Ricostruzione tridimensionale dei vasi del collo

L'obiettivo di questo lavoro è stato quello di valutare l'efficacia della Angiografia tridimensionale TC (3D-TCA) in pazienti con patologia a carico del distretto carotideo extracranico. Sono stati esaminati 15 pazienti con stenosi di natura arteriosclerotica (14 casi) o arteritica (1 caso) a livello della biforcazione carotidea. Tutti i casi erano stati precedentemente indagati con arteriografia che è stata considerata il test di confronto. Le immagini tridimensionali, presentano una qualità molto valida e sono paragonabili a quelle angiografiche nella maggioranza dei casi. La tecnica 3D-TCA presenta a suo favore alcuni vantaggi: scarsa invasività; semplicità e rapidità di esecuzione; buona dimostrazione delle placche calcifiche che possono essere rimosse mediante software. I limiti attuali sono rappresentati da: necessità di una adeguata concentrazione di mezzo di contrasto nei vasi: possibili artefatti da calcificazioni e strutture ossee: mancanza di informazioni sul flusso dei vasi; difficile separazione tra arterie e vene in alcuni distretti; scarsa panoramicità rispetto alla angiografia.

Prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta and lower limbs

PURPOSE

The aim of this study was to assess the prevalence of extravascular collateral findings during 64-slice CT angiography of the abdominal aorta (AA-CTA) and lower limbs (LL-CTA).

MATERIALS AND METHODS

The images of 536 AA-CTA and LL-CTA examinations performed for suspected aortic and peripheral vascular disease in 500 patients were retrospectively reviewed. Two radiologists evaluated the 5-mm axial images independently using appropriate window settings for the area under investigation. Collateral findings were divided according to their clinical significance into significant, nonsignificant and meriting further investigation.

RESULTS

No collateral findings were identified in 97/500 patients (19.4%). In the remaining patients, 821 collateral findings were detected, of which 43 (5.24%) were classified as significant, 135 (16.44%) as meriting further investigation and 643 (78.32%) as nonsignificant. The findings indicative of the presence of a malignant lesion totalled 36 (4.5%).

CONCLUSIONS

AA-CTA and LL-CTA demonstrate a nonnegligible prevalence of collateral findings, many of them major. It therefore appears that the evaluation should focus not only on the image reconstructions to identify vascular disease, but also on the native axial images to detect incidental findings.

Virtual angioscopy by means of three-dimensional rotational angiography of the aortoiliac arteries

PURPOSE

The aim of this study was to report the different findings that can be visualised with virtual angioscopy starting from rotational angiography (RA) and three-dimensional (3D) image processing (3DRA) in the evaluation of the abdominal aorta and iliac arteries.

MATERIALS AND METHODS

Fifty-seven patients showing an occlusive or aneurysmal disease of the abdominal aorta and iliac arteries underwent intraarterial digital subtraction angiography (DSA) equipped with the RA function and a 3D workstation. We found that 3DRA is able to generate images of the examined vessels with a very effective 3D appearance; furthermore, it is able to create images of the lumen and wall of the vessel through two different modalities: endoviews and cross sections. The possibility of matching high-density structures (i.e. calcified plaques and stents) to standard 3D reconstructions of the examined arteries was applied.

RESULTS

Different aspects of the arteries can be demonstrated in the angioscopic elaborations: the normal and stenotic lumen, artery bifurcations, the collateral vessel origins and the severity and extensions of atheromatous calcifications and their relationships to the vessel wall. Virtual angioscopy is able to visualise some devices (catheters, stents) introduced during diagnostic and interventional procedures.

CONCLUSIONS

The constant technological evolution of diagnostic imaging is offering new image-processing techniques, providing new types of previously unexplored information. We present a summary of the different radiological findings that can be demonstrated with this new imaging technique.

Endovascular treatment of endoleaks after endovascular abdominal aortic aneurysm repair: personal experience

PURPOSE

This paper describes the different endovascular treatments (cuffs, endografts and embolisation) available for types I, II and III endoleaks occurring after endovascular abdominal aortic aneurysm repair (EVAR).

MATERIALS AND METHODS

From January 2000 to June 2006, 134 patients (118 men, 16 women; mean age 75.1 years) underwent EVAR. Ten patients (7%) developed significant endoleaks requiring endovascular treatment.

