Computed tomographic angiography measures of coronary plaque in clinical trials: opportunities and considerations to accelerate drug translation

Atherosclerotic coronary artery disease (CAD) is the causal pathological process driving most major adverse cardiovascular events (MACE) worldwide. The complex development of atherosclerosis manifests as intimal plaque which occurs in the presence or absence of traditional risk factors. There are numerous effective medications for modifying CAD but new pharmacologic therapies require increasingly large and expensive cardiovascular outcome trials to assess their potential impact on MACE and to obtain regulatory approval. For many disease areas, nearly a half of drugs are approved by the U.S. Food & Drug Administration based on beneficial effects on surrogate endpoints. For cardiovascular disease, only low-density lipoprotein cholesterol and blood pressure are approved as surrogates for cardiovascular disease. Valid surrogates of CAD are urgently needed to facilitate robust evaluation of novel, beneficial treatments and inspire investment. Fortunately, advances in non-invasive imaging offer new opportunity for accelerating CAD drug development. Coronary computed tomography angiography (CCTA) is the most advanced candidate, with the ability to measure accurately and reproducibly characterize the underlying causal disease itself. Indeed, favourable changes in plaque burden have been shown to be associated with improved outcomes, and CCTA may have a unique role as an effective surrogate endpoint for therapies that are designed to improve CAD outcomes. CCTA also has the potential to de-risk clinical endpoint-based trials both financially and by enrichment of participants at higher likelihood of MACE. Furthermore, total non-calcified, and high-risk plaque volume, and their change over time, provide a causally linked measure of coronary artery disease which is inextricably linked to MACE, and represents a robust surrogate imaging biomarker with potential to be endorsed by regulatory authorities. Global consensus on specific imaging endpoints and protocols for optimal clinical trial design is essential as we work towards a rigorous, sustainable and staged pathway for new CAD therapies.

Relevance of CT for the detection of septic foci: diagnostic performance in a retrospective cohort of medical intensive care patients

AIM

To analyse the diagnostic yield of computed tomography (CT) in septic patients from a medical intensive care unit (ICU).

MATERIALS AND METHODS

A full-text search of the department's radiological information system (RIS) retrieved 227 body CT examinations undertaken to search for a septic focus in 2018 from medical ICU patients. CT reports were categorised according to the identified foci. Clinical and laboratory information was gathered. Data were analysed statistically using descriptive statistics, diagnostic test quality criteria, binomial tests and chi-square test.

RESULTS

A total of 227 CT examinations from 165 septic patients detected 264 foci, which were distributed as follows: 58.3% (n=154/264) chest, 26.5% (n=70/264) abdomen, 5.3% (n=14/264) genitourinary system, and 9.8% (n=26/264) other body regions. In 15.9% (n=36/227) no focus was identified on CT. Based on CT reports, 37.5% (n=99/264) of foci were graded as certain, 18.9% (n=50/264) as likely, and 15.9% (n=42/264) as possible infectious sources. Septic foci were detected using CT with 75.8% sensitivity (95% confidence interval [CI] 69.6-81.9%) and 59.46% specificity (95% CI 42.9-76.1%). The positive predictive value was 90.6% (95% CI 86-95.2%), with a negative predictive value of 32.4% (95% CI 21-43.8%).

CONCLUSION

The present results confirm that body CT is a suitable rule-in test for septic patients in medical intensive care, although it cannot reliably rule out a septic focus. Follow-up CT examinations may reveal a septic source in the further course of a patient's hospital stay.

Causal effect of tooth loss on depression: evidence from a population-wide natural experiment in the USA

AIMS

Depression severely affects people's health and well-being. Oral diseases have been suggested to be associated with depression, but so far, there is no causal evidence. This study aimed to identify the causal effect of tooth loss on depression among US adults in a natural experiment study.

METHODS

Instrumental variable analysis was conducted using data from 169 061 respondents born in 1940-1978 who participated in the 2006, 2008 or 2010 waves of the Behavioral Risk Factor Surveillance System (BRFSS). Random variation in tooth loss due to differential childhood exposure to drinking water fluoride was exploited as an instrument.

