Adenosine triphosphate stress myocardial perfusion imaging for risk stratification of patients aged 70 years and older with suspected coronary artery disease

Objective

We investigated the cardiac risk stratification value of adenosine triphosphate stress myocardial perfusion imaging (ATP-MPI) in patients aged 70 years and older with suspected coronary artery disease (CAD).

Methods

We identified a series of 415 consecutive patients aged 70 years and older with suspected CAD, who had undergone ATP-MPI with ^99mTc-MIBI. The presence of a fixed and/or reversible perfusion defect was considered as an abnormal MPI. Follow-up was available in 399 patients (96.1%) over 3.45 ± 1.71 years after excluding 16 patients who underwent early coronary revascularization <60 days after MPI. The major adverse cardiac events (MACE), including cardiac death, nonfatal infarction, and late coronary revascularization, were recorded.

Results

One hundred twenty-five (31.3%) patients had abnormal MPI and the remaining had normal MPI. A multivariable analysis using Cox regression demonstrated that abnormal MPI was independently associated with MACE (hazard ratio 19.50 and 95% confidence interval 5.91-64.31, P value .000). The patients with SSS > 8 had significantly higher cumulative MACE rate than patients with SSS ≤ 8 had (37.8% vs 5.2%, respectively, P < .001). The Kaplan-Meier cumulative MACE-free survival in patients with abnormal MPI (57.0%) was significantly lower than that in patients with normal MPI (89.6%), P < .0001. Among patients with SSS > 8, the Kaplan-Meier cumulative MACE-free survival were 36.9% in patients ≥80 years old and 49.5% in patients 70-79 years old, respectively, P < .05. However, among patients with SSS ≤ 8, there was no difference between the Kaplan-Meier cumulative MACE-free survivals of these two age groups.

Conclusions

ATP-MPI data are useful for the prediction of major adverse cardiac events in patients aged 70 years and older with suspected CAD.

     

Determinants of left ventricular mechanical dyssynchrony in patients submitted to myocardial perfusion imaging: A cardiac CZT study

Background

An interaction between coronary anatomy, myocardial perfusion, and left ventricular (LV) functional parameters in the development of mechanical LV dyssynchrony (LVD) has been suggested. This study examined the correlates of LVD in a large sample size of patients with known or suspected coronary artery disease (CAD) using cadmium-zinc-telluride camera.

Methods

Six-hundred and fifty-seven consecutive patients who underwent myocardial perfusion imaging (MPI) and coronary angiography were included. Coronary stenosis >70% was considered significant. LV perfusion and functional parameters were computed from MPI images. The presence of significant LVD was evaluated by phase standard deviation and histogram bandwidth.

Results

415/657 (63%) patients had significant CAD. LVD was present in 247 (38%) patients and was associated with the presence of a higher CAD burden (P < .001), more impaired measures of LV perfusion (P < .001), contractile function (P < .001), and larger LV volumes (P < .001). By multivariate analysis, the LV end-systolic volume index (P < .001) and ischemic burden (P < .001) were the strongest predictors of LVD independent of CAD extent and LV systolic dysfunction.

Conclusions

LVD is frequent in patients undergoing MPI for suspected or known CAD. Its presence is independent of CAD burden and LV systolic dysfunction, but is dependent on the presence of myocardial perfusion abnormalities and LV end-systolic volume.

     

Impact of initial myocardial perfusion imaging versus invasive coronary angiography on outcomes in coronary artery disease: a nationwide cohort study

Purpose

In patients with stable coronary artery disease (CAD), two main options exist to guide management: initial invasive coronary angiography (CAG), or selective CAG after risk stratification using myocardial perfusion imaging (MPI). This study compared clinical outcomes between these two strategies in a large, real-world population.

Methods

The initial cohort comprised 1,000,000 randomly selected patients who had been entered in the National Health Insurance Research Database of Taiwan between 2000 and 2011. Patients with acute coronary syndromes, prior myocardial infarction (MI) or coronary revascularization, and prior treadmill testing or stress echocardiography were excluded. The remaining patients with suspected or known CAD were divided into those in whom initial CAG had been performed and those in whom initial MPI had been performed, and were followed until the end of 2011 for all-cause mortality, MI, and revascularization. A Cox proportional hazards model was used to estimate the risk of events after adjusting for covariates.

