Musculoskeletal magnetic resonance imaging findings support a common spectrum of giant cell arteritis and polymyalgia rheumatica.

OBJECTIVES: To investigate the proportion and distribution of contrast enhancement (CE) of musculoskeletal structures with MRI of the thorax/abdomen/pelvis in giant cell arteritis (GCA). METHODS: CE at 34 musculoskeletal sites was rated with a 4-point ordinal scale. Patients were divided into groups with/without glucocorticoid (GC) treatment and with/without symptoms of polymyalgia rheumatica (PMR). Two composite scores were created: an MRI-score, including seven sites and a Limited-MRI-score, including four sites. RESULTS: Retrospectively, 90 consecutive patients with GCA were included. The population included 54 and 36 patients with and without PMR symptoms, respectively, and 45 (50%) patients were receiving GCs at the time of MRI. CE was found in 90.7% of lumbar spines, 87.5% of the pelvis, 82.2% of shoulder girdles and in 95.6% at any site in patients without GCs. The proportion of patients without and with GCs with at least moderate enhancement was 91.1%/75.6% at ≥ 1-3, 75.6%/51.1% at ≥ 4-6 and 64.4%/28.9% at ≥ 7-9 sites. The mean difference between the proportion of pathological CE in patients with and without GCs was 27.4% for synovial sites and 18.3% for periarticular/musculotendinous sites. Both composite scores captured substantial differences between groups, correlation was very strong between scores. CONCLUSIONS: MRI shows CE of musculoskeletal structures typical of PMR in most patients with GCA, supporting the concept of "GCA-PMR Spectrum Disease". Changes are more frequent at periarticular/musculotendinous sites and in the presence of PMR symptoms. A clear response to GCs is evident, less so for periarticular/musculotendinous sites.

Response assessment after stereotactic body radiation therapy for spine and non-spine bone metastases: results from a single institutional study.

BACKGROUND: The use of stereotactic body radiation therapy (SBRT) for tumor and pain control in patients with bone metastases is increasing. We report response assessment after bone SBRT using radiological changes through time and clinical examination of patients. METHODS: We analyzed retrospectively oligo-metastatic/progressive patients with bony lesions treated with SBRT between 12/2008 and 10/2018, without in-field re-irradiation, in our institution. Radiological data were obtained from imaging modalities used for SBRT planning and follow-up purposes in picture archiving and communication system and assessed by two independent radiologists blind to the time of treatment. Several radiological changes were described. Radiographic response assessment was classified according to University of Texas MD Anderson Cancer Center criteria. Pain response and the neurological deficit were captured before and at least 6 months after SBRT. RESULTS: A total of 35 of the 74 reviewed patients were eligible, presenting 43 bone metastases, with 51.2% (n = 22) located in the vertebral column. Median age at the time of SBRT was 66 years (range 38-84) and 77.1% (n = 27) were male. Histology was mainly prostate (51.4%, n = 18) and breast cancer (14.3%, n = 5). Median total radiation dose delivered was 24 Gy (range 24-42), in three fractions (range 2-7), prescribed to 70-90% isodose-line. After a median follow-up of 1.8 years (range < 1-8.2) for survivors, complete or partial response, stable, and progressive disease occurred in 0%, 11.4% (n = 4), 68.6% (n = 24), and 20.0% (n = 7) of the patients, respectively. Twenty patients (57.1%) died during the follow-up time, all from disease progression, yet 70% (n = 14) from this population with local stable disease after SBRT. From patients who were symptomatic and available for follow-up, almost half (44.4%) reported pain reduction after SBRT. CONCLUSIONS: Eighty percent of the patients showed local control after SBRT for bone metastases. Pain response was favorable. For more accurate response assessment, comparing current imaging modalities with advanced imaging techniques such as functional MRI and PET/CT, in a prospective and standardized way is warranted. Trial registration Retrospectively registered.

