Characterization of a computed tomography iterative reconstruction algorithm by image quality evaluations with an anthropomorphic phantom.

OBJECTIVE: This study aims to investigate the consequences on dose and image quality of the choices of different combinations of NI and adaptive statistical iterative reconstruction (ASIR) percentage, the image quality parameters of GE CT equipment. METHODS: An anthropomorphic phantom was used to simulate the chest and upper abdomen of a standard weight patient. Images were acquired with tube current modulation and different values of noise index, in the range 10-22 for a slice thickness of 5mm and a tube voltage of 120 kV. For each selected noise index, several image series were reconstructed using different percentages of ASIR (0, 40, 50, 60, 70, 100). Quantitative noise was assessed at different phantom locations. Computed tomography dose index (CTDI) and dose length products (DLP) were recorded. Three radiologists reviewed the images in a blinded and randomized manner and assessed the subjective image quality by comparing the image series with the one acquired with the reference protocol (noise index 14, ASIR 40%). The perceived noise, contrast, edge sharpness and overall quality were graded on a scale from -2 (much worse) to +2 (much better). RESULTS: A repeatable trend of noise reduction versus the percentage of ASIR was observed for different noise levels and phantom locations. The different combinations of noise index and percentage of ASIR to obtain a desired dose reduction were assessed. The subjective image quality evaluation evidenced a possible dose reduction between 24 and 40% as a consequence of an increment of ASIR percentage to 50 or 70%, respectively. CONCLUSION: These results highlighted that the same patient dose reduction can be obtained with several combinations of noise index and percentages of ASIR, providing a model with which to choose these acquisition parameters in future optimization studies, with the aim of reducing patient dose by maintaining image quality in diagnostic levels.

Diffusion-Weighted Magnetic Resonance Imaging and ADC Maps in the Diagnosis of Intracranial Cystic or Necrotic Lesions. A Retrospective Study on 49 Patients.

This study evaluated the usefulness of diffusion-weighted (DW) magnetic resonance imaging (MRI) and ADC maps in the differential diagnosis of brain abscesses from cystic or necrotic neoplasms. MR images of 49 patients with 54 lesions were examined retrospectively. All patients underwent conventional MRI and DWI, and ADC values were calculated by placing ROIs of 30 mm(2) manually over the cystic part of the lesions. On DWI, all cystic portions of abscesses were hyperintense. Mean ADC values were 0.48×10 mm(2)/s (range 0.41-0.54×10 mm/s) for pyogenic abscesses, 0.73×10 mm(2)/s (range 0.65-0.91×10 mm/s) for mycotic abscesses and 0.6 mm(2)/s for Nocardia abscess. Cystic areas appeared hypointense on DWI in 33/44 tumours (mean value ADC 1.96 mm(2)/s). Eleven tumours (11/44) appeared hyperintense on DWI: eight metastases from lung cancer (mean ADC value 0.86 mm(2)/s, range 0.75-1.2 mm(2)/s), two GBMs (mean 0.7 mm(2)/s, range 0.67-0.76 mm(2)/s) and one anaplastic astrocytoma (ADC value 1.24 mm(2)/s). ADC values may help in differentiating pyogenic abscess from brain tumors or metastatic lesions.

Automated quality control in computed radiography.

PURPOSE: The purpose of this paper is to describe the automation of quality control procedures on photo-stimulable imaging plates by means of an image-processing tool providing automatic reading of the images and automatic calculation of the quality parameters monitored. MATERIALS AND METHODS: Quality-control procedures were performed according to the main available guidelines. The quality assurance programme was applied to several Kodak and Philips devices in four radiological departments. The automatic image-processing tool was developed using public domain software (Java-based ImageJ software) and contains both reading and computation procedures. RESULTS: The quality checks and algorithms described were successfully applied, proving useful for identification of defective plates and for implementation of the quality assurance programme. The use of automation allowed significant savings in the time required for quality checks. CONCLUSIONS: Completely automated image reading allows substantial economic and human resources savings, as it eliminates much of the transfer, reproduction, processing and filing procedures.

