver were compared between the two techniques in the hepatobiliary phase (HBP) following administration of gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid.

METHODS

MR images of 59 patients with a total of 86 HCCs were retrospectively evaluated. Images were consecutively obtained with the Dixon and frequency-selective FS methods in the HBP and their CNRs of HCC-to-liver and fat-to-liver were compared. CNRs and contrast ratios were calculated by the mean value of the liver parenchyma, HCC, fat and standard deviation of the liver parenchyma. The Wilcoxon signed-ranks test was used for statistical analysis.

RESULTS

The median CNRs for the frequency-selective FS and Dixon techniques of HCC-to-liver were 4.3 and 5.4 (p < 0.01), mesenteric fat-to-liver were 9.9 and 12.8 (p < 0.01) and subcutaneous fat-to-liver were 9.9 and 13.2 (p < 0.01), respectively.

CONCLUSION

The Dixon technique yielded higher CNRs of HCC-to-liver than that of the frequency-selective FS technique.

ADVANCES IN KNOWLEDGE

There are a limited number of reports on quantitative analysis of the image qualities of the Dixon technique and the frequency-selective FS technique, particularly within the same patient and examination.