Evolution of imaging findings, laboratory and functional parameters in rheumatoid arthritis patients after one year of treatment with anti-TNF-α agents.

OBJECTIVES: To investigate the efficacy and safety of anti-TNF-α agent treatment compared to non-biologic DMARDs in rheumatoid arthritis patients. METHODS: 82 consecutive patients, 29 males, 53 females, aged 42-79, diagnosed with RA and suitable for anti-TNF-α treatment composed two study groups: 42 with pre-existing rheumatoid arthritis-related interstitial lung disease (RA-ILD) and 40 without RA-ILD. Respective control groups consisted of 44 patients with pre-existing RA-ILD and 44 patients without RA-ILD, treated with non-biologic DMARDs. All patients underwent chest high resolution computed tomography (HRCT), pulmonary function tests (PFTs) and peripheral blood biomarkers at baseline and after one year of treatment. RESULTS: There was a significant decrease of air trapping extent and bronchial wall thickening after treatment in RA-ILD and RA-non ILD study groups (p<0.05). This was accompanied by a statistically significant improvement of maximum mid-expiratory flow (MMEF75-25), RV and RV/TLC in both study groups (p<0.05). In the RA-ILD study group ILD extent scores remained unchanged after anti-TNF-α treatment. None of the RA-non ILD group developed new-onset ILD. In both RA-ILD and RA-non ILD control groups, HRCT findings and PFTs did not differ significantly at the one-year follow-up study. Methotrexate (MTX) regression analysis showed in both RA-ILD study and control groups a negative correlation between MTX dose and ILD extent score at one-year and between MTX dose and air trapping extent at baseline and after one year of treatment. CONCLUSIONS: Anti-TNF-α treatment, in contrast to non-biologic DMARDs, there was an improvement of small airways disease. There was no new-onset ILD or exacerbation of preexisting-ILD, especially in patients treated with anti-TNF-α agents, supporting the efficacy and favourable safety profile of this treatment in RA patients.

MR imaging of spleen in beta-thalassemia major.

PURPOSE: Splenomegaly and splenic siderosis are well-known findings in beta-thalassemia major. We explored the relation between splenic size, splenic and hepatic siderosis in transfusion-dependent beta-thalassemic patients, assessed by MR imaging. MATERIALS AND METHODS: Abdominal MR imaging studies of 47 consecutive thalassemic patients and 10 healthy subjects, used as controls, were retrospectively reviewed. The signal intensity ratios of spleen and liver to the right paraspinous muscle (S/M, L/M, respectively) were calculated on T1, intermediate, and T2*-weighted gradient-echo sequences, splenic volume was estimated on axial images and serum ferritin levels were recorded. RESULTS: Decreased S/M on all MR sequences was displayed in 36 patients. Six patients presented with normal S/M on all MR sequences and 5 patients displayed splenic hypointensity only on T2* sequence. No correlation between S/M and L/M was found whereas both L/M and S/M correlated with serum ferritin (P < 0.03). Splenic volume correlated to L/M (P < 0.05) but not to S/M values. CONCLUSION: In transfusion-dependent patients with beta-thalassemia, iron deposition in spleen cannot be predicted by the degree of hepatic siderosis, whereas splenomegaly relates to liver, but not splenic, iron overload. MR imaging can be a valuable tool in elucidating iron kinetics.

Eye-lens bismuth shielding in paediatric head CT: artefact evaluation and reduction.

BACKGROUND: CT scans of the brain, sinuses and petrous bones performed as the initial imaging test for a variety of indications have the potential to expose the eye-lens, considered among the most radiosensitive human tissues, to a radiation dose. There are several studies in adults discussing the reduction of orbital dose resulting from the use of commercially available bismuth-impregnated latex shields during CT examinations of the head. OBJECTIVE: To evaluate bismuth shielding-induced artefacts and to provide suggestions for optimal eye-lens shielding in paediatric head CT. MATERIALS AND METHODS: A bismuth shield was placed over the eyelids of 60 consecutive children undergoing head CT. Images were assessed for the presence and severity of artefacts with regard to eye-shield distance and shield wrinkling. An anthropomorphic paediatric phantom and thermoluminescence dosimeters (TLDs) were used to study the effect of eye lens-to-shield distance on shielding efficiency. RESULTS: Shields were tolerated by 56/60 children. Artefacts were absent in 45% of scans. Artefacts on orbits, not affecting and affecting orbit evaluation were noted in 39% and 14% of scans, respectively. Diagnostically insignificant artefacts on intracranial structures were noted in 1 case (2%) with shield misplacement. Mean eye-lens-to-shield distance was 8.8 mm in scans without artefacts, and 4.3 mm and 2.2 mm in scans with unimportant and diagnostically important artefacts, respectively. Artefacts occurred in 8 out of 9 cases with shield wrinkling. Dose reduction remained unchanged for different shield-to-eye distances. CONCLUSION: Bismuth shielding-related artefacts occurring in paediatric head CT are frequent, superficial and diagnostically insignificant when brain pathology is assessed. Shields should be placed 1 cm above the eyes when orbital pathology is addressed. Shield wrinkling should be avoided.