Reversible encephalopathy syndrome: report of 12 cases with follow-up.

We report the clinical and neuroradiological features of reversible encephalopathy syndrome and follow-up results in 12 patients. This syndrome seems to be the result of an acute encephalopathy showing with brain edema mainly in the white matter (vasogenic edema). Diffusion-weighted magnetic resonance images are useful to distinguish this entity from acute ischemia. Early recognition and treatment often lead to complete neurological recovery. If unrecognized, the patient's condition can progress to central nervous system failure.

Evidence-based medicine and radiology: how to build a guideline. An attempt in minor head injury.

PURPOSE: To evaluate the use of Evidence-based Medicine (EBM) to build radiological Guidelines, with the aim to have a better compliance by users. It has been decided to work on minor head injury, where we have found, in our institution, a wide and unjustified use of conventional skull x-ray. MATERIAL AND METHODS: A Workgroup, that reunites the main figures that enter in the management of the patient with minor head injury, has been created within our Hospital. The bibliography relative to the problem has been selected, employing criteria that held account of the methodological correctness, and in particular the existing Guidelines have been carefully analysed. It is therefore proceeded drawing up a Guideline that adhered to the principles of the EBM, adapting it to the hospital environment. Subsequently it has been passed to the phase of its implementation, with reunions in small groups of the involved professional figures, the distribution of informative material and the use of poster that reassumed the diagnostic flow-chart. Moreover a survey of the relative data to the number of skull x-ray and brain TC, executed in the patients with head trauma, has been completed. RESULTS: The analysis of the data relative to the variation of the number of demands for skull Rx after introduction of the Guideline has demonstrated a great reduction (-83,8%), with little variation of the number of brain TC (+17,0%); such reduction has naturally implicated an important reduction of costs (-25,2%) and of the x-ray dose to population, measured to the crystalline (34,5%) and to thyroid (-71,0%). CONCLUSIONS: The employ of the EBM in the Guideline creation, beyond representing the more correct methodology, concurs to obtain a greater adhesion from the users involved in management of the patient; in particular this happens if the Guideline is a product of a vast contribution and if it is supported from all additional procedures that can be useful for its implementation.

[Check of compliance with quality criteria for diagnostic radiographic images in quality control]. / Verifica del rispetto dei livelli diagnostici di riferimento nella radiodiagnostica nell'ambito dei controlli programmati della qualità.

PURPOSE: To devise and implement a programme of measurements to assess the entrance surface dose for a standard-sized patient and to check the compliance with diagnostic reference levels. MATERIAL AND METHODS: Dose evaluation was performed on 40 radiographic instruments. The exposure parameters were collected for the main radiographic procedures (chest, skull, spine, pelvis, abdomen) each performed with instrument on a standard-sized patient. The output of each X-ray tube at 70, 80, 90, 100, 110 and 120 kV was measured with a solid state detector during quality controls. Beam quality and geometric characteristics of the equipment were also determined. The entrance surface dose for a standard patient was assessed for each procedure carried out with the 40 instruments, thus obtaining a total of 155 radiographic techniques. Finally, the method was validated by comparing the values obtained with the solid state and an ionization chamber for X-ray beam detector. RESULTS: The comparison between the solid state detector and the ionisation chamber demonstrated a good agreement. Results show that reference diagnostic levels are respected in most examinations (147/155) even if exposure values do not always comply with those indicated by European guidelines. The measurement programme seems to be applicable in hospital practice where the large number of radiographics instruments and procedures requires the acquisition and processing of a large number of data. CONCLUSIONS: The evaluation of patient dose during quality control is feasible and allows a first check of compliance with reference levels in order to identify which procedures can be optimised by means of more specific measurements and assessments.

Image-aided estimate of tumor burden in Hodgkin's disease: evidence of its primary prognostic importance.