RESULTS

US adults who were exposed to drinking water fluoride in childhood had more remaining teeth, therefore providing a robust instrument (F = 73.4). For each additional tooth loss, depressive symptoms according to the eight-item Patient Health Questionnaire depression (PHQ-8) score increased by 0.146 (95% CI 0.008-0.284), and the probability of having clinical depression (PHQ ⩾10) increased by 0.81 percentage points (95% CI -0.12 to 1.73).

CONCLUSIONS

Tooth loss causally increased depression among US adults. Losing ten or more teeth had an impact comparable to adults with major depressive disorder not receiving antidepressant drugs.

Prognostic value of noninvasive combined anatomic/functional assessment by cardiac ct in patients with suspected coronary heart disease

Background

Noninvasive evaluation of patients with stable angina is preferable over invasive testing if it leads to similar patient outcome. The combination of coronary angiography and vasodilator challenge myocardial perfusion imaging by computed tomography allows fast, comprehensive assessment of patients with suspected coronary heart disease.

Purpose

To compare the long-term prognostic value of combined computed tomography angiography (CTA) and myocardial CT perfusion imaging (CTP) with invasive coronary angiography (ICA) and single photon emission tomography (SPECT) in patients with suspected hemodynamically significant coronary heart disease.

Methods

At 16 centres, 381 patients were followed for major adverse cardiac events (MACE) for the CORE320 study. All patients underwent coronary CTA, CTP, and SPECT before ICA. Prognostic performance according binary results (normal/abnormal) was assessed by 5-year major cardiovascular events (MACE) free survival and area under the receiver-operating-characteristic curve (AUC).

Results

Follow up beyond 2-years was available in 323 patients. MACE-free survival rate was greater among patients with normal combined CTA/CTP findings compared to ICA/SPECT: 85 vs. 80% (95% confidence interval [CI] for difference 0.1, 11.3) though event-free survival time was similar (4.54 vs. 4.37 years, 95% CI for difference: 0.03, 0.36). Abnormal results by combined CTA/CTP was associated with 3.83 years event-free survival vs. 3.66 years after abnormal combined ICA/SPECT (95% CI for difference: 0.05, 0.39, CI −1.0, 11.1) (Figure). Predicting MACE by AUC also was similar: 65 vs. 65 (difference 0.1; 95% CI: −4.6, 4.9). When MACE was restricted to death, myocardial infarction, or stroke, AUC for CTA/CTP was 66 vs. 61 by ICA/SPECT (difference 5.1; 95% CI: −7.1, 12.9).

Conclusions

Combined CTA/CTP yield similar 5-year prognostic performance as joined ICA/SPECT assessment in patients presenting with suspected coronary heart disease and thus may represent a fast, non-invasive alternative to the traditional diagnostic approach.

Figure 1. 5-year event-free survival

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): National Institutes of Health

Neural networks-based regularization for large-scale medical image reconstruction

In this paper we present a generalized Deep Learning-based approach for solving ill-posed large-scale inverse problems occuring in medical image reconstruction. Recently, Deep Learning methods using iterative neural networks (NNs) and cascaded NNs have been reported to achieve state-of-the-art results with respect to various quantitative quality measures as PSNR, NRMSE and SSIM across different imaging modalities. However, the fact that these approaches employ the application of the forward and adjoint operators repeatedly in the network architecture requires the network to process the whole images or volumes at once, which for some applications is computationally infeasible. In this work, we follow a different reconstruction strategy by strictly separating the application of the NN, the regularization of the solution and the consistency with the measured data. The regularization is given in the form of an image prior obtained by the output of a previously trained NN which is used in a Tikhonov regularization framework. By doing so, more complex and sophisticated network architectures can be used for the removal of the artefacts or noise than it is usually the case in iterative NNs. Due to the large scale of the considered problems and the resulting computational complexity of the employed networks, the priors are obtained by processing the images or volumes as patches or slices. We evaluated the method for the cases of 3D cone-beam low dose CT and undersampled 2D radial cine MRI and compared it to a total variation-minimization-based reconstruction algorithm as well as to a method with regularization based on learned overcomplete dictionaries. The proposed method outperformed all the reported methods with respect to all chosen quantitative measures and further accelerates the regularization step in the reconstruction by several orders of magnitude.

