Radiofrequency ablation for benign thyroid nodules.

Benign thyroid nodules are an extremely common occurrence. Radiofrequency ablation (RFA) is gaining ground as an effective technique for their treatment, in case they become symptomatic. Here we review what are the current indications to RFA, its outcomes in terms of efficacy, tolerability, and cost, and also how it compares to the other conventional and experimental treatment modalities for benign thyroid nodules. Moreover, we will also address the issue of treating with this technique patients with cardiac pacemakers (PM) or implantable cardioverter-defibrillators (ICD), as it is a rather frequent occurrence that has never been addressed in detail in the literature.

The role of CEUS in the characterization of hepatocellular nodules detected during the US surveillance program--current practices in Europe.

The basic pathological feature for the differential diagnosis between hepatocellular carcinoma (HCC) and non-malignant hepatocellular nodules in cirrhotic patients detected during ultrasound (US) is the vascular supply to the nodule. Computed tomography (CT) and magnetic resonance imaging (MRI) are considered reference imaging techniques for depicting hepatocellular nodule vascularity in the noninvasive diagnosis of HCC. Contrast-enhanced US (CEUS) improves the diagnostic performance of unenhanced US in the diagnosis of HCC, giving an overall diagnostic accuracy that is similar to that of CT, even for nodules smaller than 2 cm. An additional diagnostic feature of CEUS relative to CT is the possibility to visualize contrast wash-in to hepatic nodules during the arterial phase and contrast washout during the portal venous and late phases. Sensitivity for the diagnosis of HCC with combined assessment of CEUS and CT is higher than for separate assessments of CEUS and CT due to the reduction of false-negative findings. CEUS represents a competitive imaging method from an economic point of view, and is an effective imaging tool for assessing the therapeutic outcome after surgery, ablation therapy, and transarterial chemoembolization (TACE).

64-Slice CT urography: optimisation of radiation dose.

PURPOSE: This study assessed means by which to optimise 64-slice computed tomography urography (CTU) in evaluating the urinary tract, with a view to obtaining the best trade-off between image quality and radiation dose. MATERIALS AND METHODS: Image quality was analysed in terms of spatial and contrast resolution on several scans of a phantom performed with automatic dose modulation and different reconstruction kernels and accepted noise level. Data were compared with the radiation dose values recorded for 52 patients who underwent CTU examination. RESULTS: Radiation dose and image quality differed considerably depending on the reconstruction parameters, even though a higher dose did not always imply better image definition. Data obtained in the phantom were consistent with those obtained in patients. Depending on the clinical problem, the radiation dose varied from 6.2 to 17.6 mSv. CONCLUSIONS: CTU cannot be considered a standard examination: the scan parameters need to be adapted to the image quality required for the specific clinical problem.

64-Slice CT urography: 30 months of clinical experience.

PURPOSE: This study sought to assess the diagnostic accuracy of 64-slice computed tomography urography (CTU) in evaluation of the urinary tract. MATERIALS AND METHODS: A total of 322 CTU procedures were carried out in 317 consecutive patients (mean age 64.4 years). The findings were compared with previous and subsequent patient workup considering both laboratory and imaging studies, such as urine cytology, abdominal ultrasound and CT, cystoscopy, retrograde pyelography, surgery and pathology. RESULTS: Out of 322 CTU examinations, 169 showed significant urinary tract changes, whereas 153 revealed no urinary disease, in good agreement with the follow-up. In particular, in bladder evaluation, for which we have a direct comparison with cystoscopy in 125 patients, we calculated a CTU sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of 85%, 94%, 92%, 89% and 90%, respectively. CONCLUSIONS: CTU was accurate for urinary tract evaluation, but it cannot replace cystoscopy in patients in whom a malignant bladder disease is suspected.

Clinical application of low-dose phase contrast breast CT: methods for the optimization of the reconstruction workflow.

Results are presented of a feasibility study of three-dimensional X-ray tomographic mammography utilising in-line phase contrast. Experiments were performed at SYRMEP beamline of Elettra synchrotron. A specially designed plastic phantom and a mastectomy sample containing a malignant lesion were used to study the reconstructed image quality as a function of different image processing operations. Detailed evaluation and optimization of image reconstruction workflows have been carried out using combinations of several advanced computed tomography algorithms with different pre-processing and post-processing steps. Special attention was paid to the effect of phase retrieval on the diagnostic value of the reconstructed images. A number of objective image quality indices have been applied for quantitative evaluation of the results, and these were compared with subjective assessments of the same images by three experienced radiologists and one pathologist. The outcomes of this study provide practical guidelines for the optimization of image processing workflows in synchrotron-based phase-contrast mammo-tomography.