Results

The MPI and CAG groups each comprised 4,495 patients after frequency matching, with a similar Charlson comorbidity index (CCI). The MPI group had a significantly and dramatically lower incidence of revascularization (729 vs. 2,380, p < 0.001), MI (268 vs. 1,044, p < 0.001), and all-cause mortality (522 vs. 784, p < 0.001) than the CAG group. Multivariable analysis adjusting for age, gender, CCI, and comorbidities showed that in the MPI group fewer patients had revascularization (HR 0.24, 95% CI 0.22–0.26) and MI (HR 0.23, 95% CI 0.20–0.26), and the rate of all-cause mortality was lower (HR 0.58, 95% CI 0.52–0.64).

Conclusions

In patients with suspected stable CAD, compared with initial invasive CAG, a selective strategy guided by MPI was associated with lower rates of revascularization and MI and improved survival.

     

Differential risk reclassification improvement by exercise testing and myocardial perfusion imaging in patients with suspected and known coronary artery disease

Objective

The objective of this study is to compare the incremental prognostic and net risk reclassification value of exercise testing alone vs exercise myocardial perfusion imaging (MPI) for estimating the risk of death in patients with suspected and known coronary artery disease (CAD).

Methods

6702 patients with suspected CAD and 2008 with known CAD had treadmill exercise MPI and were followed for 2.5 ± 0.9 years for the occurrence of all-cause death. The estimation of risk of death and net reclassification improvement (NRI) were examined in three models. Model 1: clinical variables; Model 2: model 1+Duke Treadmill Score; and Model 3: model 2+ MPI variables. Risk estimates were categorized as <1%, 1-3%, and >3% risk of death per year.

Results

In patients with suspected CAD, the global Chi-square for predicting risk of death increased significantly for Model 2 compared to Model 1 (74.78 vs 63.86 to (P = .001). However, adding MPI variables in Model 3 did not further improve predictive value (Chi-square 79.38, P = .10). In patients with suspected CAD risk, reclassification improved significantly in Model 2 over Model 1 (NRI = 0.12, 95% CI 0.02 to 0.22, P = .019), but not in Model 3 (NRI = 0.0009, 95% CI ?0.072 to 0.070; P = .98). In contrast, in patients with known CAD Model 2 did not yield significant improvements for predicting risk and risk reclassification compared to Model 1. However, global Chi-square of Model 3 was significantly higher than that of Model 2 (30.03 vs 6.56, P < .0001) with associated significant reclassification improvement (NRI = 0.26 95% CI 0.067 to 0.46. P = .0084).

Conclusion

Risk reclassification by diagnostic testing is importantly influenced by baseline characteristics of patient cohorts. In patients with suspected CAD, NRI is predominately achieved by exercise variables, whereas in patients with known CAD, greatest NRI is obtained by MPI variables.

     

Prognosis of stress-only SPECT myocardial perfusion imaging with prone imaging

Background

Stress-only single-photon emission computed tomography myocardial perfusion imaging (SO SPECT MPI) is associated with similarly benign prognosis as stress-rest SPECT MPI. However, previous studies have used attenuation correction rather than prone imaging to increase the rate of SO studies.

Objectives

To assess the prognosis of SO SPECT MPI performed with prone imaging.

Methods

We performed a retrospective cohort analysis of all patients who underwent a Tc-99m gated SPECT MPI over a 58-month period.

Results

Two thousand four hundred and sixty five patients were followed up. Of them, 1114 (45.2%) patients had a SO supine test, 388 (15.7%) underwent a SO supine and prone test, and the remaining 963 (39.1%) patients underwent a full stress-rest SPECT MPI. There was a similar annual mortality rate between the SO supine/prone group (1.3%), the SO supine (1.5%), and the stress-rest (1.5%) group (P = 0.47). Patients in the stress-rest group were significantly more likely to suffer from myocardial infarction (MI) as compared to the other two groups with an annual rate of 0.7% as compared to 0.4% (P = 0.049).