Recurrence Rate After Wide Resection of Plantar Fibromatosis: A Case Series and Systematic Literature Review.

BACKGROUND: The aim was to assess the recurrence rate and clinical outcome after wide resection for plantar fibromatosis. METHODS: A total of 12 patients, 2 to 13 years after wide resection, were assessed for local and magnetic resonance imaging tomographic signs of recurrence at the clinical follow-up. In addition, a systematic review of the literature was conducted. RESULTS: After 7.8 years (2-13), 2 patients (17%) suffered a recurrence. At the last follow-up, median Foot Functional Index was 1 (0-66) and American Orthopaedic Foot and Ankle Society score was 95 (44-100). Six studies with 109 feet (92 patients) were included in the systematic review. The recurrence rate depends on the width of the resection: 67% after local resection, 42% after wide resection, and 27% after fasciectomy. CONCLUSION: In patients with symptomatic plantar fibromatosis, we recommend a wide resection or fasciectomy over a local resection because of the inferior recurrence rate. LEVELS OF EVIDENCE: Level IV: Retrospective case series.

Takayasu arteritis: Prevalence and clinical presentation in Switzerland.

OBJECTIVE: Takayasu arteritis (TAK) is a rare immune-mediated vasculitis of the aorta and its branches. Aims were to calculate prevalence and incidence in Switzerland, to assess disease activity and performance of MR-Angiography (MRA). METHODS: 31 patients were recorded in a database, 27 were followed prospectively up to 3 years. Prevalence was calculated based on data of the national statistical bureau. Disease activity was defined using the revised EULAR criteria. MRA depicted stenotic changes and aortic wall enhancement. RESULTS: A disease prevalence of 14.5/1.000.000 inhabitants and an incidence of 0.3/1.000.000 per year was calculated. Aortic wall enhancement was found in 10 patients while in clinical and serological remission. EULAR criteria missed 5 patients with disease activity with isolated elevations of ESR/CRP. Arterial stenosis did not change over time in 5 cases, it improved in 2 and increased in 7. At follow-up 16 patients were treated with tocilizumab, 11/16 in monotherapy, 5 patients were treatment-free, 25/27 stayed in remission. CONCLUSION: In addition to prevalence and incidence, our data show that MRA qualifies to detect subclinical disease activity, but, on the other hand, that EULAR criteria may miss disease activity in case of isolated elevation of ESR/CRP.

Magnetization-prepared 2 Rapid Gradient-Echo MRI for B1 Insensitive 3D T1 Mapping of Hip Cartilage: An Experimental and Clinical Validation.

Background Often used for T1 mapping of hip cartilage, three-dimensional (3D) dual-flip-angle (DFA) techniques are highly sensitive to flip angle variations related to B1 inhomogeneities. The authors hypothesized that 3D magnetization-prepared 2 rapid gradient-echo (MP2RAGE) MRI would help provide more accurate T1 mapping of hip cartilage at 3.0 T than would 3D DFA techniques. Purpose To compare 3D MP2RAGE MRI with 3D DFA techniques using two-dimensional (2D) inversion recovery T1 mapping as a standard of reference for hip cartilage T1 mapping in phantoms, healthy volunteers, and participants with hip pain. Materials and Methods T1 mapping at 3.0 T was performed in phantoms and in healthy volunteers using 3D MP2RAGE MRI and 3D DFA techniques with B1 field mapping for flip angle correction. Participants with hip pain prospectively (July 2019-January 2020) underwent indirect MR arthrography (with intravenous administration of 0.2 mmol/kg of gadoterate meglumine), including 3D MP2RAGE MRI. A 2D inversion recovery-based sequence served as a T1 reference in phantoms and in participants with hip pain. In healthy volunteers, cartilage T1 was compared between 3D MP2RAGE MRI and 3D DFA techniques. Paired t tests and Bland-Altman analysis were performed. Results Eleven phantoms, 10 healthy volunteers (median age, 27 years; range, 26-30 years; five men), and 20 participants with hip pain (mean age, 34 years ± 10 [standard deviation]; 17 women) were evaluated. In phantoms, T1 bias from 2D inversion recovery was lower for 3D MP2RAGE MRI than for 3D DFA techniques (mean, 3 msec ± 11 vs 253 msec ± 85; P < .001), and, unlike 3D DFA techniques, the deviation found with MP2RAGE MRI did not correlate with increasing B1 deviation. In healthy volunteers, regional cartilage T1 difference (109 msec ± 163; P = .008) was observed only for the 3D DFA technique. In participants with hip pain, the mean T1 bias of 3D MP2RAGE MRI from 2D inversion recovery was -23 msec ± 31 (P < .001). Conclusion Compared with three-dimensional (3D) dual-flip-angle techniques, 3D magnetization-prepared 2 rapid gradient-echo MRI enabled more accurate T1 mapping of hip cartilage, was less affected by B1 inhomogeneities, and showed high accuracy against a T1 reference in participants with hip pain. © RSNA, 2021.