PURPOSE: To explore a more direct method for evaluating tumor burden (TB) in Hodgkin's disease (HD) and to verify its prognostic importance. PATIENTS AND METHODS: The volume of TB at diagnosis was directly and retrospectively measured in 121 HD patients through images of the lesions recorded by computed tomographic (CT) scan of the thorax, abdomen, and pelvis for all deep sites of involvement and many superficial ones, and by ultrasonography (US) for the remaining superficial lesions. RESULTS: The TB, which was obtained from the sum of the volumes of all the lesions measured on CT scans and US and normalized to body-surface area (relative TB [rTB]), showed a median value of 102.6 cm(3)/m(2) (range, 2.2 to 582.8). At multivariate analysis for prognostic value, rTB was the parameter that statistically correlated best with time to treatment failure (P = 2.2 x 10(-6)), followed by erythrocyte sedimentation rate (ESR) (P =.0003), and serum fibrinogen (P =.0112). The prognostic discrimination allowed by rTB alone proved to be clearly superior to that obtained with the score of the International Prognostic Factor Project. The rTB was found to be correlated with many clinical staging parameters (bulky disease, number of involved lymph node regions, serum lactate dehydrogenase, ESR, hemoglobin, Karnofsky index), but its predictability from these variables was low (R(2) =.668). CONCLUSION: Relative TB is emerging as a strong prognostic factor in HD, more powerful than and largely independent of those hitherto known and used. Further studies are needed to confirm these results and exploit their clinical value, particularly the relationship among rTB, drug doses, and response.

Brain manganese deposition and blood levels in patients undergoing home parenteral nutrition.

BACKGROUND: Extrapyramidal syndrome and alterations in brain magnetic resonance images are described in patients undergoing long-term home parenteral nutrition (HPN) and in cholestatic patients. These abnormalities have been correlated to basal ganglia manganese (Mn) accumulation. METHODS: A longitudinal 1-year study was conducted on 15 patients undergoing HPN (median duration, 3.8 years; range, 1.7-10; median Mn parenteral supplementation, 0.1 mg/d). Whole-blood, plasma, intra-erythrocytes, and urinary Mn concentrations were measured and brain magnetic resonance was performed at the beginning (time 0) and after 1 year of Mn intravenous supplementation withdrawal (time 1). No patients showed psychosis, extrapyramidal syndrome, or cholestasis. RESULTS: At time zero, 10 of 15 patients (67%) showed paramagnetic accumulation on cerebral magnetic resonance images; at time 1 there was a reduction of cerebral Mn accumulation. In all patients, blood-Mn levels were significantly reduced after 1 year of Mn intravenous supplementation withdrawal. CONCLUSIONS: Patients receiving long-term HPN showed an elevated incidence of alterations in brain magnetic resonance images with a median Mn intravenous supplementation of 0.1 mg/d. Mn supplementation withdrawal significantly decreased metal levels in blood and brain storage. We noticed that the intra-erythrocyte Mn level was a good index of Mn status.

MRI diagnosis of intramedullary metastases from extra-CNS tumors.

The purpose of this study was to evaluate the topography, morphology and contrast enhancement of the intramedullary metastases (IM) from extra-CNS neoplasms. We report the results of a multicenter retrospective study on 18 patients with 26 IM examined with a 0.5T MR imaging system; intravenous injection of Gd-DTPA was performed in all cases. We found that the lesions are most frequently single, oval shaped, and small, with little or no deformation of the spinal cord (14 of 26 IM). They appear isointense on spin-echo T1-weighted images (24 of 26 IM), with a homogeneous and generally nodular high contrast enhancement after Gd-DTPA injection (21 of 26 IM), and present on T2- and proton-density-weighted sequences with a pronounced perilesional, pencil-shaped hyperintensity of the surrounding cord which is more evident in the cranial part of the cord referring to the IM.

Usefulness of motor evoked potentials in compressive myelopathy.