Comparison between two-point and four-point methods for quantification of apparent diffusion coefficient of normal liver parenchyma and focal lesions. Value of normalization with spleen.

PURPOSE: To compare two quantification techniques of apparent diffusion coefficient (ADC), both in normal liver parenchyma and focal lesions, and to investigate any potential value of normalization. MATERIALS AND METHODS: Fifty-six consecutive patients underwent MRI examination of the liver, including a single shot spin-echo echo planar imaging diffusion sequence with four b-values (0, 50, 500 and 1000s/mm(2)). ADC maps were reconstructed based on a two-point method (b-values: 500 and 1000s/mm(2)) and a four-point method (b-values: 0, 50, 500 and 1000s/mm(2)). Comparison of absolute ADC measurements of the liver, benign and malignant focal lesions was performed between the two- and four-point techniques. The same analysis was done on normalized ADC values (absolute ADC values divided by spleen ADC values). RESULTS: The difference between mean two-point and four-point ADC values of normal liver (absolute: 1.237x10(-3), 1.615x10(-3)mm(2)/s, normalized: 1.40, 1.52, respectively) was statistically significant (p<0.0001 and p=0.0061). Significantly higher absolute ADC values of benign and malignant lesions were recorded with the four-point method (2.860x10(-3) and 1.307x10(-3)mm(2)/s) over the two-point method (2.243x10(-3), and 1.011x10(-3)mm(2)/s) (p<0.0001 in both) while the same differences in normalized values were proven statistically non-significant for benign lesions (p=0.788) and statistically significant for malignant lesions (p=0.015). Both differences in absolute and normalized ADC values of benign versus malignant lesions based on two- and four-point methods were found to be significant (p<0.0001). CONCLUSION: ADC quantification of the liver may be performed with a two-point method (b-values of 500 and 1000s/mm(2)), while normalization of ADC measurements with the spleen is not further improving lesion characterization.

Crohn's disease lymphadenopathy: MR imaging findings.

PURPOSE: To assess mesenteric lymph nodes in patients with different Crohn's disease subtypes identified on MR Enteroclysis. MATERIALS AND METHODS: Thirty-four patients, categorized into three different Crohn's disease subgroups, underwent MR Enteroclysis. A high resolution coronal true FISP sequence with fat saturation was applied to assess mesenteric lymph node anatomic distribution, size and shape. Their enhancement ratio (ER) was calculated by dividing signal intensity of each node to signal intensity of nearby vessel on T1 weighted FLASH images, acquired 75 s after intravenous administration of gadolinium. A one-way analysis of variance statistical test was applied to investigate any significant differences regarding mean ER among different disease subgroups. RESULTS: Two hundred and eighty-three mesenteric lymph nodes were assessed, 231 in patients with active inflammatory (AI) disease, 36 in patients with fibrostenotic (FS) and 16 in patients with fistulizing/perforating (FP) disease. Maximum and minimum diameters were 3.2 and 0.3 cm, respectively. 75% of the lymph nodes presented with an oval shape. The majority were identified as being ileocolic (34%) and paracolic (31%). AI subgroup lymph nodes presented with the highest mean ER (0.783+/-0.17) followed by FP (0.706+/-0.1) and FS subgroup (0.652+/-0.17) lymph nodes. The differences in mean values of ER of mesenteric lymph nodes between AI and FS subtypes were statistically significant (p<0.0001), while mean ER between nodes of FP and the other two subtypes did not present statistically significant differences. CONCLUSION: ER of mesenteric lymph nodes identified on MR Enteroclysis may vary across different subtypes of Crohn's disease. Such differences may be valuable in clinical practice.