Conclusions

Normal supine-prone SO SPECT MPI is associated with a similarly benign prognosis as stress-rest SPECT MPI. The adjunction of prone imaging to the stress supine significantly increases the rate of SO SPECT MPI

     

Computed tomography of the chest with model-based iterative reconstruction using a radiation exposure similar to chest X-ray examination: preliminary observations

Objectives

The purpose of this study was to assess the diagnostic image quality of ultra-low-dose chest computed tomography (ULD-CT) obtained with a radiation dose comparable to chest radiography and reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) in comparison with standard dose diagnostic CT (SDD-CT) or low-dose diagnostic CT (LDD-CT) reconstructed with FBP alone.

Methods

Unenhanced chest CT images of 42 patients acquired with ULD-CT were compared with images obtained with SDD-CT or LDD-CT in the same examination. Noise measurements and image quality, based on conspicuity of chest lesions on all CT data sets were assessed on a five-point scale.

Results

The radiation dose of ULD-CT was 0.16?±?0.006 mSv compared with 11.2?±?2.7 mSv for SDD-CT (P?<?0.0001) and 2.7?±?0.9 mSv for LDD-CT. Image quality of ULD-CT increased significantly when using MBIR compared with FBP or ASIR (P?<?0.001). ULD-CT reconstructed with MBIR enabled to detect as many non-calcified pulmonary nodules as seen on SDD-CT or LDD-CT. However, image quality of ULD-CT was clearly inferior for characterisation of ground glass opacities or emphysema.

Conclusion

Model-based iterative reconstruction allows detection of pulmonary nodules with ULD-CT with radiation exposure in the range of a posterior to anterior (PA) and lateral chest X-ray.

Key Points

? Radiation dose is a key concern with the increased use of thoracic CT ? Ultra-low-dose chest CT approximates the radiation dose of conventional chest radiography ? Ultra-low-dose chest CT can be of diagnostic quality ? Solid pulmonary nodules are clearly depicted on ultra-low-dose chest CT

     

Reduction of metal artifacts due to dental hardware in computed tomography angiography: assessment of the utility of model-based iterative reconstruction

Purpose

The aim of this study is to assess the value of adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) for reduction of metal artifacts due to dental hardware in carotid CT angiography (CTA).

Methods

Thirty-seven patients with dental hardware who underwent carotid CTA were included. CTA was performed with a GE Discovery CT750 HD scanner and reconstructed with filtered back projection (FBP), ASIR, and MBIR. We measured the standard deviation at the cervical segment of the internal carotid artery that was affected most by dental metal artifacts (SD₁) and the standard deviation at the common carotid artery that was not affected by the artifact (SD₂). We calculated the artifact index (AI) as follows: AI = [(SD₁)2 ? (SD₂)2]1/2 and compared each AI for FBP, ASIR, and MBIR. Visual assessment of the internal carotid artery was also performed by two neuroradiologists using a five-point scale for each axial and reconstructed sagittal image. The inter-observer agreement was analyzed using weighted kappa analysis.

Results

MBIR significantly improved AI compared with FBP and ASIR (p < 0.001, each). We found no significant difference in AI between FBP and ASIR (p = 0.502). The visual score of MBIR was significantly better than those of FBP and ASIR (p < 0.001, each), whereas the scores of ASIR were the same as those of FBP. Kappa values indicated good inter-observer agreements in all reconstructed images (0.747–0.778).

Conclusions

MBIR resulted in a significant reduction in artifact from dental hardware in carotid CTA.

     

Iterative image reconstruction algorithms in coronary CT angiography improve the detection of lipid-core plaque – a comparison with histology

Objectives

To evaluate whether iterative reconstruction algorithms improve the diagnostic accuracy of coronary CT angiography (CCTA) for detection of lipid-core plaque (LCP) compared to histology.

Methods and materials

CCTA and histological data were acquired from three ex vivo hearts. CCTA images were reconstructed using filtered back projection (FBP), adaptive-statistical (ASIR) and model-based (MBIR) iterative algorithms. Vessel cross-sections were co-registered between FBP/ASIR/MBIR and histology. Plaque area <60 HU was semiautomatically quantified in CCTA. LCP was defined by histology as fibroatheroma with a large lipid/necrotic core. Area under the curve (AUC) was derived from logistic regression analysis as a measure of diagnostic accuracy.

