The lithospheric-to-lower-mantle carbon cycle recorded in superdeep diamonds.

The transport of carbon into Earth's mantle is a critical pathway in Earth's carbon cycle, affecting both the climate and the redox conditions of the surface and mantle. The largest unconstrained variables in this cycle are the depths to which carbon in sediments and altered oceanic crust can be subducted and the relative contributions of these reservoirs to the sequestration of carbon in the deep mantle1. Mineral inclusions in sublithospheric, or 'superdeep', diamonds (derived from depths greater than 250 kilometres) can be used to constrain these variables. Here we present oxygen isotope measurements of mineral inclusions within diamonds from Kankan, Guinea that are derived from depths extending from the lithosphere to the lower mantle (greater than 660 kilometres). These data, combined with the carbon and nitrogen isotope contents of the diamonds, indicate that carbonated igneous oceanic crust, not sediment, is the primary carbon-bearing reservoir in slabs subducted to deep-lithospheric and transition-zone depths (less than 660 kilometres). Within this depth regime, sublithospheric inclusions are distinctly enriched in 18O relative to eclogitic lithospheric inclusions derived from crustal protoliths. The increased 18O content of these sublithospheric inclusions results from their crystallization from melts of carbonate-rich subducted oceanic crust. In contrast, lower-mantle mineral inclusions and their host diamonds (deeper than 660 kilometres) have a narrow range of isotopic values that are typical of mantle that has experienced little or no crustal interaction. Because carbon is hosted in metals, rather than in diamond, in the reduced, volatile-poor lower mantle2, carbon must be mobilized and concentrated to form lower-mantle diamonds. Our data support a model in which the hydration of the uppermost lower mantle by subducted oceanic lithosphere destabilizes carbon-bearing metals to form diamond, without disturbing the ambient-mantle stable-isotope signatures. This transition from carbonate slab melting in the transition zone to slab dehydration in the lower mantle supports a lower-mantle barrier for carbon subduction.

[Osteoarthritis classifications : Modification proposal for the criteria of Kellgren and Vallotton]. / Arthrose-Klassifikationen : Modifizierungsvorschlag für die Kriterien nach Kellgren und Vallotton.

BACKGROUND: In imaging diagnostics, classification schemes are very common. As far as osteoarthritis is concerned, the Kellgren classification is the most popular. However, the Kellgren classification, which has been used for more than 50 years, is based on nonspecific criteria; thus, high interobserver variability has been reported. In addition, the Kellgren classifications have not been coordinated with magnetic resonance imaging (MRI)-based classification schemes, e.g., Vallotton. AIM: In this paper, we present some modifications concerning the criteria for both the Kellgren classification and its comparison with the MRI-based Vallotton classification. METHODS: The current surgical and imaging classifications and the precision of the nomenclature are analyzed. X­ray and MRI findings are compared. RESULTS: Suggestions for both a modification of the Kellgren classification as far as the criteria are concerned and a hierarchy (ranking) of X­ray and MRI findings to make clinical decisions more valuable are proposed. CONCLUSION: These proposed modifications (Kellgren and ranking) would be helpful for routine reporting and allow for better interobserver reliability, in particular for special reports (e.g. consultations, expert opinions, advanced diagnostics).

[Muscular injuries in the inguinal region including apophyseal injuries]. / Muskelverletzungen der Leistenregion einschließlich apophysärer Verletzungen.

BACKGROUND: Muscular and apophyseal injuries in the inguinal region are a common cause of groin pain in athletes. PURPOSE: Frequently occurring muscular and apophyseal injuries in the groin region are described. MATERIAL AND METHODS: Fundamental studies and expert recommendations are discussed. Examination protocols for routine clinical practice are presented. RESULTS: The exact diagnosis and classification of muscular or apophyseal injuries in the inguinal region are the basic prerequisites for the initiation of a targeted treatment and thus crucial for the return to sport time. These injuries are occurring with increasing frequency in both professional and recreational sports. CONCLUSION: In addition to the clinical examination and the history of the course of the injury, MRI plays an important role in the evaluation of muscular and apophyseal injuries in the inguinal region.