Does increased acetabular depth affect safe infra-acetabular screw placement in acetabular fracture fixation?

BACKGROUND: Infra-acetabular screws enhance the fixation strength in acetabular fractures with separation of both columns. Placement without iatrogenic femoral head violation is challenging. PURPOSE: To assess the impact of the acetabular configuration, the patients' age and gender on safe infra-acetabulum screw insertion. METHODS: In 112 patients (69 females; mean age: 34 years, range 17-88; n = 200 hips), the lateral center-edge angle (LCE) was measured on radiographs. Using corresponding axial CT scans the residual distance from (the lateral border) of the screw to (the medial border of) the femoral head ("Screw-to-Femoral Head distance"; "RD_SFH") was determined. Statistical analysis was carried out using linear regression, multiple linear regression and normal distribution estimation. RESULTS: The mean (range) LCE angle was 30° (7°-51°) and the mean (range) "RD_SFH" was 5 mm (1-14 mm). The linear regression model shows a significant linear relation between LCE and "RD_SFH" with a slope parameter of - 0.15 (p value < 0.0001), the Pearson correlation between LCE and "RD_SFH" is - 0.56 (CI [- 0.71, [- 0.40]). Age did not have a significant impact on the relation between LCE and "RD_SFH" (p value 0.85). Compared to male patients, in females, the intercept is 4.62 mm (p value 0.0005) less, the slope parameter is 0.09 (p value 0.029) larger. CONCLUSION: The virtual possibility to place an infra-acetabular screw was given in all patients. An increasing depth of the acetabulum correlated with a decrease in residual distances. As hip joint cartilage thickness was not considered in measurements, intraoperative rule-out of screw mispositioning especially in deep acetabular sockets and females is still of utmost importance.

The Influence of Various Cerebral and Extracerebral Pathologies on Apparent Diffusion Coefficient Values in the Fetal Brain.

BACKGROUND AND PURPOSE: The changing MRI signal accompanying brain maturation in fetal brains can be quantified on apparent diffusion coefficient (ADC) maps. Deviations from the natural course of ADC values may reflect structural pathology. The purpose of this study was to determine the influence of fetal pathologies on the ADC values in different regions of the fetal brain and their evolution with increasing gestational age. METHODS: This was a retrospective study of 291 fetuses evaluated between the 14th and the 40th week of gestation using diffusion-weighted imaging (DWI). Fetuses with normal MRI findings but sonographically suspected pathology or fetuses with abnormalities not affecting the brain were analyzed in the control group and compared to fetuses suffering from different pathologies like hydrocephalus/ventriculomegaly, brain malformations, infections, ischemia/hemorrhage, diaphragmatic hernias, and congenital heart disease. Pairwise ADC measurements in each side of the white matter (WM) of the frontal, parietal, and occipital lobes, in the basal ganglia and the cerebellum, as well as a single measurement in the pons were performed and were plotted against gestational age. RESULTS: In the control group, brain maturation followed a defined gradient, resulting in lower ADC values in the most mature regions. Each disorder group experienced abnormal patterns of evolution of the ADC values over time deviating from the expected course. CONCLUSIONS: The ADC values in different regions of the fetal brain and their evolution with increasing gestational age are influenced by pathologies compromising the cerebral maturation.