Preliminary experience with cutting balloon angioplasty for iliac artery in-stent restenosis.

PURPOSE: To report our preliminary experience using cutting balloon angioplasty (CBA) in symptomatic iliac artery in-stent restenosis (ISR). METHODS: Fourteen cases of hemodynamically significant iliac artery ISR (4 common and 10 external) were treated in 12 men (mean age 64 years, range 55-75). Of the 14 stents involved, 8 were balloon-expandable models and 6 were self-expanding. All patients had symptomatic deterioration of at least 1 clinical category over an average period of 50.2 months (range 6-120) post stenting. The mean length of ISR was 11.9 mm (range 2-48), and the average stenosis was 75.4% (range 52%-98%). Nine ISR lesions were focal (<10 mm), 4 were diffuse (>10 mm), and 1 extended outside the stent margins. RESULTS: CBA was performed after conventional angioplasty failure in 7 lesions and as a primary treatment method in 7 lesions. Single (9 focal lesions) or multiple overlapping (5 diffuse or proliferative lesions) inflations were performed using 6-x10-mm (1 lesion), 7-x10-mm (3 lesions), and 8-x10-mm (10 lesions) devices. There was 1 contained rupture treated with a covered stent. In the remainder of the cases, the cutting balloons allowed successful treatment without further stent implantation. During a mean follow-up of 23.6 months (range 12-60), no patient showed clinical deterioration, and no recurrent ISR was detected with color duplex. CONCLUSION: CBA shows high immediate technical and midterm clinical success in symptomatic iliac artery ISR.

Stereological estimation of left-ventricular volumetric and functional parameters from multidetector-row computed tomography data.

This study aims to optimize the stereological method for estimating left-ventricular (LV) parameters from retrospectively electrocardiography-gated 16-row MDCT and to compare stereological estimations with those by MRI. MDCT was performed in 17 consecutive patients with known or suspected coronary disease. Stereological measurements based on point counting were optimized by determining the appropriate distance between grid points. LV parameters were evaluated by standard CT analysis using a semi-automatic segmentation method. Two independent observers evaluated the reproducibility of the stereological method. End-diastolic volume (EDV) and end-systolic volume (ESV) estimations with a coefficient of error below 5% were obtained in a mean time of 2.3 +/- 0.5 min with a point spacing of 25 and 15 pixels, respectively. The intra- and interobserver variability for estimating LV parameters was 2.6-4.4 and 4.9-8.2%, respectively. MRI estimations were highly correlated with those by standard CT analysis (R > 0.82) and stereology (R > 0.84). Stereological method significantly overestimated EDV and ESV compared to MRI (EDV: P = 0.0011; ESV: P = 0.0013), whereas for stroke volume (SV) and ejection fraction (EF), no difference was observed (P > 0.05). For standard CT analysis and MRI, significant differences were found except for SV and EF (EDV: P = 0.0008; ESV: P = 0.0004; EF: P = 0.051; SV: P = 0.064). The time-efficient optimized stereological method enables the reproducible evaluation of LV function from MDCT.

Migratory azygos vein: a case report.

We report a case of a "migrating" azygos vein developing after an abrupt spinal deformity adjacent to the azygos arch. A woman with a previously identified azygos lobe had a follow-up chest computed tomography that demonstrated the azygos vein dislocated medially to the fissure in its usual mediastinal position. The azygos lobe was intact. The woman had developed kyphosis angled at the level of the T4 vertebra, where the azygos vein arches anteriorly.

Late migration of two covered biliary stents through a spontaneous bilioenteric fistula in a patient with malignant biliary obstruction.

We report a case of simultaneous late migration of two ePTFE-FEP covered biliary endoprostheses (Viabil, W.L. Gore, Flagstaff, AZ, USA) that were percutaneously implanted for the treatment of malignant obstructive jaundice. The first Viabil covered stent was placed successfully without any evidence of dislocation or other complication during follow-up. Occlusion of the stent occurred 4 months later and was treated with the placement of a second stent of the same type. Thirteen months later the patient became symptomatic. Percutaneous transhepatic cholangiography (PTC) revealed the presence of a choledocho-duodenal fistula and the disappearance of the two endoprostheses previously implanted. A third metallic stent was then percutaneously positioned through the bilioenteric fistula. The computed tomography scan that followed for the detection of the metallic bodies did not reveal the dislocated metallic stents. Stent migration is a well-known complication of uncovered metallic stents, though Viabil stent migration is assumed to be most unlikely to happen due to the stent's anchoring barbs. Furthermore, the stent had already been tightly fixed by tumor over- and ingrowth, as recognized in previous imaging. This is a very unusual case, describing the disappearance of two metallic foreign bodies encapsulated by tumor.