Incidence and severity of malreduction of the tibiofibular syndesmosis following surgical treatement of displaced ankle fractures and impact on the function -Clinical study and MRI evaluation.

PURPOSE: To compare tibiofibular reduction quality in different types of operatively treated ankle fractures and the impact on clinical and functional outcome at mid-term follow-up. PATIENTS AND METHODS: One hundred patients with an acute ankle fracture who had undergone open reduction and internal fixation were included. Eighty-eight patients who suffered from ligamentous ankle injury with neither fracture nor syndesmotic lesions served as a control group. Tibiofibular alignment was measured on MR images in all 188 patients. In case of tibiofibular malreduction tibiotalar positioning was determined as well. Clinical and functional outcome was assessed using the AOFAS hindfoot score as well as the SF-36. RESULTS: No tibiofibular malreduction was found in type Weber B fractures, irrespective of syndesmotic instability followed by syndesmotic screw placement, as compared to the control group. A significant tibiofibular malreduction was detected in bimalleolar/trimalleolar/dislocated type Weber B fractures and in isolated type Weber C fractures with syndesmotic screw, in comparison to the control group. Tibiotalar displacement could not be detected. Clinical and functional outcome analysis revealed no significant differences between the treatment groups. CONCLUSION: Three-dimensional imaging may improve tibiofibular malreduction visualization in bimalleolar/trimalleolar/dislocated type Weber B fractures and in isolated type Weber C fractures with syndesmotic transfixation. The clinical impact of improving tibiofibular positioning remains highly questionable since there was no correlation between tibiofibular alignment and the clinical outcome at mid-term follow-up.

MDCT in suspected lumbar spine fracture: comparison of standard and reduced dose settings using iterative reconstruction.

AIM: To compare standard (SD-) and reduced-dose computed tomography (RD-CT) in combination with iterative reconstruction (IR) in emergency patients with suspected lumbar spine fracture. MATERIAL AND METHODS: Forty emergency patients with suspected lumbar spinal disorder who underwent RD-CT and 40 body mass index-matched patients undergoing SD-CT were enrolled in this retrospective study. Raw data for RD-CT were reconstructed using two increasing IR levels (IRL) 4 and 6, while SD-CT was reconstructed with IRL3. Two radiologists assessed image quality, image noise, and reader confidence in interpreting findings of spinal fractures in a blinded manner. RESULTS: Effective radiation dose was reduced by 50% using RD-CT. Overall subjective image quality (SIQ) was high for both protocols and slightly superior in the RD-CT protocol for both IRL compared to SD-CT. The detection rate of spinal disorders was high for both protocols with a high interobserver agreement. CONCLUSION: RD-CT with higher levels of IR results in substantial dose reduction of 50% in lumbar spine CT while maintaining an excellent subjective image quality resulting in a high diagnostic confidence.

Worth a second look: outcomes of patients with initial finding of regular renal tissue in CT-guided renal tumor biopsies.

INTRODUCTION AND OBJECTIVE: Renal tumor biopsy is recommended for histological diagnosis of radiologically indeterminate renal masses, to select patients with small-renal masses for surveillance approaches, before ablative treatments and to confirm metastatic spread of renal cell cancer (RCC), according to the EAU guidelines. We aimed to determine outcomes of patients with suspicious renal masses with initial finding of regular renal tissue in renal tumor biopsies. METHODS: Retrospective database analysis of 101 patients undergoing CT-guided-, percutaneous renal tumor biopsies in local anesthesia. RESULTS: In 23/101 patients, histopathologic evaluation of the biopsies showed regular renal tissue. Of these, two patients underwent simultaneous radiofrequency ablation (RFA), 2/23 underwent radical nephrectomy, despite negative biopsy because of radiological suspicious aspect. Overall, 12 patients underwent a second set of biopsies due to persistent clinical suspicion. Of these, five were diagnosed with RCC: three clear cell renal cell carcinoma (ccRCC) and two papillary renal cell carcinoma (pRCC). Benign tumours were found in two patients. A lymphoma was found in two patients. In 3/12 patients, also the second set of biopsies showed regular renal tissue. CONCLUSION: An unsuspicious histology in CT-guided renal tumor biopsy does not preclude patients with suspicious renal masses from being diagnosed with malignancies.