Results

Overall, 173 CCTA triplets (FBP/ASIR/MBIR) were co-registered with histology. LCP was present in 26 cross-sections. Average measured plaque area <60 HU was significantly larger in LCP compared to non-LCP cross-sections (mm²: 5.78?±?2.29 vs. 3.39?±?1.68 FBP; 5.92?±?1.87 vs. 3.43?±?1.62 ASIR; 6.40?±?1.55 vs. 3.49?±?1.50 MBIR; all p?<?0.0001). AUC for detecting LCP was 0.803/0.850/0.903 for FBP/ASIR/MBIR and was significantly higher for MBIR compared to FBP (p?=?0.01). MBIR increased sensitivity for detection of LCP by CCTA.

Conclusion

Plaque area <60 HU in CCTA was associated with LCP in histology regardless of the reconstruction algorithm. However, MBIR demonstrated higher accuracy for detecting LCP, which may improve vulnerable plaque detection by CCTA.

Key Points

? A low attenuation plaque area is associated with the presence of lipid-core plaque ? MBIR leads to higher diagnostic accuracy for detecting lipid-core plaque ? The benefit of MBIR is mainly due to increased sensitivity at high specificities ? Semiautomated CCTA assessment can detect vulnerable plaques non-invasively

     

Prognostic significance of impaired chronotropic response to pharmacologic stress Rb-82 PET

Background

An impaired chronotropic response to exercise is an accepted risk marker but the relationship between heart rate reserve (HRR) with pharmacologic stress is less well-established. The primary aim of this analysis was to evaluate the prognostic significance of HRR in patients undergoing rest/stress myocardial perfusion positron emission tomography (PET) in estimating coronary artery disease (CAD) mortality.

Methods

This subset analysis from the PET Prognosis Multicenter Registry includes a total of 2,398 patients undergoing rest/stress Rb-PET from three participating sites. The HRR from rest to peak stress was categorized into tertiles of ≤4, 5-14, and ≥15 beats per minute (bpm). At stress, the % abnormal myocardium was categorized as <5 %, 5-9.9 %, and ≥10 %. We estimated CAD mortality using univariable and multivariable Cox proportional hazard models.

Results

CAD mortality was 12.8 %, 3.4 %, and 0.8 %, respectively, for HRR measurements of ≤4, 5-14, and ≥15 bpm (P < 0.0001). In a multivariable model, the HRR was independently predictive of CAD mortality (P < 0.0001) with adjusted hazard ratios elevated 3.5- and 8.4-fold for HRR of 5-14 and ≤4 versus ≥15 bpm. In a multivariable model, both the HRR and stress MPI % abnormal myocardium were independently and highly predictive of CAD mortality. Moreover, the net reclassification improvement was 0.18 for the HRR when compared to a model including risk factors, symptoms, rest HR, and PET variables (P = 0.0008). For those with ≥10 % abnormal myocardium on stress PET, there was a graded relationship between HRR and CAD mortality with adjusted hazards exceeding 50-fold for measurements of 5-14 and ≤4 bpm (P < 0.0001) compared to stress MPI with <5 % abnormal myocardium and a HRR ≥15 bpm.

Conclusion

A diminished HRR to vasodilator stress is a novel but increasingly important predictor of CAD mortality. HRR measurements of ≤4, 5-14, and ≥15 bpm were independently predictive of CAD mortality and underscore the importance of optimizing readily available novel markers of risk as highly relevant to identifying high and low risk patient subsets.

     

No difference in prevalence of spine and hip pain in young Elite skiers

Purpose

To investigate the prevalence between back and hip pain in young Elite skiers.

Methods

Sample group (n = 102), consisted of young Elite skiers (n = 75) and age-matched non-athletes (n = 27), all completed a three-part back and hip pain questionnaire, Oswestry Disability Index and EuroQoL to evaluate general health, activity level, back and hip pain prevalence.

Results

No significant differences were shown for lifetime prevalence of back pain in the skiers (50%) compared with controls (44%) (n.s.). Duration of back pain for the skiers showed (30%) > 1 year, whilst (46%) > 5 years. A significant difference was shown with increased Visual Analogue Scale back pain levels for skiers 5.3 (SD 3.1) compared with controls 2.4 (SD 1.9, p = 0.025). No significant differences were shown for lifetime prevalence of hip pain in skiers (21%) compared with controls (8%) (n.s.).