Impact of integrated district level mental health care on clinical and social outcomes of people with severe mental illness in rural Ethiopia: an intervention cohort study

AIM

There is limited evidence of the safety and impact of task-shared care for people with severe mental illnesses (SMI; psychotic disorders and bipolar disorder) in low-income countries. The aim of this study was to evaluate the safety and impact of a district-level plan for task-shared mental health care on 6 and 12-month clinical and social outcomes of people with SMI in rural southern Ethiopia.

METHODS

In the Programme for Improving Mental health carE, we conducted an intervention cohort study. Trained primary healthcare (PHC) workers assessed community referrals, diagnosed SMI and initiated treatment, with independent research diagnostic assessments by psychiatric nurses. Primary outcomes were symptom severity and disability. Secondary outcomes included discrimination and restraint.

RESULTS

Almost all (94.5%) PHC worker diagnoses of SMI were verified by psychiatric nurses. All prescribing was within recommended dose limits. A total of 245 (81.7%) people with SMI were re-assessed at 12 months. Minimally adequate treatment was received by 29.8%. All clinical and social outcomes improved significantly. The impact on disability (standardised mean difference 0.50; 95% confidence interval (CI) 0.35-0.65) was greater than impact on symptom severity (standardised mean difference 0.28; 95% CI 0.13-0.44). Being restrained in the previous 12 months reduced from 25.3 to 10.6%, and discrimination scores reduced significantly.

CONCLUSIONS

An integrated district level mental health care plan employing task-sharing safely addressed the large treatment gap for people with SMI in a rural, low-income country setting. Randomised controlled trials of differing models of task-shared care for people with SMI are warranted.

Antenatal depressive symptoms as a predictor of deterioration in perceived social support across the perinatal period: a four-wave cohort study in Turkey

BACKGROUND

In a perinatal cohort of women in urban and rural Turkey, we investigated associations between antenatal depressive symptoms and subsequent changes in perceived quality of key family relationships.

METHOD

Of 730 women recruited in their third trimester (94.6% participation), 578 (79.2%) were reassessed at a mean of 4.1 (s.d. = 3.3) months after childbirth, 488 (66.8%) were reassessed at 13.7 (s.d. = 2.9) months, and 448 (61.4%) at 20.8 (s.d. = 2.7) months. At all four examinations, self-reported quality of relationship with the husband, mother and mother-in-law was ascertained using the Close Persons Questionnaire with respect to emotional support, practical support and negative aspects of the relationship. Antenatal depressive symptoms were defined using the Edinburgh Postnatal Depression Scale. A range of covariates in mixed models was considered including age, education, number of children, family structure, physical health, past emotional problems and stressful life events.

RESULTS

Key findings were as follows: (i) reported emotional and practical support from all three relationships declined over time in the cohort overall; (ii) reported emotional support from the husband, and emotional and practical support from the mother-in-law, declined more strongly in women with antenatal depressive symptoms; (iii) associations between depressive symptoms and worsening spouse relationship were more pronounced in traditional compared with nuclear families.

CONCLUSIONS

Antenatal depressive symptoms predicted marked decline in the quality of key relationships over the postnatal period. This may account for some of the contemporaneous associations between depression and worse social support, and may compound the risk of perinatal depression in subsequent pregnancies.

Adapting the Bayley Scales of infant and toddler development in Ethiopia: evaluation of reliability and validity

BACKGROUND

There is a need for valid and reliable observational measures of early child development in low-income and middle-income country settings.

METHODS

The aims of the study were to adapt the Bayley Scales of Infant Development (Bayley III) for a rural Ethiopian setting and evaluate reliability and validity. The study was carried out between January 2008 and January 2009 in the Butajira demographic surveillance site, south central Ethiopia. The Bayley III was adapted to be socioculturally appropriate for a rural Ethiopian context. Nurses and high school graduates were trained in administration of the measure for 10 days. Inter-rater reliability was evaluated (n = 60). Content, construct and convergent validity was then examined on a population-based cohort of children at the ages of 30 (n = 440) and 42 months (n = 456). Mokken scale analysis was used to determine the scalability of items in unidimensional, hierarchical sub-scales. The mean score was compared by age of child and by stunting status (less than -2 z scores below the standard height-for-age).