Comparison of T2* relaxation times of articular cartilage of the knee in elite professional football players and age-and BMI-matched amateur athletes.

OBJECTIVE: Recent investigation has underlined the potential of quantitative MR imaging to be used as a complementary tool for the diagnosis of cartilage degeneration at an early state. The presented study analyses T2* relaxation times of articular cartilage of the knee in professional athletes and compares the results to age- and BMI (Body Mass Index)-matched healthy amateur athletes. MATERIALS AND METHODS: 22 professional football players and 22 age- and BMI-matched individuals were underwent knee Magnetic Resonance Imaging (MRI) at 3T including qualitative and quantitative analysis. Qualitative analysis included e.g. meniscal tears, joint effusion and bone edema. For quantitative analysis T2* (22 ET: 4.6-53.6ms) measurements in 3D data acquisition were performed. Deep and superficial layers of 22 predefined cartilage segments were analysed. All data sets were postprocessed using a dedicated software tool. Statistical analysis included Student t-test, confidence intervals and a random effects model. RESULTS: In both groups, T2* relaxation times were significantly higher in the superficial compared to the deep layers (p<0.001). Professional athletes had significantly higher relaxation times in eight superficial and three deep cartilage layers in the predefined cartilage segments (p<0.05). Highly significant differences were found in the weight-bearing segments of the lateral superficial femoral condyle (p<0.001). CONCLUSION: Elevated T2* values in cartilage layers of professional football players compared to amateur athletes were noted. The effects seem to predominate in superficial cartilage layers.

Performance of cone-beam computed tomography and multidetector computed tomography in diagnostic imaging of the midface: A comparative study on Phantom and cadaver head scans.

PURPOSE: To compare multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) regarding radiation, resolution, image noise, and image quality. METHODS: CBCT and 256-MDCT were compared based on three scan protocols: Standard-dose (≈24 mGy), reduced-dose (≈9 mGy), and low-dose (≈4 mGy). MDCT images were acquired in standard- and high-resolution mode (HR-MDCT) and reconstructed using filtered back projection (FBP) and iterative reconstruction (IR). Spatial resolution in linepairs (lp) and objective image noise (OIN) were assessed using dedicated phantoms. Image quality was assessed in scans of 25 cadaver heads using a Likert scale. RESULTS: OIN was markedly higher in FBP-MDCT when compared to CBCT. IR lowered the OIN to comparable values in standard-mode MDCT only. CBCT provided a resolution of 13 lp/cm at standard-dose and 11 lp/cm at reduced-dose vs. 11 lp/cm and 10 lp/cm in HR-MDCT. Resolution of 10 lp/cm was observed for both devices using low-dose settings. Quality scores of MDCT and CBCT did not differ at standard-dose (CBCT, 3.4; MDCT, 3.3-3.5; p > 0.05). Using reduced- and low-dose protocols, CBCT was superior (reduced-dose, 3.2 vs. 2.8; low dose, 3.0 vs. 2.3; p < 0.001). CONCLUSION: Using the low-dose protocol, the assessed CBCT provided better objective and subjective image quality and equality in resolution. Similar image quality, but better resolution using CBCT was observed at higher exposure settings. KEY POINTS: • The assessed CBCT device provided better image quality at lower doses. • Objective and subjective image quality were comparable using higher exposure settings. • CBCT showed superior spatial resolution in standard-dose and reduced-dose settings. • Modern noise-reducing tools are used in CBCT devices currently. • MDCT should be preferred for assessment of soft-tissue injuries and oncologic imaging.