Transfer of osteochondral shell autografts to salvage femoral head impaction injuries in hip trauma patients.

INTRODUCTION: Femoral head impaction defects are observed with variable severity, as a result of traumatic hip dislocations which can be caused by traffic accidents or seen in professional athletes amongst other mechanisms. Compression of the articular cartilage and the subchondral bone into the femoral head results in irregular articular surfaces influencing the outcome with predisposition to osteoarthritis, and being predictive for the need for delayed total hip replacement. This study reports the outcome after a minimum follow-up (FU) of five years in a consecutive series treated with transfer of osteochondral shell autografts in hips (TOSAH) from the head-neck junction into the defect using surgical hip dislocation. PATIENTS AND METHODS: Between 06/2007 and 03/2014 a series of twelve consecutive patients (mean age: 35yrs, range 18-53; median Injury Severity Score: 12, range 9-27) sustained a traumatic posterior hip dislocation in combination with acetabular and/or Pipkin fractures and were inter alia treated using TOSAH using surgical hip dislocation. Conversion to total hip replacement (THR) during FU was noted as failure. Patients were clinically (Merle d'Aubigné score) and radiographically assessed for occurrence of osteoarthritis (OA), avascular necrosis (AVN) and/or heterotopic ossification (HO) at a minimal follow-up of five years. RESULTS: Mean follow-up was 6.9 years (5.0-11.6). At five-year follow-up, we found a survivorship of 57.1% (95% Confidence interval {CI}, 46.7-100%). Four patients required conversion to a total hip replacement at 11, 16, 28 and 44 months respectively after the TOSAH procedure due to osteoarthritis progression. One patient required conversion to a total hip replacement 12 months after TOSAH procedure due to AVN. One patient was lost to follow-up after 2.7 years. The remaining six patients with preserved hips presented with a median Merle-d'Aubigné score of 16 points (range: 14-18) and no AVN. Two patients showed asymptomatic grade I osteoarthritis according to Tönnis at latest follow-up and three patients showed mild asymptomatic HO according to Brooker (Grade I-II). CONCLUSION: The presented technique can be used as a salvage procedure for severely injured hip joints and to preserve the hip joint at midterm with satisfying clinical and radiological outcomes.

Risk of relapse after discontinuation of tocilizumab therapy in giant cell arteritis.

OBJECTIVE: It is currently unknown how long GCA should be treated with tocilizumab. In the first randomized controlled trial, the biologic agent was stopped after 52 weeks. We therefore studied what proportion of patients relapsed, when relapses occurred and whether factors might predict relapse after tocilizumab treatment discontinuation. METHODS: All patients in the tocilizumab arm who had received a 52-week treatment were evaluated. In case of lasting remission, magnetic resonance angiography (MRA) was performed and sera were taken to search for biomarkers associated with subclinical disease activity. RESULTS: Seventeen of 20 patients randomized to the tocilizumab treatment arm were in lasting remission without any co-medication at week 52. Mean follow-up after study end was 28.1 months (range 17-44). Eight patients relapsed after a mean of 6.3 months (range 2-14) (six within the first 5 months, two patients at months 13 and 14, respectively). Relapsing patients were younger and showed more signs of mural enhancement in MRA compared with non-relapsing patients. MRA documented low-intensity vessel wall signals in all subjects. No morphological changes such as formation of aneurysm of aorta occurred. Biomarkers in sera did not indicate subclinical disease activity: levels of IL-6, MMP-3, soluble TNF receptor 2, soluble CD163, soluble intercellular adhesion molecule-1 and Pentraxin-3 did not differ from matched healthy controls. CONCLUSION: The data show that a 52-week treatment with tocilizumab induces a lasting remission that persists in half of the patients after treatment stop. None of the clinical, serological or MRA findings qualify to predict relapse. Remarkably, MRA revealed a persisting wall enhancement of the descending aorta.