Respiratory gated diffusion-weighted imaging of the liver: value of apparent diffusion coefficient measurements in the differentiation between most commonly encountered benign and malignant focal liver lesions.

The purpose of this study was to measure apparent diffusion coefficient values of normal liver parenchyma and focal liver lesions utilizing a respiratory gated diffusion sequence with multiple b-values and to investigate whether apparent diffusion coefficient (ADC) measurements may be utilized to characterize and differentiate between malignant and benign focal hepatic lesions. Thirty-eight consecutive patients underwent MRI of the liver including diffusion-weighted imaging (DWI). A single-shot echo planar imaging sequence was applied in coronal orientation with multiple b-values (0, 50, 500, 1,000 s/mm2) and respiratory gating. ADC values were recorded on corresponding maps utilizing region of interest measurements in patients with benign (group A), malignant (group B) focal lesions and liver parenchyma (group C). Statistical analysis was applied to check whether differences in mean ADC values were significant (p<0.05). No focal lesions were detected in 11 patients, with a mean ADC value (CI 95%) of liver parenchyma 1.25x10(-3) mm2/s (1.21x10(-3) mm2/s-1.29x10(-3) mm2/s). Differences in mean ADC of liver parenchyma between group A and B were not significant (p=0.054, 1.30x10(-3) mm2/s and 1.31x10(-3) mm2/s, respectively). Mean ADC value (95% CI) of 22 benign lesions found in 18 patients was 2.55x10(-3) mm2/s (2.35x10(-3) mm2/s-2.74x10(-3) mm2/s), while the mean ADC value (95% CI) of 16 malignant lesions recorded in 9 patients was 1.04x10(-3) mm2/s (0.9x10(-3) mm2/s-1.17x10(-3) mm2/s). The difference between mean ADC values of benign and malignant focal lesions was statistically significant (p<0.0001). Respiratory gated diffusion-weighted imaging in the liver is technically feasible. Apparent diffusion coefficient measurements can be useful in differentiating malignant from benign focal liver lesions.

White paper of the European Society of Radiology (ESR) and the European Association of Nuclear Medicine (EANM) on multimodality imaging.

New multimodality imaging systems bring together anatomical and molecular information and require the competency and accreditation of individuals from both radiology and nuclear medicine. This paper sets out the positions and aspirations of the European Society of Radiology (ESR) and the European Association of Nuclear Medicine (EANM) working together on an equal and constructive basis for the future benefit of both specialties. ESR and EANM recognise the importance of coordinating working practices for multimodality imaging systems and that undertaking the radiology and nuclear medicine components of imaging with hybrid systems requires different skills. It is important to provide adequate and appropriate training in the two disciplines in order to offer a proper service to the patient using hybrid systems. Training models are proposed with the overall objective of providing opportunities for acquisition of special competency certification in multimodality imaging. Both organisations plan to develop common procedural guidelines and recognise the importance of coordinating the purchasing and management of hybrid systems to maximise the benefits to both specialties and to ensure appropriate reimbursement of these examinations. European multimodality imaging research is operating in a highly competitive environment. The coming years will decide whether European research in this area manages to defend its leading position or whether it falls behind research in other leading economies. Since research teams in the member states are not always sufficiently interconnected, more European input is necessary to create interdisciplinary bridges between research institutions in Europe and to stimulate excellence. ESR and EANM will work with the European Institute for Biomedical Imaging Research (EIBIR) to develop further research opportunities across Europe. European Union grant-funding bodies should allocate funds to joint research initiatives that encompass clinical research in diagnostic imaging in conjunction with research in mechanical and electronic engineering, informatics and biostatistics, and epidemiology.

White paper of the European Association of Nuclear Medicine (EANM) and the European Society of Radiology (ESR) on multimodality imaging.