RESULTS

The intra-class correlations between raters were above 0.90 for all sub-scales of the child development measure. Some scale items were not contextually relevant and showed poor scalability. However, the majority of items scaled onto the existing sub-scales of the international measure to form adequate-to-strong hierarchical scales with good internal consistency (Cronbach's α above 0.70 except for gross motor and expressive language sub-scales). Item-scale coefficients were good. The mean score of all sub-scales was significantly higher in the older group of children (33.02 higher total score; P < 0.001) and in the children who were stunted (total Bayley score 2.58 (95% confidence interval 0.07 to 5.10) points lower at 30 months and 3.87 (1.94 to 5.81) points lower at 42 months.

CONCLUSIONS

An adapted version of an international, observational measure of child development was found to be reliable, valid and feasible in a rural Ethiopian setting.

Immune response to enzyme replacement therapies in lysosomal storage diseases and the role of immune tolerance induction

The US Food and Drug Administration (FDA) and National Organization for Rare Disease (NORD) convened a public workshop titled "Immune Responses to Enzyme Replacement Therapies: Role of Immune Tolerance Induction" to discuss the impact of anti-drug antibodies (ADAs) on efficacy and safety of enzyme replacement therapies (ERTs) intended to treat patients with lysosomal storage diseases (LSDs). Participants in the workshop included FDA staff, clinicians, scientists, patients, industry, and advocacy group representatives. The risks and benefits of implementing prophylactic immune tolerance induction (ITI) to reduce the potential clinical impact of antibody development were considered. Complications due to immune responses to ERT are being recognized with increasing experience and lengths of exposure to ERTs to treat several LSDs. Strategies to mitigate immune responses and to optimize therapies are needed. Discussions during the workshop resulted in the identification of knowledge gaps and future areas of research, as well as the following proposals from the participants: (1) systematic collection of longitudinal data on immunogenicity to better understand the impact of ADAs on long-term clinical outcomes; (2) development of disease-specific biomarkers and outcome measures to assess the effect of ADAs and ITI on efficacy and safety; (3) development of consistent approaches to ADA assays to allow comparisons of immunogenicity data across different products and disease groups, and to expedite reporting of results; (4) establishment of a system to widely share data on antibody titers following treatment with ERTs; (5) identification of components of the protein that are immunogenic so that triggers and components of the immune responses can be targeted in ITI; and (6) consideration of early ITI in patients who are at risk of developing clinically relevant ADA that have been demonstrated to worsen treatment outcomes.

Antipsychotic exposure prior to acute myocardial infarction in patients with serious mental illness

OBJECTIVE

To investigate the association between acute myocardial infarction (AMI) and recent exposure to antipsychotic agents in people with serious mental illness (SMI), and modifying influences.

METHOD

A case-crossover design was applied using the Taiwan National Health Insurance Research Database (NHIRD) to compare the exposure frequency of antipsychotic agents within individuals of schizophrenia or bipolar disorder between 60-day case and control periods prior to their first AMI episode during 1996-2007.

RESULTS

A sample of 834 patients with incident AMI was analysed. AMI was significantly associated with more recent antipsychotic exposure in schizophrenia after adjustment (OR 1.87, 95% confidence interval 1.15-3.03) bipolar disorder (OR 1.06, 0.51-2.21). This association in schizophrenia was significantly stronger in men and in patients without previous diagnoses of cardiovascular risk factors.

CONCLUSION

These findings are consistent with a short-term risk effect of antipsychotic exposure on risk of AMI and identify potentially vulnerable groups. Further research is required to clarify underlying biological mechanisms.

Subjective cognitive complaints across the adult life span: a 14-year analysis of trends and associations using the 1993, 2000 and 2007 English Psychiatric Morbidity Surveys

BACKGROUND

Cognitive complaints are common in all age groups but most often researched in old age. We aimed to investigate prevalences and time trends over 14 years of subjective memory complaints (SMC) and subjective concentration complaints (SCC) in adults and investigate associations with mood disorders and cognitive function.

METHOD

Data from three English national mental health surveys carried out in 1993, 2000 and 2007 were analysed. SMC and SCC were measured using the Clinical Interview Schedule-Revised and cognitive function using the modified Telephone Interview for Cognitive Status.