Imaging appearance and distribution of intra-articular adhesions following open FAI surgery.

OBJECTIVES: To evaluate the appearance and distribution of intra-articular adhesions on direct MR arthrograms (MRA) in symptomatic patients after surgical hip dislocation (SHD) for the treatment of femoroacetabular impingement (FAI). METHODS: All 18 patients (19 hips) who underwent arthroscopic debridement for treatment of symptomatic adhesions after open surgery of FAI between 2003 and 2012 and that had a complete set of pre- and postoperative direct MRA were evaluated. On radial PD-w images, pre- and postoperative osseous alpha angles were measured. Signal intensity and degree of obliteration of the peripheral compartment of the hip joint were assessed circumferentially at each 'half-hour' position and quantified with the adhesion alpha angle (measured between a line connecting the most proximal appearance of adhesions on the femoral neck with the femoral head center and the femoral neck axis). Linear regression analysis was performed between the site of correction and adhesions. As a control group, all patients (9; 9 hips) that underwent revision surgery during the same time period in which adhesions were not the primary cause for revision were evaluated. RESULTS: Femoral adhesions primarily (47%) appeared as intermediate, complete obliterations correlating with the site of offset correction (R = 0.883, p < 0.001). Adhesion alpha angles were comparable to the pre-operative osseous alpha angles (21/24 positions, p > 0.05) and were greater than the postoperative osseous alpha angles (11/24 positions, p < 0.05). Most labral adhesions (83.2%) appeared as adjacent and correlated with the site of rim trimming (R = 0.777, p < 0.001). In the control group, the most common reason for revision surgery was persisting cam deformity (67%). The radiographic findings were confirmed intra-operatively. CONCLUSION: Intra-articular adhesions most commonly appear at the site of primary offset correction. Recurrent impingement due to scar tissue may be quantified with the adhesion alpha angle. MRA of the hip are suitable to distinguish between postoperative adhesions and other known causes for persisting symptoms.

Magnetic resonance angiography in giant cell arteritis: results of a randomized controlled trial of tocilizumab in giant cell arteritis.

Objective: To analyse magnetic resonance angiographic (MRA) vessel wall signals from a randomized controlled trial of tocilizumab (TCZ) to treat GCA. Methods: Participants were assigned in a 2:1 ratio to receive either TCZ + glucocorticoids (GCs) or placebo + GC infusions at 4-week intervals for 52 weeks. GCs were started at 1 mg/kg/day, then tapered to 0.1 mg/kg/day at week 12 and thereafter down to zero. Patients with initial positive MRA findings underwent control MRA at weeks 12 and 52. Vessel wall signals were scored from 0 (normal) to 3 (intense late enhancement). Outcomes were the number of patients with complete MRA remission at weeks 12 and 52, and changes in vasculitis score, vessel anatomy and atherosclerosis. Results: Of the 30 randomized participants, nine TCZ and two placebo patients had no vessel wall enhancement on initial MRA. At week 12, MRAs were performed in nine TCZ and four placebo patients (nine and three in clinical remission, respectively). Three (33%) TCZ patients showed normalization of vessel wall signals compared with one (25%) placebo patient. At week 52, there was additional MRA improvement in some TCZ patients, but one-third showed persistent or increased late vessel wall enhancement. There was no formation of aneurysms or stenosis and no increase in atherosclerosis. Conclusions: Although TCZ resulted in complete clinical and laboratory remission of GCA over 52 weeks, MRA signals in vessel walls normalized in only one-third of patients. Whether these signals are of prognostic importance remains to be determined.