Critical analysis of a simplified Fuhrman grading scheme for prediction of cancer specific mortality in patients with clear cell renal cell carcinoma--Impact on prognosis.

INTRODUCTION AND OBJECTIVES: The traditional 4-tiered Fuhrman grading system (FGS) is widely accepted as histopathological classification for clear cell renal cell carcinoma (ccRCC) and has shown prognostic value. As intra- and inter-observer agreement are sub-optimal, simplified 2- or 3-tiered FGSs have been proposed. We aimed to validate these simplified 2- or 3-tiered FGSs for prediction of cancer-specific mortality (CSM) in a large study population from 2 European tertiary care centers. METHODS: We identified and followed-up 2415 patients with ccRCC who underwent radical or partial nephrectomy in 2 European tertiary care centers. Univariable and multivariable analyses and prognostic accuracy analyses were performed to evaluate the ability of several simplified FGSs (i.e. grades I + II vs., grades III + IV, grades I + II vs. grade III and grade IV) to predict CSM. RESULTS: Independent predictor status in multivariate analyses was proved for the simplified 2-tiered FGS (high-grade vs. low-grade), for the simplified 3-tiered FGS (grades I + II vs. grade III and grade IV) as well as for the traditional 4-tiered FGS. The prognostic accuracy of multivariable models of 77% was identical for all tested models. Prognostic accuracy of the model without FG was 75%. CONCLUSIONS: A simplified 2- or 3-tiered FGS could predict CSM as accurate as the traditional 4-tiered FGS in a large European study population. Application of new simplified 2- or 3-tiered FGS may reduce inter-observer-variability and facilitate clinical practice without compromising the ability to predict CSM in ccRCC patients after radical or partial nephrectomy.

Buprenorphine: a new player in neonatal withdrawal syndrome.

OBJECTIVE: To study the incidence and patient characteristics of Neonatal Abstinence Syndrome (NAS) in infants who were born to opioid addicted mothers and required NICU admission over the three year period. STUDY DESIGN: From 2009 to 2011, data of infants admitted in WVUH NICU with history of maternal drug exposure were extracted and reviewed. Infants born to mothers treated with buprenorphine (BPN) and those with methadone (MTD) were compared. RESULTS: Incidence of drug exposure infants significantly increased in 2011. BPN exposure infants increased substantially while the number of MTD exposure infants did not significantly change. Eighty-one percent of those MTD exposure infants required drug treatment for NAS compared to 26% of BPN exposure infants. CONCLUSION: Significant increase in opioid exposure infants with NAS was observed in our unit in 2011. Although, the incidence of BPN exposure with NAS increased significantly, only 25% of them required drug treatment.

Association between diabetes, diabetes treatment and risk of developing endometrial cancer.

BACKGROUND: A growing body of evidence suggests that diabetes is a risk factor for endometrial cancer incidence. However, most of these studies used case-control study designs and did not adjust for obesity, an established risk factor for endometrial cancer. In addition, few epidemiological studies have examined the association between diabetes treatment and endometrial cancer risk. The objective of this study was to assess the relationships among diabetes, diabetes treatment and endometrial cancer risk in postmenopausal women participating in the Women's Health Initiative (WHI). METHODS: A total of 88 107 postmenopausal women aged 50-79 years who were free of cancer and had no hysterectomy at baseline were followed until date of endometrial cancer diagnosis, death, hysterectomy or loss to follow-up, whichever came first. Endometrial cancers were confirmed by central medical record and pathology report review. Multivariate Cox proportional hazards regression models were used to estimate hazard ratios (HRs) (95% confidence interval (CI)) for diagnosis of diabetes and metformin treatment as risk factors for endometrial cancer. RESULTS: Over a mean of 11 years of follow-up, 1241 endometrial cancers developed. In the primary analysis that focused on prevalent diabetes at enrolment, compared with women without diabetes, women with self-reported diabetes, and the subset of women with treated diabetes, had significantly higher risk of endometrial cancer without adjusting for BMI (HR=1.44, 95% CI: 1.13-1.85 for diabetes, HR=1.57, 95% CI: 1.19-2.07 for treated diabetes). However after adjusting for BMI, the associations between diabetes, diabetes treatment, diabetes duration and the risk of endometrial cancer became non-significant. Elevated risk was noted when considering combining diabetes diagnosed at baseline and during follow-up as time-dependent exposure (HR=1.31, 95% CI: 1.08-1.59) even after adjusting for BMI. No significant association was observed between metformin use and endometrial cancer risk. CONCLUSIONS: Our results suggest that the relationship observed in previous research between diabetes and endometrial cancer incidence may be largely confounded by body weight, although some modest independent elevated risk remains.