Regional and systemic haemodynamic response to aortography in hypertensives.

OBJECTIVE: To study the effects of aortography and of aortic counterflow bolus injection per se on regional and systemic haemodynamics in hypertensives in comparison to normotensive matched controls. DESIGN AND METHODS: Mean blood velocity (MBV) and pulsatility index (PI)--as an index of regional vascular resistance--by the Doppler technique, at the femoral, common carotid and brachial arteries, finger arterial pressure and electrocardiographic R-R' interval were monitored beat-by-beat, before, during and for 3 min following counterflow bolus injections into the abdominal aorta of 40 ml/2.6 s of iopamidol (I), iso-osmolar mannitol (M) and 0.9 N saline (S), in 11 hypertensive and nine normotensive patients. RESULTS: After bolus injection of iopamidol, MBV increased to a peak at 35+/-5 s, both in normotensive (deltaMBV versus baseline +16.7+/-9.9 cm/s; P < 0.01) and in hypertensive subjects (deltaMBV versus baseline: +13.9+/-6.6 cm/s; P < 0.01). At the same time, the PI decreased both in normotensive (deltaPI versus baseline: -4.05+/-2.49; P < 0.01) and in hypertensive subjects (deltaPI versus baseline: -3.02+/-2.25; P < 0.01). After M boluses, the haemodynamic changes were of the same direction and magnitude as I for both groups, while after S the magnitude was approximately 50% lower. No significant differences were observed between normotensive and hypertensive subjects. In other vascular circulations, a 15% increase of the early diastolic backflow in the brachial artery, in phase with the femoral artery haemodynamic changes, was the only evidence of the procedure. Mean arterial pressure decreased and heart rate increased in phase with flow changes of the femoral artery. CONCLUSIONS: (1) The regional flow and systemic pressure changes observed during aortography seem, at least partially, to be due to the hydrodynamic perturbation induced by bolus injection per se. (2) The physical and chemical properties of the contrast media and therefore the probable different shear-stress modifications induced by the fluid injected could explain why the haemodynamic changes were greater after I compared to S and were more similar to M. (3) Hypertensive subjects did not show a different vasoreactive response in comparison to normotensive subjects during aortography.

Comparison between the efficacy of dimeric and monomeric non-ionic contrast media (iodixanol vs iopromide) in urography in patients with mild to moderate renal insufficiency.

Non-ionic dimers induce less diuresis than non-ionic monomers, resulting in increased opacification of the urinary tract in intravenous (i.v.) urography. This double blind, comparative, randomized, parallel trial compared the efficacy of iodixanol (non-ionic dimer) and iopromide (non-ionic monomer) in 100 patients with mild to moderate renal insufficiency (serum creatinine of 135 to 265 mumol l-1) who underwent i.v. urography. A total dose of 600 mgI kg-1 bw of iodixanol (320 mgI ml-1) or iopromide (300 mgI ml-1) was injected. Radiographs were blindly evaluated by three radiologists who analysed different parameters (renal border visualization, nephrogram density, calyceal filling and density, papillary blush detection, delineation of collecting ducts, renal pelvis opacification, visualization of ureters, bladder density, bladder distention). Densitometric evaluation on the renal pelvis and bladder was also performed. Iodixanol showed better filling and density of the calyces (p = 0.004), more frequent detection of papillary blush (p = 0.003) and better opacification of the renal pelvis (p = 0.006). No significant differences between the two contrast media were found in regard to other parameters. In conclusion, the results confirmed theoretical expectations. The non-ionic dimer iodixanol is to be preferred to a non-ionic monomer such as iopromide in i.v. urography on patients with impaired renal function.

Diffusion-weighted MRI in the evaluation of renal lesions: preliminary results.