INTRODUCTION: New multimodality imaging systems bring together anatomical and molecular information and require the competency and accreditation of individuals from both nuclear medicine and radiology. AIM: This paper sets out the positions and aspirations of the European Association of Nuclear Medicine (EANM) and the European Society of Radiology (ESR) working together on an equal and constructive basis for the future benefit of both specialties. DISCUSSION: EANM and ESR recognise the importance of coordinating working practices for multimodality imaging systems and that undertaking the nuclear medicine and radiology components of imaging with hybrid systems requires different skills. It is important to provide adequate and appropriate training in the two disciplines in order to offer a proper service to the patient using hybrid systems. Training models are proposed with the overall objective of providing opportunities for acquisition of special competency certification in multimodality imaging. Both organisations plan to develop common procedural guidelines and recognise the importance of coordinating the purchasing and management of hybrid systems to maximise the benefits to both specialties and to ensure appropriate reimbursement of these examinations. European multimodality imaging research is operating in a highly competitive environment. The coming years will decide whether European research in this area manages to defend its leading position or whether it falls behind research in other leading economies. Since research teams in the Member States are not always sufficiently interconnected, more European input is necessary to create interdisciplinary bridges between research institutions in Europe and to stimulate excellence. EANM and ESR will work with the European Institute for Biomedical Imaging Research (EIBIR) to develop further research opportunities across Europe. RECOMMENDATION: European Union grant-funding bodies should allocate funds to joint research initiatives that encompass clinical research in diagnostic imaging in conjunction with research in mechanical and electronic engineering, informatics and biostatistics, and epidemiology.

ePTFE/FEP-covered metallic stents for palliation of malignant biliary disease: can tumor ingrowth be prevented?

PURPOSE: To determine the application and clinical effectiveness of ePTFE/FEP-covered metallic stents for palliation of malignant biliary disease, and to evaluate the efficiency of stent coverage in preventing tumor ingrowth. METHODS: During a 3-year period, 36 patients with malignant obstructive jaundice were treated with ePTFE/FEP-covered stents, with or without proximal side holes. The stricture was located in the lower common bile duct (CBD) in 18 cases, the upper CBD in 9, the lower common hepatic duct (CHD) in 6, and the upper CHD in 3 patients. RESULTS: Thirty-seven covered stents were percutaneously implanted. The technical success rate was 97%. Reintervention was required in 6 cases. The 30-day mortality rate was 40%, not procedure-related. Mean survival was 128 days. Primary patency rates were 100%, 55.5%, and 25% at 3, 6, and 12 months, respectively, while the assisted patency rate was 100% at 12 months. Stents without side holes had higher primary patency rates compared with those with side holes, where occlusion was always due to tumor ingrowth. Tumor ingrowth did not occur in the completely covered stents. No stent dysfunction due to sludge incrustation was found. Complications were 1 case of arterial laceration that occurred during percutaneous transhepatic cholangiography, and a subcapsular hematoma and 1 case of bile peritonitis, that both occurred during primary stenting. No complications followed the secondary stenting technique. CONCLUSION: ePTFE/FEP-covered metallic stents are safe and effective for palliation of malignant biliary disease. The presence of the ePTFE/FEP coating is likely to prevent from tumor ingrowth.

Scattered dose to gonads and associated risks from radiotherapy for common pediatric malignancies : a phantom study.

PURPOSE: To measure the scattered dose to ovaries and testes from radiotherapy for common pediatric malignancies and to assess the relevant risks for radiation-induced gonadal damage and hereditary disorders in future generations. MATERIAL AND METHODS: Radiotherapy for central nervous system tumors, acute leukemia, neuroblastoma, Hodgkin's disease, Wilms' tumor, and sarcoma was simulated on three humanoid phantoms representing patients of 5, 10, and 15 years of age. Ovarian and testicular dose measurements were performed using thermoluminescent dosimeters on a linear accelerator with multileaf collimator (MLC) producing 6-MV X-rays. The effect of lead block introduction into the primary beam on the gonadal dose was evaluated. Gonadal dose from radiotherapy for abdominal tumors was measured using an 18-MV photon beam. RESULTS: For a tumor dose range of 12-55 Gy, the scattered dose to ovaries was 0.5-62.4 cGy depending upon the patient's age (corresponding phantom) and treatment site. The corresponding dose to testes was 0.4-145.0 cGy. The use of blocks for field shaping can increase the gonadal dose up to a factor of 2.0 compared to that measured using MLC. Abdominal irradiation with 18-MV instead of 6-MV X-rays reduced the gonadal dose by more than 1.3 times. For female and male patients, the risk for induction of hereditary disorders was less than 81 x 10(-4) and 188 x 10(-4), respectively. CONCLUSION: The present dosimetric data suggest that pediatric radiotherapy is not associated with a risk for permanent damage to gonads excluded from the treatment volume. The risk for development of hereditary disorders in offspring conceived after exposure is low.