Intraindividual evaluation of the influence of iterative reconstruction and filter kernel on subjective and objective image quality in computed tomography of the brain.

OBJECTIVES: To intraindividually evaluate the potential of 4th generation iterative reconstruction (IR) on brain CT with regard to subjective and objective image quality. METHODS: 31 consecutive raw data sets of clinical routine native sequential brain CT scans were reconstructed with IR level 0 (= filtered back projection), 1, 3 and 4; 3 different brain filter kernels (smooth/standard/sharp) were applied respectively. Five independent radiologists with different levels of experience performed subjective image rating. Detailed ROI analysis of image contrast and noise was performed. Statistical analysis was carried out by applying a random intercept model. RESULTS: Subjective scores for the smooth and the standard kernels were best at low IR levels, but both, in particular the smooth kernel, scored inferior with an increasing IR level. The sharp kernel scored lowest at IR 0, while the scores substantially increased at high IR levels, reaching significantly best scores at IR 4. Objective measurements revealed an overall increase in contrast-to-noise ratio at higher IR levels, which was highest when applying the soft filter kernel. The absolute grey-white contrast decreased with an increasing IR level and was highest when applying the sharp filter kernel. All subjective effects were independent of the raters' experience and the patients' age and sex. CONCLUSION: Different combinations of IR level and filter kernel substantially influence subjective and objective image quality of brain CT.

Impact of a 4th generation iterative reconstruction technique on image quality in low-dose computed tomography of the chest in immunocompromised patients.

PURPOSE: To determine the image quality of an iterative reconstruction (IR) technique in low-dose MDCT (LDCT) of the chest of immunocompromised patients in an intraindividual comparison to filtered back projection (FBP) and to evaluate the dose reduction capability. MATERIALS AND METHODS: 30 chest LDCT scans were performed in immunocompromised patients (Brilliance iCT; 20-40 mAs; mean CTDIvol: 1.7 mGy). The raw data were reconstructed using FBP and the IR technique (iDose4™, Philips, Best, The Netherlands) set to seven iteration levels. 30 routine-dose MDCT (RDCT) reconstructed with FBP served as controls (mean exposure: 116 mAs; mean CDTIvol: 7.6 mGy). Three blinded radiologists scored subjective image quality and lesion conspicuity. Quantitative parameters including CT attenuation and objective image noise (OIN) were determined. RESULTS: In LDCT high iDose4™ levels lead to a significant decrease in OIN (FBP vs. iDose7: subscapular muscle 139.4 vs. 40.6 HU). The high iDose4™ levels provided significant improvements in image quality and artifact and noise reduction compared to LDCT FBP images. The conspicuity of subtle lesions was limited in LDCT FBP images. It significantly improved with high iDose4™ levels (> iDose4). LDCT with iDose4™ level 6 was determined to be of equivalent image quality as RDCT with FBP. CONCLUSION: iDose4™ substantially improves image quality and lesion conspicuity and reduces noise in low-dose chest CT. Compared to RDCT, high iDose4™ levels provide equivalent image quality in LDCT, hence suggesting a potential dose reduction of almost 80%.

[Multidetector computed tomography of urolithiasis: technique and results]. / Multidetektor-Computertomografie der Urolithiasis: Technik und Ergebnisse.

