Multislice CT: technical principles and clinical applications.

The aim of this article is to describe the main technical differences between multi-slice Computed Tomography (CT) and spiral CT. We also briefly discuss the diagnostic benefits of this new technology which consolidates and expands on the results achieved with spiral CT in the 90s. More specifically, gantry speed and improved spatial resolution in the z axis considerably expand angiographic and cardiac applications, allow high-quality multiplanar and 3D reconstructions, and introduce CT in organ perfusion studies (particularly those of heart and brain).

Cost analysis of different protocols for imaging a patient with acute flank pain.

The aim of this study was to analyse the costs of different diagnostic approaches to patients with acute flank pain. Four different diagnostic approaches were considered: (a) spiral CT without contrast medium (CM); (b) plain film, ultrasonography (US) and intravenous urography (IVU)--the latter procedure is used in our department in cases still unsolved following the former investigations (28% in our experience); (c) plain film, US and spiral CT without CM (as an alternative to IVU in 28% of cases); and (d) IVU. The cost of each procedure in a university hospital was calculated, following analysis of the differential costs of each investigation (equipment, depreciation and maintenance costs, related materials and services, radiologists, radiographers, nurses) and their common costs (auxiliary personnel and indirect internal costs). Finally, we calculated the full cost of each procedure and applied it to the different diagnostic approaches. The full cost of each approach was: (a) spiral CT without CM = 74 Euro; (b) plain film, US and IVU (28%) = 66.89 Euro; (c) plain film, US and spiral CT without CM (28%) = 64.93 Euro; (d) IVU = 80.90 Euro. Intravenous urography alone or in unsolved cases is not to be considered because it provides higher costs and worse diagnostic results, whereas X-ray dose to patient is almost equal between IVU and spiral CT. Spiral CT integrated to plain film and US in unsolved cases could be preferred because of lower cost and dose to patient, though reaching a diagnostic conclusion may take longer than an immediate spiral CT.

Relationships between radiologists and clinicians: results from three surveys.

AIM: To analyse reasons for and the nature of clinico-radiological contacts and their clinical impact. MATERIALS AND METHODS: Three different surveys were performed. (1) Data concerning contacts between staff radiologists (n = 20) and clinicians during 10 consecutive working days were collected; (2) staff clinicians (n = 174) filled in a questionnaire asking for their opinions about relationships with radiologists; (3) staff radiologists collected data about contacts with clinicians related to more urgent/complicated cases. Radiologists assessed the clinical impact of the radiological procedure and of the consultation. RESULTS: (1) During 220 working days 20 radiologists had a mean of 3.95 contacts per day (48.2% personal contacts, 51.8% telephone contacts), amounting to a personal total of 21.65 min per day. These contacts amounted to a total of 7.08 h per day, roughly one whole-time equivalent radiologist. (2) These consultations helped to refine the diagnostic strategy often (12.6%) or sometimes (71.4%) and to alter therapeutic decisions often (10.4%) or sometimes (56.6%). (3) The initial clinical diagnosis was changed in 50% of cases and the therapy was substantially changed on the basis of further radiological investigations and clinical-radiological discussion in 60% of cases. CONCLUSION: Clinical-radiological consultations are time consuming but have a beneficial diagnostic and therapeutic impact.

Dynamic magnetic resonance imaging in the assessment of chronic medical nephropathies with impaired renal function.

We examined the value of dynamic magnetic resonance imaging (MRI) in chronic renal disease with renal insufficiency. In 33 consecutive patients (21 vascular nephropathy, 12 glomerular nephropathy) MRI was performed using a 1.5-T unit and a body coil, with SE T1-weighted (TR/TE = 600/19 ms) and dynamic TFFE T1-weighted sequences (TR/TE = 12/5 ms, flip angle = 25 degrees ) after manual bolus injection (via a cubital vein) of 0.1 mmol/kg Gd-DTPA-BMA. Morphological evaluation was performed in unblinded fashion by three radiologists, evaluating renal size, cortical thickness, and corticomedullary differentiation. Functional analysis was performed by one reviewer. Time-signal intensity curves, peak intensity value (P), time to peak intensity (T), and the P/T ratio were obtained at the cortex, medulla, and pyelocaliceal system of each kidney. The relationship of these parameters to serum creatinine and with creatinine clearance was investigated. A good correlation between morphological features of the kidneys and serum creatinine values was found. Morphological findings could not distinguish between vascular and glomerular nephropathies. A statistically significant correlation (P <0.01) between cortical P, cortical P/T, medullary P, and serum creatinine and creatinine clearance was found. A significant correlation (P <0.01) was also found between cortical T, medullary P/T, T of the excretory system, and creatinine clearance. The cortical T value was significantly higher (P <0.01) in vascular nephropathy than in glomerular nephropathy. Thus in patients with chronic renal failure dynamic MRI shows both morphological and functional changes. Morphological changes are correlated with the degree of renal insufficiency and not with the type of nephropathy; the functional changes seem to differ in vascular from glomerular nephropathies.

Functional MR with use of FLASH sequences in the evaluation of the phono-articulatory tract.

The aims of this study are to determine visualization of normal phonation structures with the use of MR fast sequences and anatomical reference indices which can be used in evaluating upper resonator pathologies. A total of 12 normal subjects were studied, a 1 T system, a volumetric receiving head and neck coil and FLASH sequences for one sagittal and two coronal scans. Each subject was instructed to take a deep breath and then to produce the vowel sounds for the entire duration of the scan. The movement of the following anatomical structures were considered: lips, tongue, soft palate, pharynx and epiglottis. For each subject sagittal scans were used to measure the minimal palate tongue distance (p-t), the minimal anterio-posterior diameter of the mesopharynx (mp), and the epiglottis excursion angle (ep) with respect to the plane determined by the false vocal cords. Our results were compared with a diagrammed representation of tongue movements (vocal trapezium). This study underlines the validity of MR imaging techniques in the study of the phono-articulatory tract, because MR provided good detail of the phono-articulatory structures enabling an overall functional evaluation. MR would appear useful in evaluating defects in the velum and palate, in staging of oropharyngeal neoplasms and in surgical reconstructions of the tongue.