Energy imparted-based estimates of the effect of z overscanning on adult and pediatric patient effective doses from multi-slice computed tomography.

In the present study effective dose values normalized to computed tomography dose index measured free in air were calculated for adult, newborn, 1, 5, 10 and 15 year old patients regarding scans of the head, chest, abdomen, pelvis, abdomen and pelvis, and trunk, using the energy imparted method. The effect of z overscanning on patient doses was accounted for, and normalized doses are provided for varying beam collimation, pitch and reconstruction slice width values. The contribution of overscanning depends on patient age, anatomic region imaged, acquisition and reconstruction settings. For a head scan it constitutes 15% of the adult effective dose and 24% of the effective dose to a newborn but for an abdomen scan it may be as high as 58% for a newborn and 31% for an adult. The ratios of normalized pediatric doses relative to that for adults for helical scans depend not only on age but also on acquisition and reconstruction parameters, because of variations in the relative distance between the primary beam and the radiosensitive tissues/organs of the body. Regarding scans of the trunk, pediatric doses are up to a factor of 2.5 times higher compared to adult doses (abdominal scans), whereas for scans of the head up to a factor of 1.5. Increasing the pitch value of helical scans while maintaining the same effective mAs setting, and hence noise levels, leads to an increase in patient doses which depends on age, body region, scan and reconstruction parameters. The % difference between doses at pitch 1.5 and pitch 1 is more pronounced in the abdominal region (14% increase for adults) and in young patients (31% in a newborn and 18% in a 10 year old patient) and it is minimal in head scans (4% increase in newborns and 1% in adults). If multiple body regions are to be imaged, doses to adults can be reduced by up to 15% and 36% to children by performing single long-range scans. Scanning adult patients at 100 kVp instead of 120 kVp, results in a 32% reduction in effective dose from head scans and 38% for scans of the torso. The corresponding reduction for a 5 year old patient is 31% for the head and 37% for the trunk. Due to the combined overbeaming and overscanning effect the 24 mm collimation is more dose effective in the head mode and the 12 mm collimation in the body mode. Provided data enable informed design of examination protocols, calculation of effective dose values and familiarization with the technical features of multi-detector technology.

Influence of z overscanning on normalized effective doses calculated for pediatric patients undergoing multidetector CT examinations.

The purpose of this study was to evaluate the effect of z overscanning on normalized effective dose for pediatric patients undergoing multidetector-computed tomography (CT) examinations. Five commercially available mathematical anthropomorphic phantoms representing newborn, 1-, 5-, 10-, and 15-year-old patients and the Monte Carlo N-Particle (MCNP, version 4C2) radiation transport code were employed in the current study to simulate pediatric CT exposures. For all phantoms, axial and helical examinations at 120 kV tube voltage were simulated. Scans performed at 80 kV were also simulated. Sex-specific normalized effective doses were estimated for four standard CT examinations i.e., head-neck, chest, abdomen-pelvis, and trunk, for all pediatric phantoms. Data for both axial and helical mode acquisition were obtained. In the helical mode, z overscanning was taken into account. The validity of the Monte Carlo results was verified by comparison with dose data obtained using thermoluminescence dosimetry and a physical pediatric anthropomorphic phantom simulating a 10-year-old child. In all cases normalized effective dose values were found to increase with increasing z overscanning. The percentage differences in normalized data between axial and helical scans may reach 43%, 70%, 36%, and 26% for head-neck, chest, abdomen-pelvis, and trunk studies, respectively. Normalized data for female pediatric patients was in general higher compared to male patients for all ages, examined regions, and z overscanning values. For both male and female children, the normalized effective dose values were reduced as the age was increased. For the same typical exposure conditions, dose values decreased when lower tube voltage was used; for a 1-year-old child, for example, the effective dose was 3.8 times lower when 80 kV instead of 120 kV was used. Normalized data for the estimation of effective dose to pediatric patients undergoing standard axial and helical CT examinations on an multidetector CT system were calculated. This data was found to depend strongly on CT acquisition mode and exposure parameters as well as patient age and sex. The effective dose from a pediatric CT scan performed in axial mode was always considerably lower compared to the corresponding scan performed in helical mode, due to the additional tissue regions exposed to the primary beam in helical examinations as a result of z overscanning.