The diagnosis of acute urolithiasis results from unenhanced multidetector computed tomography (MDCT). This test analyses the functional and anatomical possibility for passing an ureteral calculi, the localization and dimension of which are important parameters for further therapy. Alternatively chronic urolithiasis could be ruled out by magnetic resonance urography (MRU). MRU is the first choice especially in pregnant women and children because of radiation hygiene. Enhanced MDCT must be emphasized as an alternative to intravenous urography (IVU) for diagnosis of complex drainage of urine and suspected disorder of the involved kidney. This review illustrates the principles of different tests and the clinical relevance thereof.

Pulmonary manifestation of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients: initial findings with multidetector computed tomography.

OBJECTIVE: To describe initial multidetector computed tomographic (MDCT) findings of novel swine-origin influenza A (H1N1) virus (S-OIV) infection in immunocompromised patients and to evaluate whether or not identification of certain abnormalities can help predict patients who are at risk for a severe clinical course. SUBJECTS AND METHODS: This retrospective study included 13 patients with confirmed S-OIV infection suffering from an underlying immunodeficiency or who were receiving immunosuppressive therapy. All patients underwent MDCT of the thorax due to respiratory distress. All data were read by two independent radiologists who described the type and pattern of opacities, distribution and extent of the abnormalities observed. Adverse outcome measures were defined as acute respiratory distress syndrome with the need for mechanical ventilation, extracorporeal membrane oxygenation or death. RESULTS: MDCT revealed pulmonary manifestations in 12 (92%) of 13 individuals. Six (50%) patients showed an adverse outcome with development of acute respiratory distress syndrome, 4 of these died. The most common findings were ground-glass opacities (10/12; 83%) and pulmonary consolidation (7/12; 58%) predominantly with a bilateral distribution. Reticular pattern and a tree-in-bud appearance were found in 3/12 (25%), respectively. Bilateral opacities with extensive involvement of the lung parenchyma were most predictive of a severe clinical course. CONCLUSION: The MDCT scan in immunocompromised patients with confirmed S-OIV infection frequently revealed pulmonary abnormalities, which included ground-glass opacities and consolidations. Therefore, prediction of an adverse clinical outcome could be made in patients with MDCT findings demonstrating bilateral extensive consolidations, often combined with ground-glass opacities.

Quantitative assessment of bone marrow attenuation values at MDCT: an objective tool for the detection of bone bruise related to occult sacral insufficiency fractures.

OBJECTIVES: To prove the feasibility of using Hounsfield attenuation values at MDCT to detect bone bruises related to sacral insufficiency fractures. METHODS: Twenty-two patients with acute sacrum trauma and no fracture findings at MDCT were included in our prospective study. Two observers independently reviewed CTs regarding visual signs of bone bruises in 132 defined regions of the sacral alae. Interobserver agreement was tested by κ statistics. Subsequently, HU values were obtained in the same regions, and attenuation differences between the two sides were calculated. Validity and reliability were assessed by intraclass correlation coefficient and Bland-Altman analysis. HU differences were subjected to ROC curve analysis to determine sensitivity, specificity, PPV and NPV. MRI served as standard reference. RESULTS: MRI revealed 19 regions with bone bruises and associated sacral insufficiency fractures. HU measurements demonstrated good validity and reliability (r = 0.989). ROC curve analysis exhibited an ideal cutoff value of 35.7 HU density difference between affected and non-affected regions. Visual evaluation revealed moderate agreement (κ = 0.48); diagnostic accuracy was inferior to objective evaluation. CONCLUSIONS: Assessment of differences in bone marrow density by HU measurements is an objective and reliable tool for detection of bone bruises associated with occult sacral insufficiency fractures. KEY POINTS : • Bone bruising is associated with occult sacral insufficiency fractures. • Assessment of differences in bone marrow CT attenuation appears valid and reliable. • Comparative HU measurements of bone marrow allow detection of bone bruises. • Comparative HU measurements have high specificity and negative predictive values. • Comparative HU measurements may make further diagnostic workup with MRI unnecessary.