Conclusion

Young Elite skiers are shown not to have increased lifetime prevalence for back and hip pain compared with a non-athletic control group.

Level of evidence

II.

     

Postprandial changes in secretory flow of pancreatic juice in the main pancreatic duct: evaluation with cine-dynamic MRCP with a spatially selective inversion-recovery (IR) pulse

Purpose

To evaluate the influence of oral ingestion on the secretory flow dynamics of physiological pancreatic juice within the main pancreatic duct in healthy subjects by using cine-dynamic MRCP with spatially-selective inversion-recovery (IR) pulse non-invasively.

Materials and methods

Thirty-eight healthy subjects were investigated. MRCP with spatially-selective IR pulse was repeated every 15 s for 5 min to acquire a total of 20 images (cine-dynamic MRCP). A set of 20 MRCP images was repeatedly obtained before and after liquid oral ingestion every 7 min (including 2-min interval) for 40 min (a total of seven sets). Secretion grade of pancreatic juice on cine-dynamic MRCP was compared before and after oral ingestion using the nonparametric Wilcoxon signed-rank test.

Results

Median secretion grades of pancreatic juice at 5 min (score?=?2.15), 12 min (score?=?1.95) and 19 min (score?=?2.05) after ingestion were significantly higher than that before ingestion (score?=?1.40) (P?=?0.004, P?=?0.032, P?=?0.045, respectively). Secretion grade of pancreatic juice showed a maximum peak of 2.15 at 5 min after ingestion. Thereafter, the secretion grade of pancreatic juice tended to gradually decline.

Conclusion

Non-invasive cine-dynamic MRCP using spatially-selective IR pulse showed potential for evaluating postprandial changes in the secretory flow dynamics of pancreatic juice as a physiological reaction.

Key Points

? Secretion grade of pancreatic juice at cine-dynamic MRCP after ingestion was evaluated. ? Secretion grade was significantly increased within 19 min after liquid meal ingestion. ? Secretion grade showed maximum peak of 2.15 at 5 min after ingestion. ? Postprandial changes in pancreatic juice flow can be assessed by cine-dynamic MRCP.

     

Image quality and dose optimisation for infant CT using a paediatric phantom

Objective

To optimise image quality and reduce radiation exposure for infant body CT imaging.

Methods

An image quality CT phantom was created to model the infant body habitus. Image noise, spatial resolution, low contrast detectability and tube current modulation (TCM) were measured after adjusting CT protocol parameters. Reconstruction method (FBP, hybrid iterative and model-based iterative), image quality reference parameter, helical pitch and beam collimation were systematically investigated for their influence on image quality and radiation output.

Results

Both spatial and low contrast resolution were significantly improved with model-based iterative reconstruction (p?<?0.05). A change in the helical pitch from 0.969 to 1.375 resulted in a 23 % reduction in total TCM, while a change in collimation from 20 to 40 mm resulted in a 46 % TCM reduction. Image noise and radiation output were both unaffected by changes in collimation, while an increase in pitch enabled a dose length product reduction of ~6 % at equivalent noise. An optimised protocol with ~30 % dose reduction was identified using model-based iterative reconstruction.

Conclusions

CT technology continues to evolve and require protocol redesign. This work provides an example of how an infant-specific phantom is essential for leveraging this technology to maintain image quality while reducing radiation exposure.

Key Points

? A size-specific phantom is critical in protocol development for infant CT.? New reconstruction technology enables ~30 % dose reduction at equivalent image quality.? A consistent performance is observed for this scanner system across protocol changes.? A tradeoff exists between reducing exposure time and enabling tube current modulation.

     

Comparison of the diagnostic accuracies of very low stress-dose with standard-dose myocardial perfusion imaging: Automated quantification of one-day,stress-first SPECT using a CZT camera

Background

Previous studies have demonstrated accurate diagnosis of reduced dose myocardial perfusion imaging (MPI) using Cadmium-Zinc-Telluride (CZT) technology. We compared the diagnostic performances of very low stress-dose (<2 mSv) with standard-dose stress-first, quantitative MPI using a CZT camera.