RESULTS

Five endoleaks were type I, two were type II and three were type III. Of the five type I endoleaks, four were proximal and one was distal. The proximal endoleaks were treated by cuff deployment, whereas the distal endoleak was treated with a bifurcated graft. Of the two patients with type II endoleak, one was treated by translumbar puncture and coil embolisation, and the other was treated by superselective embolisation of the lumbar feeding vessel with nonresorbable particles. Of the three patients with type III endoleak, two were treated by deploying an aortouniiliac endograft inside the bifurcated graft and the other by implanting a cuff to restore continuity between the graft body and the contralateral limb. Endovascular treatment was successful in 6/10 cases, whereas three cases required surgical conversion. One patient did not undergo surgery owing to poor general condition.

CONCLUSIONS

The reported incidence of endoleaks after EVAR is 10%-20%. Significant endoleaks should be treated promptly. Endovascular treatment can be done with different techniques, but success in not constant due to adverse anatomical conditions and technical difficulties.

Three-dimensional rotational angiography of the carotid arteries with high-flow injection from the aortic arch. Preliminary experience

PURPOSE

Three-Dimensional Rotational Angiography (3DRA) is a new technique based on a rotational angiographic acquisition able to display arterial vessels in a 3D rendering mode. The system was mainly developed for neuroradiological evaluations but preliminary extracranial experiences have also been reported. The aim of our work was to compare the results of three-dimensional angiography of the carotid arteries done with high-flow injection of contrast medium from the aortic arch with the results of selective angiography.

MATERIALS AND METHODS

Twenty patients underwent digital angiography of the supra-aortic vessels in order to quantify a stenosis of the carotid bifurcations previously detected at Doppler Ultrasound. Examinations were performed with the Philips Integris Allura system provided with the rotational angiography (RA) tool connected to a workstation for three-dimensional reconstruction able to display vessels in a 3D fashion (Volume Rendering, Gradient Rendering, Shaded Surface Display), automatically remove bone structures (cervical spine, calcified plaque, etc.) and perform an automatic analysis of the vessel diameter and surface area at the point of major stenosis and in the disease-free vessel segments above and below. The carotid evaluation was done either with selective catheterization and the two standard AP and LL projections and with RA after contrast medium injection from the aortic arch followed by 3D reconstruction.

RESULTS

The comparison of the selective angiography and three-dimensional images was possible in 37 out of 40 carotid bifurcations (3 internal carotid arteries were occluded) and a good diagnostic quality was obtained in 35 out of 37 cases with an high correlation in the degree of stenosis. In 2/37 cases with calcified plaques the degree of stenosis was effectively demonstrated only after electronic subtraction of the calcified component of the plaque.

CONCLUSIONS

The technique we propose proved to be feasible in all cases with a good correlation in the quantification of the degree of stenosis. The practical advantage of our technique is the almost complete exclusion of risks of neurological complications due to selective catheterization, and reduced examination time.

Rotational angiography of the carotid artery bifurcation: technical aspects and preliminary results

PURPOSE

Rotational Angiography (RA), a new modality for performing conventional catheter angiography, enables an accurate evaluation of the artery to be obtained from different points of view by means of the contemporary rotation of the X-ray tube and image intensifier during intrarterial selective injection of contrast media. This paper describes the examination technique and compares the diagnostic accuracy of the RA oblique projections with the data obtained in the antero-posterior (AP) and latero-lateral (LL) projections in the study of the carotid bifurcation.

MATERIALS AND METHODS

Thirty patients underwent RA of the supra-aortic vessels to evaluate the degree of a stenosis at the carotid bifurcation suspected at color Doppler imaging. The angiographic examinations were performed on a Philips Integris Allura system able to rotate the arc at a speed of 55 degrees /s with selective catheterisation of both common carotid arteries.

RESULTS

The frame showing the greatest degree of stenosis was compared with the frames obtained in the AP and LL projections. 57/60 carotid bifurcations were assessable (3 cases of internal carotid arteries were obstructed). The degree of stenosis evaluated on the most significant of the oblique projections was superior to that shown in the AP and LL projections for 16/30 cases on the right side and for 14/27 cases on the left side. In 4/57 cases (7%) the degree of stenosis was modified from less than 70% to more than 70%. No adverse event was observed due to catheterisation.