Pleomorphic rhabdomyosarcoma with an impressive response to chemotherapy: case report and review of the literature.

PURPOSE: Pleomorphic rhabdomyosarcoma (RMS) represents a rare sarcoma subtype of the adult population. Due to its clinical characteristics, treatment is currently based on the guidelines for adult soft tissue sarcoma therapy. Hence, in the metastatic setting, doxorubicin-containing regimens are used in the sarcoma community, with limited treatment benefit. Scanty published data are available on the efficacy of systemic treatment. Whether treatment response and outcome of these patients could be improved by using pediatric protocols used typically in other RMS subtypes, like embryonal and alveolar RMS, is unclear. We report on an impressive effect of multiagent pediatric chemotherapy in an adult patient with metastatic pleomorphic RMS. METHODS: We present the case of a 70-year-old man with metastatic pleomorphic RMS of his left thigh. Systemic chemotherapy according to the VAC regimen (vincristine, actinomycin, cyclophosphamide) was initiated. Follow-up clinical and radiologic assessment demonstrated an impressive treatment response. RESULTS: Sixteen months after primary diagnosis, computed tomography scan shows no signs of tumor progression. CONCLUSIONS: Our case report emphasizes that multiagent systemic therapy according to pediatric protocols should be considered in adult patients with pleomorphic RMS.

A cost-effective surgical navigation solution for periacetabular osteotomy (PAO) surgery.

PURPOSE: To evaluate a low-cost, inertial sensor-based surgical navigation solution for periacetabular osteotomy (PAO) surgery without the line-of-sight impediment. METHODS: Two commercial inertial measurement units (IMU, Xsens Technologies, The Netherlands), are attached to a patient's pelvis and to the acetabular fragment, respectively. Registration of the patient with a pre-operatively acquired computer model is done by recording the orientation of the patient's anterior pelvic plane (APP) using one IMU. A custom-designed device is used to record the orientation of the APP in the reference coordinate system of the IMU. After registration, the two sensors are mounted to the patient's pelvis and acetabular fragment, respectively. Once the initial position is recorded, the orientation is measured and displayed on a computer screen. A patient-specific computer model generated from a pre-operatively acquired computed tomography scan is used to visualize the updated orientation of the acetabular fragment. RESULTS: Experiments with plastic bones (eight hip joints) performed in an operating room comparing a previously developed optical navigation system with our inertial-based navigation system showed no statistically significant difference on the measurement of acetabular component reorientation. In all eight hip joints the mean absolute difference was below four degrees. CONCLUSION: Using two commercially available inertial measurement units we show that it is possible to accurately measure the orientation (inclination and anteversion) of the acetabular fragment during PAO surgery and therefore to successfully eliminate the line-of-sight impediment that optical navigation systems have.

Radiation dose in pneumatic reduction of ileo-colic intussusceptions--results from a single-institution study.

BACKGROUND: Air enema under fluoroscopy is a well-accepted procedure for the treatment of childhood intussusception. However, the reported radiation doses of pneumatic reduction with conventional fluoroscopy units have been high in decades past. OBJECTIVE: To compare current radiation doses at our institution to past doses reported by others for fluoroscopic-guided pneumatic reduction of ileo-colic intussusception in children. MATERIALS AND METHODS: Since 2007 radiologists and residents in our department who perform reduction of intussusceptions have received a radiation risk training. We retrospectively analyzed the data of 45 children (5 months-8 years) who underwent a total of 48 pneumatic reductions of ileo-colic intussusception between 2008 and 2012. We analyzed data for screening time and dose area product (DAP) and compared these data to those reported up to and including the year 2000. RESULTS: Our mean screening time measured by the DAP-meter was 53.8 s (range 1-320 s, median 33.0 s). The mean DAP was 11.4 cGy ∙ cm(2) (range 1-145 cGy ∙ cm(2), median 5.45 cGy ∙ cm(2)). There was one bowel perforation, in a 1-year-old boy requiring surgical revision. Only three studies in the literature presented radiation exposure results on children who received pneumatic or hydrostatic reduction of intussusception under fluoroscopy. Screening times and dose area products in those studies, which were published in the 1990 s and in the year 2000, were substantially higher than those in our sample. CONCLUSION: Low-frequency pulsed fluoroscopy and other dose-saving keys as well as the radiation risk training might have helped to improve the quality of the procedure in terms of radiation exposure.