Methods

Patients without known coronary artery– disease who underwent a stress-first Tc-99 m sestamibi CZT-MPI and invasive coronary angiography (ICA), and low-risk patients without ICA were included. A stress-rest standard-dose (10/30 mCi) MPI and a low-dose (5/15 mCi) MPI were compared. Normal limits for quantification were developed from 40 (20 males) low-risk patients, and total perfusion deficit (TPD) was derived.

Results

208 patients who underwent MPI and ICA, and 76 low-risk patients were included. Of these, 128 had a standard-dose MPI and 156 had a low-dose MPI. Stress-doses in low-dose and standard-dose groups were 5.9 ± 1.2 vs 10.2 ± 0.5 mCi (1.7 ± 0.3 vs 3.0 ± 0.1 mSv), respectively, P < 0.001, and stress-rest effective radiation was 6.9 ± 1.1 vs 11.7 ± 0.4 mSv, respectively, P < 0.001. Sensitivity, specificity, and accuracy values in the low-dose and standard-dose groups were 86.1%, 76.6%, and 81.4%; and 90.6%, 78.1%, and 84.4%, respectively, P = ns. Using TPD prone, specificity values were 84.9% and 80.3%, respectively, P = ns.

Conclusion

One-day stress-first MPI with 50% radiation reduction and a very low stress-dose (<2 mSv) using CZT technology and quantitative supine and prone analysis provided a high diagnostic value, similar to standard-dose MPI.

     

Optimal load for the muscle power profile of prone bench pull in Brazilian Jiu-Jitsu athletes

Background

No studies were observed optimal intensity loads for the muscle power performance during prone bench pull exercise in Brazilian Jiu-Jitsu athletes (BJJ) and this exercise is more similar with grip technics.

Purpose

To identify the optimal intensity for the muscle power performance variables during PBP exercise in BJJ athletes.

Methods

Fifteen athletes (25.5 ± 4.9 years; 65.6 ± 12.2 kg; 177.5 ± 4.7 cm) performed PBP at 30, 40, 50 and 60% of one repetition maximum (1RM) in a random order. The mean power (MP), mean velocity (MV), mean propulsive power (MPP) and mean propulsive velocity (MPV) were determined by measuring the barbell displacement by a linear encoder.

Results

In all power performance variables, higher power output was observed at 40 and 50% 1RM when compared to 30 and 60% 1RM (MP: F = 29.07; p < 0.001; MV: F = 40.80; p < 0.001; MPP: F = 53.69; p = 0.003; MPV: F = 166.2; p > 0.001). Additionally, it was observed higher MPP at 50% 1RM when compared to 40% 1RM (F = 55.23; p < 0.001). The polynomial adjustment indicated that the optimal intensity load for producing highest power performance ranged from 45 to 50% 1RM (R ² = 0.938–0.989) across all variables.

Conclusion

The loads between 45 and 50% 1RM produced the optimal muscle power performance during PBP exercise in BJJ athletes.

     

Outcomes after inappropriate nuclear myocardial perfusion imaging: A meta-analysis

Background

The relationship between inappropriate MPI and cardiovascular outcomes is poorly understood. We sought to systematically review the literature on appropriate use criteria (AUC) for MPI, including temporal trend of inappropriate testing and resulting cardiovascular outcomes.

Methods

We searched the MEDLINE database for studies related to AUC and MPI. The co-primary outcomes were abnormal test results and the presence of cardiac ischemia. Random effects odds ratios (OR) were constructed using DerSimonian-Laird method.

Results

A total of 22 studies with 23,443 patients were included. The prevalence of inappropriate testing was 14.8% [95% confidence interval (CI) 11.6%-18.7%]. Inappropriate MPI studies were less likely to be abnormal (OR 0.41 95% CI 0.35-0.49, P < .0001) and to demonstrate ischemia (OR 0.40, 95% CI 0.24-0.67, P < .0001) compared to appropriate testing. No difference in the rate of inappropriate tests was detected based on the midpoint of the enrollment year (P = .54). The pattern of ordering inappropriate studies was not different between cardiology and non-cardiology providers (OR 0.74, 95% CI 0.51-1.06, P = .10).

Conclusion

Inappropriate MPI studies are less likely to yield abnormal results or demonstrate myocardial ischemia. The rate of inappropriate MPI has not decreased over time.