RESULTS

Both SMC and SCC increased up to middle age and then declined, followed by a second rise in the very oldest age groups. Age-specific prevalence of both increased across survey years but relationships with mental health and cognitive outcomes were relatively stable.

CONCLUSIONS

Cognitive complaints are most common in middle age and have become more prevalent over time.

[Development of the situation of doctoral students in medicine: Results of two surveys at an interval of ten years (2001 and 2011)]

BACKGROUND AND OBJECTIVE

The topic medical dissertation is often discussed controversially without quantitative data in Germany. The aim of this survey was to analyze the situation of doctoral students in medicine again after ten years.

METHODS

Students at Charité - Berlin in their 11th to 14th semester completed an online survey about the progress and the support of their dissertations (n = 1081). The questionnaire included current and aborted dissertations.

RESULTS

The present evaluation had almost the same percentage of respondents (28 %) as in 2001 (31 %) and showed improvements in the preparation for scientific work by curricular courses (p < 0.001). 51 % were aware of the principles of good scientific practice in 2011, which was five times more than in 2001 (10 %, p < 0.001). The knowledge of the doctoral topics catalogue doubled in the same time (from 40 % to 81 %, p < 0.001). In addition the participants of the Charité graduate program felt better prepared for scientific work (p < 0.001). One third still criticized the insufficient funds for their doctoral projects. Another request was better training in statistics because 50 % received no statistical support during the pursue of their thesis.

CONCLUSION

The graduate program at Charité has been making a significant contribution towards improved preparation for scientific work and medical dissertations. However, there are still improvements necessary such as better financial support and statistical preparation of medical dissertations.

Study of the use of antidepressants for depression in dementia: the HTA-SADD trial--a multicentre, randomised, double-blind, placebo-controlled trial of the clinical effectiveness and cost-effectiveness of sertraline and mirtazapine

OBJECTIVE

Depression is common in dementia, causing considerable distress and other negative impacts. Treating it is a clinical priority, but the evidence base is sparse and equivocal. This trial aimed to determine clinical effectiveness of sertraline and mirtazapine in reducing depression 13 weeks post randomisation compared with placebo.

DESIGN

Multicentre, parallel-group, double-blind placebo-controlled randomised controlled trial of the clinical effectiveness of sertraline and mirtazapine with 13- and 39-week follow-up.

SETTING

Nine English old-age psychiatry services.

PARTICIPANTS

A pragmatic trial. Eligibility: probable or possible Alzheimer's disease (AD), depression (4+ weeks) and Cornell Scale for Depression in Dementia (CSDD) score of 8+.

EXCLUSIONS

clinically too critical (e.g. suicide risk); contraindication to medication; taking antidepressants; in another trial; and having no carer.

INTERVENTIONS

(1) Sertraline; (2) mirtazapine; and (3) placebo, all with normal care. Target doses: 150 mg of sertraline or 45 mg of mirtazapine daily.

MAIN OUTCOME MEASURES

OUTCOME

CSDD score. Randomisation: Allocated 1 : 1 : 1 through Trials Unit, independently of trial team. Stratified block randomisation by centre, with randomly varying block sizes; computer-generated randomisation. Blinding: Double blind: medication and placebo identical for each antidepressant. Referring clinicians, research workers, participants and pharmacies were blind. Statisticians blind until analyses completed.

RESULTS

Numbers randomised: 326 participants randomised (111 placebo, 107 sertraline and 108 mirtazapine).

OUTCOME

Differences in CSDD at 13 weeks from an adjusted linear-mixed model: mean difference (95% CI) placebo-sertraline 1.17 (-0.23 to 2.78; p = 0.102); placebo-mirtazapine 0.01 (-1.37 to 1.38; p = 0.991); and mirtazapine-sertraline 1.16 (-0.27 to 2.60; p = 0.112).

HARMS

Placebo group had fewer adverse reactions (29/111, 26%) than sertraline (46/107, 43%) or mirtazapine (44/108, 41%; p = 0.017); 39-week mortality equal, five deaths in each group.