Accuracy of computed tomography angiography in the detection of pulmonary embolism in patients with high body weight.

BACKGROUND: The accuracy of CT pulmonary angiography (CTPA) in detecting or excluding pulmonary embolism has not yet been assessed in patients with high body weight (BW). METHODS: This retrospective study involved CTPAs of 114 patients weighing 75-99 kg and those of 123 consecutive patients weighing 100-150 kg. Three independent blinded radiologists analyzed all examinations in randomized order. Readers' data on pulmonary emboli were compared with a composite reference standard, comprising clinical probability, reference CTPA result, additional imaging when performed and 90-day follow-up. Results in both BW groups and in two body mass index (BMI) groups (BMI <30 kg/m(2) and BMI ≥ 30 kg/m(2), i.e., non-obese and obese patients) were compared. RESULTS: The prevalence of pulmonary embolism was not significantly different in the BW groups (P=1.0). The reference CTPA result was positive in 23 of 114 patients in the 75-99 kg group and in 25 of 123 patients in the ≥ 100 kg group, respectively (odds ratio, 0.991; 95% confidence interval, 0.501 to 1.957; P=1.0). No pulmonary embolism-related death or venous thromboembolism occurred during follow-up. The mean accuracy of three readers was 91.5% in the 75-99 kg group and 89.9% in the ≥ 100 kg group (odds ratio, 1.207; 95% confidence interval, 0.451 to 3.255; P=0.495), and 89.9% in non-obese patients and 91.2% in obese patients (odds ratio, 0.853; 95% confidence interval, 0.317 to 2.319; P=0.816). CONCLUSION: The diagnostic accuracy of CTPA in patients weighing 75-99 kg or 100-150 kg proved not to be significantly different.

Comparison of dual-energy subtraction and electronic bone suppression combined with computer-aided detection on chest radiographs: effect on human observers' performance in nodule detection.

OBJECTIVE: The objective of our study was to compare the effect of dual-energy subtraction and bone suppression software alone and in combination with computer-aided detection (CAD) on the performance of human observers in lung nodule detection. MATERIALS AND METHODS: One hundred one patients with from one to five lung nodules measuring 5-29 mm and 42 subjects with no nodules were retrospectively selected and randomized. Three independent radiologists marked suspicious-appearing lesions on the original chest radiographs, dual-energy subtraction images, and bone-suppressed images before and after postprocessing with CAD. Marks of the observers and CAD marks were compared with CT as the reference standard. Data were analyzed using nonparametric tests and the jackknife alternative free-response receiver operating characteristic (JAFROC) method. RESULTS: Using dual-energy subtraction alone (p = 0.0198) or CAD alone (p = 0.0095) improved the detection rate compared with using the original conventional chest radiograph. The combination of bone suppression and CAD provided the highest sensitivity (51.6%) and the original nonenhanced conventional chest radiograph alone provided the lowest (46.9%; p = 0.0049). Dual-energy subtraction and bone suppression provided the same false-positive (p = 0.2702) and true-positive (p = 0.8451) rates. Up to 22.9% of lesions were found only by the CAD program and were missed by the readers. JAFROC showed no difference in the performance between modalities (p = 0.2742-0.5442). CONCLUSION: Dual-energy subtraction and the electronic bone suppression program used in this study provided similar detection rates for pulmonary nodules. Additionally, CAD alone or combined with bone suppression can significantly improve the sensitivity of human observers for pulmonary nodule detection.