CONCLUSIONS

RA enables the complete three-dimensional evaluation of the carotid bifurcation, and generally yields more accurate information on the degree of the stenosis in comparison with AP and LL technique. The study was successfully carried out in all cases, however slightly longer examination times due to the setup requirements of the system. This was largely compensated by the quality of the information yielded, which required no additional projections to be performed. Moreover, the high frame rate of 25 frames per second showed the haemodynamic flow through the lesion.

Systemic and regional haemodynamic effects of aortofemoral angiography

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.

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.

Treatment options in Western hepatocellular carcinoma: a prospective study of 224 patients

BACKGROUND/AIMS

Though hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors in the world, the optimal therapeutic strategy is still poorly defined. This is mainly due to geographic differences in HCC which may affect the validity of treatment regimens in differents areas of the world. The aim of the present study was to analyze the natural course of the disease as well as to assess the efficacy of different therapeutical schemes in HCC observed in Ljubljana (Slovenia) and Trieste (Italy), two cities in Western Europe situated close to each other.

METHODS

During the period from January 1988 to December 1993, 224 consecutive patients (132 in Trieste and 92 in Ljubljana) with HCC were enrolled in the study. Patients were treated with the following 3 schemes: surgery 39 (17.4%), transcatheter chemoembolization (TACE) 116 (51.8%), and no treatment 69 (30.8%). The tumor was classified by Okuda staging and the liver disease by Child-Pugh score. Patients were followed up for 12-60 months, with an average of 40 months. The response rate to TACE and recurrence following surgery were evaluated. Comparative analysis of survival between different treatment groups was performed.

RESULTS

The natural course of the disease, and other characteristics of the HCC, showed a typical Western type of tumor. Liver disease was scored as Child A in 58%, Child B in 30% and Child C in 12%, and the tumor was staged as Okuda I in 52%, Okuda II in 37% and Okuda III in 11%, respectively. Treatment with TACE was followed by an objective response in 27%, with a median survival of 31 months. Surgery was followed by a recurrence rate of 77% within 19.5 months and median survival of 49 months. The overall median survival of nontreated patients was 8 months. Survival in each group of patients differed significantly between all three consecutive stages of Okuda (p<0.001). In contrast, the differences in survival were significant only between Child A and B (p<0.02). The differences between Child B and C were not significant.

CONCLUSIONS

This study emphasizes the importance of staging in the choice of treatment modality and diffusion of HCC in affecting an overall response to treatment and survival. Surgery is highly effective in monofocal HCC of Okuda I and II without cirrhosis. TACE is effective in Okuda I and II and Child A cirrhosis only. The treatment of HCC in Child B cirrhosis needs further studies. In Child C and/or Okuda stage III of HCC, any treatment except pure symptomatic relief is detrimental and should not be used.

[Endovascular treatment of isolated aneurysms of the hypogastric artery: technical considerations apropos of 2 cases]

Isolated aneurysm of the internal iliac artery is uncommon, with an incidence approaching 0.4%; its diagnosis is difficult; its natural course is progressive expansion and rupture. Two cases of hypogastric aneurysms, promptly treated with embolization, are reported. In selected patients the endovascular technique can represent a good alternative to the traditional surgical treatment that is associated with higher complication and mortality rate.

Valutazione ecografica e TC di pielonefrite acuta in paziente affetta da rene policistico

Autosomal dominant polycystic kidney disease is a rare nephropathy consisting of multiple cysts that alter almost all the parenchyma of the organ, leading to renal failure. A clinical case with atypical presentation is described.

"Aggressive" renal angiomyolipoma

PURPOSE

We describe the US and CT examinations of 4 patients with renal angiomyolipoma with an "aggressive" appearance, and review the literature.

MATERIAL AND METHODS

The imaging findings in 4 patients with benign renal angiomyolipomas associated with thrombosis of the renal vein and/or inferior vena cava are presented. In one case, enlarged lymph nodes at the renal hilum were found.

RESULTS

CT demonstrated fat densities within both tumor and thrombus. In one patient, small lymph nodes with low density internal areas were detected in the para-aortic region. When considering our patients together with those reported in the literature, we found that most angiomyolipomas with venous invasion were large and centrally located within the kidney. Venous thrombosis was observed in 9 lesions of the right kidney, and in only 4 of the left one; detection of the site of origin was impossible in one case. One patient only had symptoms due to the thrombus; 10 had problems due to the tumor; and 3 were asymptomatic. Only 4 patients with pararenal enlarged lymph nodes have been reported on in the imaging literature. Fat-containing nodes were detected by CT in one case only; the others had enlarged nodes of soft-tissue density. In one patient the diagnosis of hamartomatous lymph node invasion was established by angiography.