     

Using intravoxel incoherent motion MR imaging to study the renal pathophysiological process of contrast-induced acute kidney injury in rats: Comparison with conventional DWI and arterial spin labelling

Objectives

To investigate the potential of intravoxel incoherent motion (IVIM) to assess the renal pathophysiological process in contrast-induced acute kidney injury (CIAKI).

Methods

Twenty-seven rats were induced with CIAKI model, six rats were imaged longitudinally at 24 h prior to and 30 min, 12, 24, 48, 72 and 96 h after administration; three rats were randomly chosen from the rest for serum creatinine and histological studies. D, f, D* and ADC were calculated from IVIM, and renal blood flow (RBF) was obtained from arterial spin labelling (ASL).

Results

A progressive reduction in D and ADC was observed in cortex (CO) by 3.07 and 8.62 % at 30 min, and by 25.77 and 28.16 % at 48 h, respectively. A similar change in outer medulla (OM) and inner medulla (IM) was observed at a later time point (12–72 h). D values were strongly correlated with ADC (r?=?0.885). As perfusion measurement, a significant decrease was shown for f in 12–48 h and an increase in 72–96 h. A slightly different trend was found for D*, which was decreased by 26.02, 21.78 and 10.19 % in CO, OM and IM, respectively, at 30 min. f and D* were strongly correlated with RBF in the cortex (r?=?0.768, r?=?0.67), but not in the medulla.

Conclusions

IVIM is an effective imaging tool for monitoring progress in renal pathophysiology undergoing CIAKI.

Key Points

? IVIM analysis permits separate quantification of diffusion and perfusion. ? IVIM can provide useful biomarkers ifor changes in renal pathophysiology. ? IVIM can be useful for monitoring progress in renal pathophysiology undergoing CIAKI.

     

Transcatheter Arterial Embolization for Primary Postpartum Hemorrhage: Predictive Factors of Need for Embolic Material Conversion of Gelatin Sponge Particles to <Emphasis Type="Italic">N</Emphasis>-Butyl Cyanoacrylate

Purpose

To identify predictive factors for embolic material conversion to N-butyl cyanoacrylate (NBCA) for the treatment of primary postpartum hemorrhage (PPH) after failed transcatheter arterial embolization (TAE) using gelatin sponge (GS).

Materials and Methods

Institutional review board approval was obtained. We retrospectively studied 62 consecutive women with primary PPH who underwent TAE between January 2006 and March 2015. Five of them were excluded for the following: cardiopulmonary arrest at arrival (n = 1), uterine inversion (n = 1), and hysterectomy after TAE (n = 3). Remaining 57 women (age range, 21–43 years; mean, 32.6 years) comprised study population. TAE was initially performed using GS in all cases and then converted to NBCA after two embolizations using GS with persistent hemodynamic instability or vaginal bleeding. The patients’ background, uterine height, vital signs, laboratory tests, disseminated intravascular coagulation score, and details of procedure were reviewed. Univariate and multivariate analyses were performed to determine factors related to embolic material conversion.

Results

Technical success rate was 100%. Fourteen patients (25%) needed embolic material conversion to NBCA. Univariate analysis showed that uterine height, systolic blood pressure (sBP), and hemoglobin level were significantly related to embolic material conversion to NBCA (P = 0.029, 0.030, and 0.042). Logistic regression analysis showed that uterine height (odds ratio, 1.37; P = 0.025) and sBP (odds ratio, 0.96; P = 0.003) were associated with embolic material conversion to NBCA.

Conclusion

Uterine height and sBP can be predictive factors for embolic material conversion to NBCA for the treatment of PPH.

Level of Evidence

Level 4, Case Control Study

     

Femur bowing could be a risk factor for implant flexion in conventional total knee arthroplasty and notching in navigated total knee arthroplasty

Purpose

This study aimed to investigate the relationship between preoperative femoral axes and femoral implant position and to determine how femoral sagittal axes, including femoral anterior bowing, influence the femoral component position in total knee arthroplasty (TKA).

Methods

The relationship between femoral axes (femoral anterior bowing, mechanical axis and the anterior cortical line, intramedullary axis) and implant position was compared in 50 conventional and 50 navigated TKAs. Outliers with more than a 3° margin of error in placement of the femoral component compared with the mechanical axis in the sagittal plane were calculated.