[Colonoscopy with computed tomography with volume reconstruction. The results and a comparison with endoscopy and surgery]. / Colonscopia con Tomografia Computerizzata con ricostruzioni di volume. Risultati e confronto con endoscopia e chirurgia.

PURPOSE: Virtual CT colonoscopy is a novel technique whose diagnostic accuracy and clinical yield are currently investigated. Several studies have shown its capabilities in detecting colon and rectal cancers. We report the results of a preliminary experience with the volume rendering technique and compare CT colonoscopy with endoscopy and surgery. MATERIAL AND METHODS: Our series consisted of 25 patients with colon cancer confirmed at endoscopy and/or surgery. All examinations were carried out with a spiral CT scanner Philips Tomoscan AVE1. Intestinal preparation was adequate in all patients, consisting in gas insufflated immediately before acquisition, after the injection of 100 mL iodinated contrast agent. All examination were performed in prone position using axial 5 mm slices with 5 mm table feed (pitch 1) and 2 mm reconstruction index; 120 kV and 200-250 mA were used. Images were transferred to a workstation (Easy Vision, Philips, release 4.2.1.1) for processing. We acquired multiplanar (MPR) and virtual endoscopic images with volume rendering; the selected threshold was -250 to -600 Hounsfield Units. Virtual endoscopic images could be obtained in 23 of 25 cases. The results of the radiological study were compared with endoscopic and surgical findings in 25 and 17 cases, respectively. RESULTS: Endoscopy and surgery detected 46 lesions: 29 were malignant and 17 benign. Axial CT and MPR alone detected 35 lesions (76%), 29 of them malignant and 6 benign. The 11 benign lesions missed by axial CT ranged 6-8 mm in diameter. There were no false positives. CT colonoscopy alone detected 66 lesions, but 22 of them were false positive due to residual stool in the colon (21 cases) and to residual barium in the colon (1 case). Combining CT colonoscopy and axial and MPR images enabled to correct the false positive diagnoses made by CT colonoscopy alone and to decrease the false negative ratio of axial and MPR images. Forty-one of 44 lesions (93%) were detected. Thirty-seven lesions were found in the 17 surgical patients; 34 of them were correctly identified combining CT colonoscopy and axial and MPR findings, while endoscopy detected only 31 lesions. Thus, CT had 92% sensitivity, versus 83% of fiberoptic endoscopy. CONCLUSION: In this preliminary experience volume rendering CT colonoscopy exhibited high sensitivity in detecting colon cancers, but their correct evaluation and characterization can be obtained if axial and MPR studies are combined. Further investigation and technological developments are necessary to define the yield of this new technique.

Retroperitoneal nodular fasciitis: magnetic resonance imaging (MRI) and pathological features.

A case of pelvic nodular fasciitis, with particular reference to its peculiar radiological and pathological features is described. Only a few cases of pelvic nodular fasciitis are reported in the English literature and at the best of our knowledge, this is the first case of retroperitoneal origin. This report discusses the role of MRI in the characterization of soft tissue masses. No specific MRI findings of nodular fasciitis were identified and MRI doesn't add any contribution to the differential diagnosis between benign and malignant lesions. As a consequence, the histopathological examination is necessary for a definitive diagnosis.

[Magnetic resonance with fat-saturation sequences in studying the upper abdomen: the normal semeiological aspects]. / Risonanza Magnetica con sequenze con saturazione del grasso nello studio dell' addome superiore: aspetti semeiologici normali.

The fat-saturation (FAT-SAT) MR technique decreases the signal intensity of fat in tissues, though yielding the T1, T2 and proton-density (PD) information available on spin-echo (SE) sequences. To investigate the potentials of FAT-SAT sequences in MRI of the upper abdomen, the authors carried out a prospective study including 129 subjects, namely 12 normal volunteers and 117 patients with different abdominal conditions. The patients were submitted to T1-weighted SE sequences (TR 500-600 ms, TE 15 ms), T2W SE (TR 1600-1730 ms, TE 80 ms) and PD SE (TR 1600-1730 ms, TE 20 ms). The images obtained with and without fat suppression were compared both qualitatively and quantitatively, with a special emphasis on the normal anatomy of the upper abdomen: we investigated the efficacy of subcutaneous and retroperitoneal fat suppression (116/129 cases, 90%), the reduction in respiratory and chemical shift artifacts (112/129 cases, 87%) and the better visualization of parenchyma (119/129 cases, 93%) and of other abdominal structures. Concerning the quantitative study, we calculated the signal-to-noise ratio (S/N) for liver, spleen, pancreas, adrenal glands, renal cortex and medulla, the improvement of contrast in these organs after retroperitoneal fat suppression (conspicuity) and the increase in contrast between organs (dynamic range). The statistical analysis showed significant differences between the sequences with and those without fat suppression. Correlations were found between observers' and quantitative evaluations, suggesting that the better yield of FAT-SAT sequences is probably due to three factors: 1) retroperitoneal and subcutaneous fat suppression; 2) increase in S/N ratio for pancreas and renal cortex on T1W images; 3) reduction in the dynamic range of signal intensity, which increases contrast between pancreas, adrenal glands and renal cortex relative to adjacent structures, especially on T2W or PD sequences. The results of this study suggest that FAT-SAT sequences are useful because fat suppression increases contrast and improves image quality, reducing respiratory and chemical shift artifacts.