CONCLUSION

In patients with renal angiomyolipoma, demonstration of both fatty thrombus and the fatty infiltration of lymph nodes of the renal hilum cannot be regarded as an indication of malignancy, but only of local aggressive behavior. Although surgery is commonly contemplated to prevent symptoms from venous thrombosis, conservative treatment seems possible. Detection of enlarged lymph nodes of soft tissue density may cause difficult diagnostic problems, with the diagnosis addressed only by the presence of associated lesions. Increased awareness that renal angiomyolipoma can sometimes appear "aggressive" could help to prevent such lesions from being considered malignant, and thus avoid surgical confirmation of their nature.

Three-dimensional reconstructions of carotid bifurcation from CT images: evaluation of different rendering methods

Three-dimensional computed tomographic angiography (3D-CTA) and digital subtraction angiography of the cervical carotid artery were performed bilaterally in 15 patients with suspected stenoses. A new semi-automatic segmentation and new rendering methods were used. The degree of stenosis of internal carotid arteries, as determined both by axial slices and 3D images (surface, integral, maximum-intensity-projection, and raysum-rendered images), was compared qualitatively and quantitatively to angiographic findings. In correlation to angiography, the accuracy in determining the stenosis classification of internal carotid arteries was of 97% for axial slices and 59-90% for 3D images, respectively. Raysum (pseudoradiograph) rendering was found to be the most reliable rendering method and gave the most similar results to angiography. The accuracy of all rendering methods was improved by applying calcification removing algorithm, with a statistically significant difference between surface rendering without plaque removal and raysum rendering using the removing algorithm.

[Optimization of scanning and processing parameters for the three-dimensional reconstruction in computerized tomography of the facial bones]

The evolution of computer technology has significantly improved the performances of three-dimensional reconstructions from Computed Tomographic images. The authors discuss the examination technique and the modalities of three-dimensional reconstruction based upon a new advanced workstation. This unit is based on a Sun Sparkstation linked with the main computer of the CT scanner. The workstation is extremely fast, the processing time for a high resolution three-dimensional image of the maxillofacial region being about 3 minutes. The scanning parameters, image reconstruction and visualization were investigated on cases of maxillofacial (mainly posttraumatic) conditions. The most important scanning parameters are slice thickness, table incrementation, dose, scan plane. Slice thickness and table incrementation are the parameters bearing the greatest influence on the quality of the three-dimensional images. Dose is also important but bears no influence on image quality: therefore it can be kept as low as possible to reduce patient exposure. The scanning plane has some minor effect; coronal images have some advantages over axial images but in many cases only axial images can be acquired. The reconstruction parameters are the threshold and the matrix. The threshold may range 70 to 300 HU but in most cases ranges 120 to 200 HU. An advantage offered by this system is that it allows threshold values to be changed after the reconstruction has been completed, without performing a new reconstruction. The visualization parameters include four rendering methods, i.e. the surface mode, the integral mode, the maximum intensity projection and the ray sum. The surface mode is the one yielding the best results for bones while the others are used for the reconstruction of soft tissues and vessels. The workstation enables the three-dimensional images to be processed with shading parameters, and to be modified with cut planes, disarticulation methods and other interactive methods.

[Tridimensional reconstructions of intra- and extracranial arteries using computerized tomography]