Diagnostic accuracy of pulmonary CT angiography at low tube voltage: intraindividual comparison of a normal-dose protocol at 120 kVp and a low-dose protocol at 80 kVp using reduced amount of contrast medium in a simulation study.

OBJECTIVE: The purpose of this study was to simulate pulmonary emboli (PE) and image quality at low tube energy and reduced contrast material volume in normal-dose pulmonary CT angiography (CTA) images and to analyze the diagnostic accuracy with normal- and low-dose pulmonary CTA. MATERIALS AND METHODS: Normal-dose pulmonary CTA examinations using 120 kVp and 100 mL of contrast material in 10 patients with no PE were retrospectively selected. The image characteristics of an 80-kVp low-dose pulmonary CTA protocol (patient exposure reduction, 57%) with 75 mL of contrast material were simulated. Four different sets of filling defects were computer simulated in identical locations in each normal-dose and corresponding low-dose examination, equaling 783 PE in 40 normal-dose and 40 low-dose datasets. Ten normal-dose and 10 low-dose examinations contained no emboli and were used as controls. The 100 pulmonary CTA studies were randomly assessed by three readers blinded to PE location and image quality. The results were assessed by nonparametric tests and Student t tests. RESULTS: No difference was found between the CT protocols in terms of sensitivity, specificity, and positive and negative diagnostic likelihood ratios at all ramification levels of the pulmonary arteries (p = 0.343-1). The overall sensitivity and specificity with the normal and simulated low-dose protocols were 79.9% versus 81.3% and 98.0% versus 98.2% (p = 0.444 and 0.702), respectively. The diagnostic confidence (2.81 ± 0.39 vs 2.77 ± 0.47; p = 0.297) and overall image quality (3.92 ± 0.52 vs 3.83 ± 0.54; p = 0.216) were similar at 120 kV and 80 kV. CONCLUSION: The intraindividual comparison of diagnostic accuracy with normal-dose and simulated low-dose pulmonary CTA protocols revealed no difference under experimental conditions.

Nonlinear three-dimensional noise filter with low-dose CT angiography: effect on the detection of small high-contrast objects in a phantom model.

PURPOSE: To study the effect of a nonlinear noise filter on the detection of simulated endoleaks in a phantom with 80- and 100-kVp multidetector computed tomographic (CT) angiography. MATERIALS AND METHODS: An aortic aneurysm phantom, including iodinated endoleaks, was constructed. Multidetector CT angiography with use of 80-, 100-, and 120-kVp tube voltages was performed for simulated intermediate-sized and large patients (estimated body weights, 72-85 kg and 118-142 kg, respectively). Images obtained with 80 and 100 kVp were postprocessed by using a nonlinear noise filter. CT images containing 1152 endoleaks and images with no endoleaks were randomized and independently analyzed by three radiologists blinded to the location of the endoleaks. Diagnostic confidence and image quality were rated by using subjective scales. Analysis of variance was used for statistical assessment. RESULTS: In simulated intermediate-sized patients, energy reduction from 120 to 100 kVp and from100 to 80 kVp did not decrease image quality when images with reduced kilovoltage were filtered (P = .2692 and P > .99, respectively). Readers detected more endoleaks on the filtered 100-kVp images than on the nonfiltered images in simulated large patients (83 vs 75 lesions, P = .041). The number of detected endoleaks and the confidence rate were similar at 100 kVp with a filter and at 120 kVp in simulated large patients (P = .339 and P = .211, respectively). CONCLUSION: In a phantom, the nonlinear noise filter can prevent decreased image quality with use of 80- and 100-kVp abdominal multidetector CT angiography at a wide range of simulated body weights and may facilitate a better detection rate of endoleaks in heavy patients.