Post-biopsy arteriovenous fistula in transplant kidney: treatment with superselective transcatheter embolisation.

PURPOSE: To evaluate the technical success and therapeutic effect of superselective embolisation of arteriovenous fistulas in renal allografts. MATERIALS AND METHODS: Between 2000 and 2009, 20 patients underwent angiography of 24 AV fistulas (AVF) following percutanous biopsy of the transplanted kidney. Indications for angiography were the diagnosis of AVF by ultrasound and in addition persistent or worsening transplant renal function, or haematuria. Superselective catheterisation of the fistula was performed with a coaxial microcatheter and microcoils were used to occlude the fistula. To assess the short-term effect of embolisation, serum creatinine values were evaluated before embolisation, in the first week after embolisation and after a period of minimum 42 days after the procedure. RESULTS: Angiography identified a single AVF in 16 patients and two AVFs in 4 patients. In 19 patients, successful embolisation was achieved without complications. In one patient, a second session was needed to embolise the AVF completely. The mean serum creatinine level of all patients with embolisation dropped significantly (p=0.0014) from 4.4 mg/dl (range: 1.4-11.6 mg/dl, standard deviation: 3.0) before embolisation to 2.7 mg/dl after embolisation (range: 1.0-7.0mg, standard deviation: 1.8). No patient showed an increase in serum creatinine. Long-term outcomes of the renal allograft revealed a well-functioning allograft in 19/20 patients. One patient returned to haemodialysis due to acute rejection. CONCLUSION: Superselective transcatheter embolisation is a safe and highly effective treatment for AVFs in renal allografts. Renal function was improved in the majority of patients.

256-MSCT image acquisition with sequential axial scans: evaluation of image quality and resolution in a phantom study.

PURPOSE: Evaluation of image quality and resolution of varying sequential axial scan protocols utilizing two resolution phantoms with a 256-MSCT scanner. MATERIALS AND METHODS: Sequential axial scans were performed on a z-axis and an axial-plane resolution phantom with varying acquisition and reconstruction parameters. Two independent observers evaluated the image quality and resolution, and analyzed quantitative image quality parameters and radiation doses. RESULTS: The best image quality and resolution were achieved with an activated z-flying focal spot (zFFS) and overlapping reconstruction. With an activated zFFS, image degradation was significantly minimized in marginal or overlapping zones of the beam, but the maximum effective detector width was reduced to 82 % and 75 %, respectively depending on the field of view. With a deactivated zFFS, the effective detector width was not restricted, but the image quality decreased and the artifacts increased as the collimation increased. CONCLUSION: For sequential axial CT data acquisition with multi-planar image reformation, the zFFS technique is crucial to achieve the best image quality and resolution. Major advantages are minimized image degradation and increased spatial resolution along the z-axis, but the zFFS reduces the maximum effective detector width.

Age-related incidence of pulmonary embolism and additional pathologic findings detected by computed tomography pulmonary angiography.

OBJECTIVE: To compare the incidence of pulmonary embolism (PE) and additional pathologic findings (APF) detected by computed tomography pulmonary angiography (CTPA) according to different age-groups. MATERIALS AND METHODS: 1353 consecutive CTPA cases for suspected PE were retrospectively reviewed. Patients were divided into seven age groups: ≤29, 30-39, 40-49, 50-59, 60-69, 70-79 and ≥80 years. Differences between the groups were tested using Fisher's exact or chi-square test. A p-value<0.0024 indicated statistical significance when Bonferroni correction was used. RESULTS: Incidence rates of PE ranged from 11.4% to 25.4% in different age groups. The three main APF were pleural effusion, pneumonia and pulmonary nodules. No significant difference was found between the incidences of PE in different age groups. Furthermore, APF in different age groups revealed no significant differences (all p-values>0.0024). CONCLUSION: The incidences of PE and APF detected by CTPA reveal no significant differences between various age groups.