The purpose of this study was to evaluate the capability and the reliability of diffusion-weighted MRI in the evaluation of normal kidney and different renal lesions. 39 patients (10 normal volunteers and 29 patients with known renal lesions) underwent MRI of the kidneys by using a 1.5 T superconducting magnet. Axial fat suppressed turbo spin echo (TSE) T(2) and coronal fast field echo (FFE) T(1) or TSE T(1) weighted images were acquired for each patient. Diffusion-weighted (DW) images were obtained in the axial plane during breath-hold (17 s) with a spin-echo echo planar imaging (SE EPI) single shot sequence (repetition time (TR)=2883 ms, echo time (TE)=61 ms, flip angle=90 degrees ), with b value of 500 s mm(-2). 16 slices were produced with slice thickness of 7 mm and interslice gap of 1 mm. An apparent diffusion coefficient (ADC) map was obtained at each slice position. The ADC was measured in an approximately 1 cm region of interest (ROI) within the normal renal parenchyma, the detected renal lesions and the collecting system if dilated. ADC values in normal renal parenchyma ranged from 1.72 x 10(-3) mm(2) s(-1) to 2.65 x 10(-3) mm(2) s(-1), while ADC values in simple cysts (n=13) were higher (2.87 x 10(-3) mm(2) s(-1) to 4.00 x 10(-3) mm(2) s(-1)). In hydronephrotic kidneys (n=6) the ADC values of renal pelvis ranged from 3.39 x 10(-3) mm(2) s(-1) to 4.00 x 10(-3) mm(2) s(-1). In cases of pyonephrosis (n=3) ADC values of the renal pelvis were found to be lower than those of renal pelvis of hydronephrotic kidneys (0.77 x 10(-3) mm(2) s(-1) to 1.07 x 10(-3) mm(2) s(-1)). Solid benign and malignant renal tumours (n=7) showed ADC values ranging between 1.28 x 10(-3) mm(2) s(-1) and 1.83 x 10(-3) mm(2) s(-1). In conclusion diffusion-weighted MR imaging of the kidney seems to be a reliable way to differentiate normal renal parenchyma and different renal diseases. Clinical experience with this method is still preliminary and further studies are required.

Systemic and regional haemodynamic effects of aortofemoral angiography.

UNLABELLED: The aim was to investigate the regional and systemic haemodynamic consequences of bolus injection of fluids with different physical properties in the course of routine aortography. Iopamidol was compared with an equiosmolar solution of mannitol and with a 0.9 N saline solution. Continuous blood flow and Pulsatility Index (PI), as an index of regional vascular resistance, were measured by Doppler technique. Finger arterial pressure and heart rate were monitored at the time and for 3 min following each intraaortic bolus injections. The patients who underwent routine aortography were grouped according to the site of the flow measurements: common femoral artery, common carotid artery and brachial artery. Flow changes induced by the bolus infusion were evident for all the fluids but only at the femoral artery level. After an immediate (3 +/- 2 s) and brief (2 +/- 2 s) but marked reduction of flow and in-phase increase of PI following the bolus, further haemodynamic changes were observed only in the femoral artery, with a peak at 35 +/- 10 s and returning to baseline values after 70 +/- 15 s, in terms of both increased mean blood velocity and decreased PI. Saline and mannitol induced overall blood velocity alterations of 54% and 80%, respectively, and PI reductions of 44% and 57% compared with those induced by iopamidol. In the other vascular areas there was only a 17 +/- 2% increase of the physiological early diastolic backflow at the brachial artery level. Blood pressure decreased and heart rate increased in phase with the flow changes of the femoral artery. IN CONCLUSION: (1) a dramatic rheodynamic perturbation at the site of injection induces a vasodilating stimulus; (2) the haemodynamic response following injection results in marked vasodilation of only the tributary vascular bed; (3) flow steal may occur from other beds towards the lower limb vascular beds owing to vascular impedance imbalance; (4) a reduction of systemic arterial pressure is induced in phase with the regional vascular events and a reflex increase of the heart rate; and (5) the physical properties of the injected fluids influence the intensity of the perturbation, although the decisive triggering factor is the counterflowing bolus per se.

Ultrasonography and PACS.

Expectations and problems related to picture archiving and communication systems handling of ultrasound images are discussed. Sonography has peculiarities that must be considered when its integration with picture archiving and communication systems is planned, namely: (1) data volume is about 3 Mb per ultrasound examination and is usually lower than that of other imaging modalities; this makes many requirements less strict; (2) color images represent further problems which can however be solved with systems capable of performing the analog-to-digital conversion in more than 8 bits; (3) the available equipment comes with/without digital ports; the interfaces between the ultrasound unit picture archiving and communication systems are usually based on frame grabbing which might be sufficient for sonography; (4) equipment may be located in different departments or in private offices. Therefore solutions (mini-PACS limited to ultrasound, sub-PACS with a modular development, global PACS) are closely related to the environment. Our personal experience began with the installation of a commercial system 10 years ago. With respect to sonography, picture archiving and communication systems allowed a more reliable and quicker retrieval of previous examinations, the immediate availability of images in different sites throughout the hospital and to avoid filming. About 70000 ultrasound examinations have been archived on optical disks, with a mean of ten images per investigation. Since November 1991, the picture archiving and communication system has been the only archive where such images can be found. The location of workstations in the wards allows the almost real-time availability of images and the immediate availability of reports right after typing. A questionnaire was given to all the hospital's clinicians and the following advantages were pointed out: no examination repetition, no unnecessary investigations, shortening of hospitalization time, impact on treatment choices. Our experience is going on with a new project, DPACS, providing all the services of the former system and offering a full integration with RIS both in the hospital and in the city areas and allowing communication between DICOM and non-DICOM compliant devices.