Results

The femoral component flexion angle was 3.1° in the conventional group and 1.6° in the navigation group (p < 0.001). Anterior femoral bowing correlated positively with the angle between the mechanical axis and implant (r = 0.360, p = 0.010) in the conventional group and negatively with the angle between the anterior cortical line and flange of the femoral component (r = ?0.355, p = 0.010) in navigated TKAs. Incidence of outliers was 48 % (24 patients) in the conventional group compared with 10 % (five patients) in the navigated group (p = 0.008).

Conclusions

Femoral anterior bowing was an influential factor for implant position and could be a risk factor for both femoral implant flexion in conventional TKAs and notching in navigated TKAs. The results of this study should be considered by surgeons when assessing the risk factors for femoral geometry before performing TKAs, as these results may help them to avoid an overly flexed or extended position of the femoral component, which would affect clinical long-term survival.

Level of evidence

Retrospective comparative study, Level III.

     

Prospective 1-year follow-up pilot study of CT-guided microwave ablation in the treatment of bone and soft-tissue malignant tumours

Purpose

The aims of this work were to assess the feasibility, efficacy, short-term outcome and safety of microwave ablation (MWA) in the treatment of malignant musculoskeletal tumours.

Materials and methods

Sixteen bone and soft-tissue malignant tumours were prospectively included and were treated by CT-guided MWA. The percentage and size of necrosis of the lesions were measured by contrast-enhanced MRI before the procedure and after 1, 3, 6 and 12 months. mRECIST criteria were used to assess tumour response. Procedural success was defined as ≥80 % necrosis. Patient pain (as assessed using a numeric visual scale (NVS)) and side effects were noted.

Results

Six osteolytic metastases, five osteoblastic metastases and five soft tissue sarcomas were treated. At 1 month, 40 % were treated completely, the percentage of necrosis was 85?±?30.4 %, and the success rate was 80 %. At 3, 6 and 12 months the success rate was 80 %, 76.9 % and 63.6 %, respectively. At 12 months, four lesions (36.3 %) still had no recurrence. Mean NVS during the procedure was 3.5?±?2.8. One patient had transitory sciatica without neurological deficit that was treated medically.

Conclusion

CT-guided MWA of bone and soft-tissue malignant tumours is efficient, well tolerated and has good short-term anti-cancer effects.

Key Points

? CT-guided MWA is efficient in treating musculoskeletal malignant tumours. ? This prospective pilot study showed MWA induces high percentages of tumour necrosis. ? MWA has good short-term anti-cancer effects. ? MWA has healing potential when lesions can be completely necrosed. ? CT-guided MWA under equimolar mixture of oxygen-nitrous oxide inhalation is well tolerated.

     

The orientation of the surgical epicondylar axis varies in varus and non-varus knees in the coronal plane

Purpose

To investigate the orientations of the surgical epicondylar axis (SEA) of varus and non-varus knees in the coronal plane.

Methods

One-hundred and sixty-two knees from 81 Chinese patients undergoing total knee arthroplasty (TKA) were retrospectively investigated. The angle between the medial side of the femoral mechanical axis and the SEA (MA-SEA), as well as the physiological valgus angle, was measured in the coronal plane using three-dimensional reconstruction. The joint line angle (JLA) and hip-knee-ankle angle (HKAA) were measured in long-leg weight-bearing radiographs. The mean of each parameter was compared between the varus (HKAA < 177.0°) and the non-varus knees (HKAA ≥ 177.0°) using an independent t test. Linear regression was used to assess the correlation between MA-SEA with JLA and HKAA.

Results

A total of 42 non-varus knees (6 valgus and 36 neutral knees) and 98 varus knees were measured, as 22 knees were abandoned due to unrecognizable bony landmarks. The mean MA-SEA and JLA were significantly larger in non-varus knees (both, p < 0.01). The mean physiological valgus angle was 5.9 ± 1.0° for Chinese TKA patients and was significantly larger in varus knees (p < 0.01). There was a strong positive correlation between the MA-SEA and JLA (R ² = 0.35, p < 0.05).

Conclusions

There were significant differences in the orientation of the SEA between varus and non-varus knees, which was strongly correlated with the orientation of the femoral joint line. These findings will enhance the current knowledge of knee anatomy and should prove useful for coronal alignment in TKA.

Level of evidence

III.