CONCLUSIONS

This is a trial with negative findings but important clinical implications. The data suggest that the antidepressants tested, given with normal care, are not clinically effective (compared with placebo) for clinically significant depression in AD. This implies a need to change current practice of antidepressants being the first-line treatment of depression in AD. From the data generated we formulated the following recommendations for future work. (1) The secondary analyses presented here suggest that there would be value in carrying out a placebo-controlled trial of the clinical effectiveness and cost-effectiveness of mirtazapine in the management of Behavioural and Psychological Symptoms of Dementia. (2) A conclusion from this study is that it remains both ethical and essential for trials of new medication for depression in dementia to have a placebo arm. (3) Further research is required to evaluate the impact that treatments for depression in people with dementia can have on their carers not only in terms of any impacts on their quality of life, but also the time they spend care-giving. (4) There is a need for research into alternative biological and psychological therapies for depression in dementia. These could include evaluations of new classes of antidepressants (such as venlafaxine) or antidementia medication (e.g. cholinesterase inhibitors). (5) Research is needed to investigate the natural history of depression in dementia in the community when patients are not referred to secondary care services. (6) Further work is needed to investigate the cost modelling results in this rich data set, investigating carer burden and possible moderators to the treatment effects. (7) There is scope for reanalysis of the primary outcome in terms of carer and participant CSDD results.

Automatic vs semi-automatic global cardiac function assessment using 64-row CT

OBJECTIVE

Global cardiac function assessment using multidetector CT (MDCT) is time-consuming. Therefore we sought to compare an automatic software tool with an established semi-automatic method.

METHODS

A total of 36 patients underwent CT with 64 × 0.5 mm detector collimation, and global left ventricular function was subsequently assessed by two independent blinded readers using both an automatic region-growing-based software tool (with and without manual adjustment) and an established semi-automatic software tool. We also analysed automatic motion mapping to identify end-systole.

RESULTS

The time needed for assessment using the semi-automatic approach (12:12 ± 6:19 min) was reduced by 75-85% with the automatic software tool (unadjusted, 01:34 ± 0:29 min, adjusted, 02:53 ± 1:19 min; both p<0.001). There was good correlation (r=0.89; p<0.001) for the ejection fraction (EF) between the adjusted automatic (58.6 ± 14.9%) and the semi-automatic (58.0 ± 15.3%) approaches. Also the manually adjusted automatic approach led to significantly smaller limits of agreement than the unadjusted automatic approach for end-diastolic volume (±36.4 ml vs ±58.5 ml, p>0.05). Using motion mapping to automatically identify end-systole reduced analysis time by 95% compared with the semi-automatic approach, but showed inferior precision for EF and end-systolic volume.

CONCLUSION

Automatic function assessment using MDCT with manual adjustment shows good agreement with an established semi-automatic approach, while reducing the analysis by 75% to less than 3 min. This suggests that automatic CT function assessment with manual correction may be used for fast, comfortable and reliable evaluation of global left ventricular function.

[Muscle trauma in primary total hip arthroplasty depending on age, BMI, and surgical approach: minimally invasive anterolateral versus modified direct lateral approach]

BACKGROUND

Maximum preservation of periarticular musculature is essential for the success of total hip arthroplasty. A poorer functional outcome often occurs following total hip arthroplasty, especially in older and overweight patients and is presumed to have a muscular basis. Minimally invasive hip endoprosthetics for muscle-preserving implantation have now become established in orthopedic surgery.

METHODS

A primary hip endoprosthesis was implanted in a total of 39 patients using a transgluteal (modified direct-lateral, mDL, n=19) or anterolateral minimally invasive approach (ALMI, n=20). Magnetic resonance imaging was performed preoperatively as well as 3 and 12 months after the operation. Fatty atrophy (FA) of the gluteus medius muscle was evaluated as a function of body mass index (BMI), patient age and the influence of the access route.

RESULTS

In the overweight group a significantly higher FA of the gluteus medius muscle was found 3 and 12 months after the operation and a significantly higher grade FA using the standard access in contrast to the normal weight group. A significantly higher FA of the gluteus medius muscle was found in the older patient group 3 and 12 months postoperation as well as a significantly higher atrophy using the mDL access.

CONCLUSIONS

Muscle trauma is demonstrably reduced using a minimally invasive access, especially in older and overweight patients. In these patients there is also a substantially higher postoperative muscular atrophy after implantation of a prosthesis than in corresponding normal weight and younger patients. The higher vulnerability and poorer capacity for regeneration of periarticular musculature means that this patient group particularly profits from a minimally invasive access route.