Motor Evoked Potentials elicited by transcranial magnetic stimulation were recorded from 1 degree Dorsal Interosseus for the upper limbs and from Extensor Digitorum Brevis for the lower limbs in 42 subjects with compressive myelopathy (36 in the cervical region and 6 in the dorsal region), radiologically defined by Nuclear Magnetic Resonance (NMR) imaging, with no clinical and radiological signs of radiculopathy. Central motor conduction abnormalities in the cortex-C8 and cortex-L5 tract were compared with clinical signs of motor impairment and with NMR findings. The subjects with medullar hyperintensity of NMR signal at the compression site level, showed a central conduction time (C.C.T.) prolongation in at least one side in the 70% of cases in the cortex-C8 tract and in the 95% of cases in the cortex-L5 tract, while in the cases with no compression site alterations of signal, C.C.T. abnormalities were observed only in 25% in the cortex-C8 tract and in 42% in the cortex-L5 tract. In 12 subjects (10 with cervical compression and 2 with dorsal compression) we compared Motor Evoked Potentials before, two weeks and two months after surgical decompression. The C.C.T. cortex-C8 and cortex-L5 improved at least in one side in 11 out of the 12 subjects, showing a good correlation with clinical recovery. In the examined patients we found a latency reduction statistically significant between the first and second investigation, with a trend to stabilization in the following controls.

[A new catheter for enteroclysis: Torino 1. Results in 398 cases]. / Nuovo set per enteroclisi: Torino 1. Risultati in 398 casi.

The authors report on the use a new barium enema catheter employed in 398 patients from January, 1990 through June, 1991. Its innovative characteristics and several possible uses are compared with those of conventional equipment. Particularly, the advantages offered by the various possible placement sites of the catheter--i.e., the II duodenal portion and beyond the ligament of Treitx--are discussed, together with its different uses according to clinical symptoms: its best location is beyond the ligament of Treitz in subocclusions, versus in the II duodenal portion if tumors or other duodenal conditions are suspected. The new catheter exhibited 100% accuracy; the average exposure time for radioscopy during its positioning was 3 minutes. A selected group of 149 patients was examined for complications, which were few (8%), of poor importance, short and completely curable.

Evaluation of bone marrow cellularity by magnetic resonance imaging in patients with myelodysplastic syndrome.

Magnetic resonance imaging (MRI) is a safe modality for examining the bone marrow and it is quite effective in revealing marrow involvement in hematological malignancies. MRI has been compared with needle marrow biopsy in 22 patients with myelodysplastic disorders. A fairly good concordance has been demonstrated in 79% of cases. However, in 5 patients MRI revealed that bone marrow hyperplasia was not generalized. Therefore in elderly patients with MDS, MRI of the spine allows the quantification of bone marrow hyperplasia with a greater accuracy than bone marrow biopsy and this may be useful for monitoring the effect of cytostatic treatment.

[Magnetic resonance in the study of residual mediastinal masses after therapy of lymphoma]. / La risonanza magnetica nello studio delle masse mediastiniche residue dopo terapia nei linfomi.

Forty-five patients with mediastinal spread of malignant, Hodgkin's and non-Hodgkin's lymphomas were examined with MR Imaging at 0.5 T. Ninety-two examinations were performed at diagnosis and/or during and after treatment to investigate MR capabilities in distinguishing fibrous tissue from active disease in the masses residuing after therapy--which cannot be done by means of CT. MR results indicated T2-weighted sequences to be the most useful. MR results were compared with the data collected from follow-up, clinics, and biology. MR Imaging had high accuracy (92.1%). The number of false negatives was very low, thanks to the low intensity of fibrous tissue, while a relatively high number of false positives was observed, probably due to the difficulties in discriminating inflammatory from neoplastic tissue.

Role of thoracic computed tomography in the treatment plan of Hodgkin's disease.

Conventional chest X-rays and CT scans, performed at the time of the initial staging in 67 patients affected by Hodgkin's disease, were reviewed and compared. CT scans provided evidence of disease not shown by concomitant conventional chest X-rays in 10 patients (15%). The impact on patient management of the additional CT data was evident in 8 cases (11.9%), either changing the whole treatment plan (4 patients) or enlarging radiation ports (4 patients). Traditional prognostic features did not influence the outcome, and only hilar adenopathy adversely affected event-free survival, without however reaching statistical relevance (p greater than 0.05). Our data suggest that thoracic CT scan is helpful in drawing up the treatment plan, while its role in identifying new prognostic factors is still uncertain.