Safety profile of new non-ionic contrast media: renal tolerance.

The possible nephrotoxic potential of X-ray contrast media is one of the main concerns when testing new compounds. Iomeprol is a new nonionic monomeric contrast medium which has been tested during preclinical studies and clinical trials. Preclinical studies showed that the product has a renal tolerance comparable to that of other nonionic contrast media (iopamidol and iohexol) and less effects on renal histology than dimers like iodixanol and iotrolan. The clinical safety of the product has been evaluated during diagnostic procedures in more than 8000 patients and in particular renal function was studied in 988 patients. Results showed that iomeprol did not cause any alterations of clinical laboratory indices for renal function nor any cases of acute renal insufficiency.

Criteria for choice and use of contrast media in intra-arterial D.S.A.

The authors investigated the optimal characteristics of contrast media for use in intra-arterial DSA. 209 injections in 108 patients were evaluated, most of them in the abdominal and peripheral regions. In order to decrease contrast media osmolarity and obtain an adequate mixing with blood, contrast media with low iodine concentration were injected using the same volumes and flow rates of conventional arteriography. Good results were obtained with ionic contrast media, 100 and 150 mgI/ml. depending on the area investigated. The low concentrations allowed the use of ionic agents with an osmolarity very close to that of the non ionic contrast media: the pain has been eliminated and the heat sensation reduced. Furthermore the comparison with the cost of nonionic agents shows a great saving.

Intra-arterial digital angiography of the liver. Preliminary results.

The authors report the preliminary results of the intraarterial digital angiography of the liver. A series of 30 patients were examined comparing conventional and digital technique following the injection of the coeliac, splenic, hepatic and mesenteric arteries. The results obtained with the digital technique have been of good quality and sometimes even better in spite of significant dilution of the contrast medium. It is concluded that intraarterial digital angiography of the liver gives some advantages compared with the conventional technique, that is the use of a much lower concentrated contrast medium, the better visualization of the portal branches and its collaterals and the very low cost of the film material.

Digital subtraction angiography in postoperative evaluation of peripheral vascular disease.

The authors present the results of intravenous Digital Subtraction Angiography (DSA) in 41 patients examined after vascular surgery for peripheral disease. The digital technique has always been able to show the patency of the graft or the existence of complications (obstruction, stenosis, pseudoaneurysm), even in asymptomatic patients. The images were of good or excellent quality in 90% of the cases. The equipment with C-arm proved to be very useful for the oblique projections which were required in about 20% of the examinations.

Impact of technology and technique on the performance of the intravenous D.S.A. of the carotid arteries.

Intravenous Digital Subtraction Angiography (i.v. D.S.A.) was performed at the carotid bifurcation level in 259 patients with clinical or physical findings of a Cerebrovascular Insufficiency (C.V.I.). The angiographic examinations have been performed during two different periods, basically differing for the technology of the digital equipment and for the technique used. The personal experience showed how these two factors are important in determining the quality of the image and therefore the accuracy of the i.v. studies. Images of good quality of the common and internal carotid arteries have been obtained in 73% and 54% of the cases of the first period and in 93% and 82% of the cases of the second period. The role of the i.v. D.S.A. in the management of the C.V.I. depends not only upon the quality of the images, but also upon the surgical policy and from the availability of ultrasounds.

Routine evaluation of arteriopathies of the lower extremities by digital subtraction angiography.

Intravenous digital subtraction angiography (DSA) was performed in 119 patients with lower extremity ischemia using a 14" amplifier. Four injections of contrast medium were usually necessary for a complete evaluation of this vascular region. Images of good quality were obtained in most cases; movement artifacts and a faint opacification accounted for any poor results, which occurred mainly under the knee. The technique of pixel shifting turned out to be very useful to remove movement artifacts. The "measuring field" allowed us to minimize the problem of the inhomo geneous saturation of the amplifier. In 8% of the cases an intra-arterial DSA has been performed after an unsatisfactory intravenous examination. Conventional angiography appears to be no longer necessary.

The role of ultrasonography in the diagnosis of tumours of the renal pelvis.

The authors have evaluated 22 patients with renal pelvis tumour (RPT) by means of excretory urography and ultrasonography. Six patients also underwent arteriography. The value of the three investigations in the diagnosis of the lesion, the nature, the pyelic origin and the extension are presented. It is concluded that urography remains the method of choice for the evaluation of RPT while ultrasonography may be considered complementary to urography in cases of non-functioning kidney, when the urographic filling device defect is uncertain and in the differentiation between the pyelic or parenchymal origin of the tumour.