Intra- and interobserver variability of magnetic resonance imaging for quantitative assessment of abductor and external rotator muscle changes after total hip arthroplasty

PURPOSE

Magnetic resonance imaging (MRI) is one of the most widely used noninvasive diagnostic modalities for musculoskeletal evaluation. We conducted a retrospective study to determine whether MRI of the hip joint abductor and external rotator muscles yields reproducible findings in patients after total hip arthroplasty (THA).

MATERIALS AND METHODS

MR images were obtained 12 months after THA in 10 patients and were analyzed by two independent, blinded observers. The images were analyzed on workstations with three-dimensional analysis capabilities. The readers evaluated the gluteus medius, gluteus minimus, and obturator externus muscles on the nonoperated side (NOS) and the THA side. For each of the three muscles, the readers analyzed the cross-sectional area, cross-sectional signal intensity, intensity in a region of interest (ROI), and volume on both sides.

RESULTS

Unlike intraobserver variability, interobserver variability showed significant differences between the measurements for some abductor and external rotator muscles, especially for volume (p<0.001-0.02) and cross-sectional area (p<0.001-0.05) analysis of the gluteus medius and minimus muscles on the THA side but also on the NOS. There were no differences in signal intensity in the ROI (p=0.29-0.83). The coefficients of variation (CoV) of all 4 parameters quantified were lower on the NOS (average, 5.9%) than on the THA side (average, 7.3%). Analysis of the gluteus minimus muscle volume showed both higher intraobserver (18.8%) and interobserver (13.9%) variability on the THA side.

CONCLUSION

MRI is an accurate and reliable test for evaluation of soft tissue structures in patients who have undergone THA. MRI evaluation of abductor muscles yields reproducible results on the THA side and on the NOS. Prosthesis artifacts limit evaluation of the gluteus minimus muscle on the THA side and cannot be recommended. Since interobserver variability was always higher than intraobserver variability, follow-up examinations should ideally be performed by the same reader in order to obtain clinically meaningful results.

Whole-heart 320-row computed tomography: reduction of radiation dose via prior coronary calcium scanning

PURPOSE

The whole heart can be scanned in one rotation using 320-row coronary computed tomography angiography (CCTA), which covers up to 16 cm. Since most hearts are smaller, the total radiation dose may be reduced by adjusting the CCTA range to the individual heart size defined on a low-dose calcium scan (CACS).

MATERIALS AND METHODS

Forty-five patients with suspected coronary artery disease (13 women, 32 men; mean 61 ± 10 years) underwent CCTA preceded by low-dose CACS on a 320-row scanner (Aquilion ONE, Toshiba; 0.35 s gantry rotation, 120 kV, 350 - 450 mA) with 16-cm z-axis coverage (120 kV, 150 mA). The subsequent CCTA was performed over an adjusted scan range calculated as the individual heart size on CACS (+ 1 cm above and below). The total radiation dose of 16-cm CACS and the individually adjusted CCTA was compared with that of a calculated single CCTA using full 16-cm z-axis coverage.

RESULTS

CCTA could be performed with a reduced scan length in the z-axis in all patients. None of the scans had to be performed over the whole range of 16 cm. The adjusted scan length was 14 cm in 2 patients, 12.8 cm in 3 patients, and 12 cm in 40 patients. The effective CCTA scan range was 12.1 ± 0.5 cm based on mean individual heart sizes of 9.6 ± 1.1 cm. The mean total effective radiation dose of the entire cardiac CT examination (individually adapted CCTA and CACS) was significantly smaller than the exposure calculated for 16-cm CCTA without CACS (8.5 ± 4.7 vs. 9.1 ± 6.0 mSv, p = 0.006). The dose reduction was most relevant in patients with heart rates above 65 beats/min (n = 10) in whom 2 or 3 heartbeats were necessary for CCTA (17.7 ± 6.5 vs. 21.1 ± 8.4 mSv, p = 0.001).

CONCLUSION

320-row CCTA with an individually adjusted scan range based on prior CACS significantly reduces the radiation exposure compared with full 16-cm CCTA.