Radiation dose and risk from fluoroscopically guided percutaneous transluminal angioplasty and stenting in the abdominal region.

The objective of this study was to estimate the radiation dose and associated risks resulting from fluoroscopically guided percutaneous transluminal angioplasty with or without stent placement in the abdominal region. Average examination parameters for renal and aortoiliac procedures were derived using data from 80 consecutive procedures performed in our institute. Organ and effective doses were estimated for endovascular procedures with the use of a Monte Carlo (MC) transport code and an adult mathematical phantom. Thermoluminescent dosimeters were used in an anthropomorphic phantom to verify MC calculations. Radiation-induced risks were estimated. Results are presented as doses normalized to dose area product, so that the patient dose from any technique and X-ray unit can be easily calculated for iliac and renal PTA/stenting sessions. The average effective dose varied from 75 to 371 microSv per Gycm(2) depending on the beam quality, procedure scheme and sex of the patient. Differences up to 17% were observed between MC-calculated data and data derived from thermoluminescent dosimetry. The radiation-induced cancer risk may be considerable for younger individuals undergoing transluminal angioplasty with stent placement.

Myocardial and liver iron status using a fast T*2 quantitative MRI (T*2qMRI) technique.

This work demonstrates the use of a fast and precise methodology for evaluating myocardial and liver iron status in multitransfused thalassemic patients by means of a fast T(2) (*) quantitative MRI (T(2) (*)qMRI) technique. Myocardial and liver T(2) (*) values were calculated in 48 thalassemic patients and 21 normal subjects on a 1.5T MRI system using a breath-hold 2D single-slice multiecho gradient-echo (MEGRE) sequence (16 echoes, TR/TE1/TE16/FA = 160/2.7/37.65 ms/25 degrees ). No ECG gating was used. Myocardial T(2) (*), liver T(2) (*), and myocardial to muscle (CR/MS) and liver to muscle (LV/MS) T(2) (*) ratios were correlated with serum ferritin concentration (SFC) levels for all patients. Significant differences in myocardial and liver mean T(2) (*), CR/MS, and LV/MS T(2) (*) values between patients and normal subjects were found (P < 0.0005). Differences in paraspinous muscle mean T(2) (*) values between patients and normal subjects were not significant. Myocardial T(2) (*) and CR/MS T(2) (*) values were not correlated with SFC levels. Liver T(2) (*) and LV/MS T(2) (*) values were significantly correlated with SFC (r = 0.540, P < 0.0005). Myocardial T(2) (*) and CR/MS T(2) (*) values were not correlated with either liver T(2) (*) or LV/MS T(2) (*) values, respectively. We conclude that myocardial and liver iron deposition can be evaluated using the fast non-ECG-gated T(2) (*)qMRI technique.

Thyroid dose from common head and neck CT examinations in children: is there an excess risk for thyroid cancer induction?

This study was conducted to estimate thyroid dose and the associated risk for thyroid cancer induction from common head and neck computed tomography (CT) examinations during childhood. The Monte Carlo N-particle transport code was employed to simulate the routine CT scanning of the brain, paranasal sinuses, inner ear and neck performed on sequential and/or spiral modes. The mean thyroid dose was calculated using mathematical phantoms representing a newborn infant and children of 1year, 5 years, 10 years and 15 years old. To verify Monte Carlo results, dose measurements were carried out on physical anthropomorphic phantoms using thermoluminescent dosemeters (TLDs). The scattered dose to thyroid from head CT examinations varied from 0.6 mGy to 8.7 mGy depending upon the scanned region, the pediatric patient's age and the acquisition mode used. Primary irradiation of the thyroid gland during CT of the neck resulted in an absorbed dose range of 15.2-52.0 mGy. The mean difference between Monte Carlo calculations and TLD measurements was 11.8%. Thyroid exposure to scattered radiation from head CT scanning is associated with a low but not negligible risk of cancer induction of 4-65 per million patients. Neck CT can result in an increased risk for development of thyroid malignancies up to 390 per million patients.