Three-dimensional Computed Tomographic Angiography (3D CTA) is a new imaging technique for vascular structures. This study was aimed at investigating the diagnostic role of 3D CTA in the intracranial and extracranial arteries. Fifteen patients with intracranial artery disease (thirteen with aneurysms and two with arteriovenous malformations) and fifteen patients with stenosis of the common, internal or external carotid arteries underwent 3D CTA. All patients had been examined with intraarterial angiography. The CT examinations were performed with dynamic scanning during intravenous contrast agent administration. Three-millimeter thick contiguous slices were obtained in the cervical region and 1.5-mm contiguous slices in the intracranial region. CT findings were processed to produce 3D views on an independent workstation. 3D CTA results were compared with those of intraarterial DSA in all cases. Agreement was found in 13 of 15 cases of intracranial vascular abnormalities, and in 26 of the 30 carotid arteries in classifying the severity of the stenosis. The 3D views, which exhibit an excellent image quality, seem to be comparable to angiography in the intracranial and extracranial arteries. The main advantages of this technique are: 1) its low invasivity since only an intravenous contrast agent injection is required; 2) its easy and fast acquisition (2-3 minutes are needed if a non-spiral CT unit is used and less than one minute with spiral CT); 3) good demonstration of the calcified plaques which can be also removed with the softwares available at the workstation, to show the overall vessel lumen; 4) thanks to its simplicity the examination can also be performed in emergency (i.e. in patients with subarachnoid hemorrhage, if plain CT is positive for subarachnoid bleeding). Its main limitations are: 1) the need of an adequate concentration of contrast agent in the vessels; 2) artifacts due to calcified and bone structures; 3) no information about vessel inflow; 4) limited discrimination between arteries and veins in some areas (cavernous sinus); 5) limited field of view compared to angiography.

[Thin-section computerized tomography of the kidney in the differential diagnosis of small tumor and cystic hypodensities]

Small hypodense renal lesions with a round shape are frequently detected on CT scans of the upper abdomen after contrast medium administration. In nearly all cases these round hypodensities are simple small cysts with no clinical significance. However, the fluid density of these cysts cannot be always defined, due to the partial volume averaging which occurs on CT when 10-mm-thick slices and contrast enhancement are used. Therefore, a malignant tumor--i.e., small renal tumors or metastatic lesions--cannot be ruled out in some cases. Since the limitations of CT are related to partial volume averaging, the authors used both 5-mm and 10-mm slices to reduce this artifact. Forty-eight small hypodensities (< 15 mm) were studied after contrast agent administration: 42 of them were simple cysts and 5 were tumoral lesions--i.e., 3 renal cell carcinomas and 2 lymphomatous lesions. The results showed that, with 5-mm slices, the density of the fluid hypodensities decreased in nearly all cases and in 81.3% of cases it was below 30 HU. The difference in densities between 10-mm and 5-mm slices was about 50 HU (75 +/- 30 to 21 +/- 16 HU). In the 5 tumoral hypodensities, lesion density was still in the soft tissue range also with 5-mm slices, with no major decrease. These results show that this technique is simple and effective in the differential diagnosis of small renal hypodensities since it requires only a short additional examination time.

[Arterial anatomy of the celiac trunk and the superior mesenteric artery with computerized tomography]

A hundred patients with different conditions underwent CT and the results were retrospectively reviewed to evaluate the visibility of the celiac trunk, of its branches and of the superior mesenteric artery. Thirty-six patients underwent angiography too, which allowed the anatomical variants suspected on CT to be demonstrated, according to Kuhns' criteria. The other 64 patients were consecutively selected and only aneurysmal changes were not included. All examinations were performed using a General Electric 9800 Advantage scanner, with 2 second scanning time and 10 mm-thick contiguous scans. In 20 patients 5 mm contiguous scans were performed. All examinations followed i.v. injections of contrast agents which were given with an automatic injector. The cases with suspected anatomical variants on CT but with no angiographic confirmation were not considered. A hundred CT exams were retrospectively reviewed: the celiac trunk and the common hepatic artery were demonstrated in all of them. Visibility of the other branches was 40% for the hepatic artery, 53% for the right branch of the hepatic artery and 39% for its left branch, 70% for the gastroduodenal artery, 82% for the left gastric artery, 97% for the splenic artery and 100% for the superior mesenteric artery. As for the 36 patients who underwent both CT and angiography, right hepatic artery from the superior mesenteric artery was seen in 19% of cases with both modalities; common hepatic artery arising from the superior mesenteric artery was detected in 2% of cases. In both instances, these anatomical variants appeared as a vessel running posterior to the portal vein. The careful investigation of axial CT scans showed the level of origin of the artery from the superior mesenteric artery. These results are in agreement with the angiographic data reported in the literature. Our study demonstrated that the celiac trunk and its variants are always depicted by the new CT scanner. The knowledge of these variants may be useful in the patients to submit to liver surgery. The celiac trunk and its variants are demonstrated with conventional 10 mm slices. The use of 5 mm slices improves the visibility of thin anatomical branches but is not essential to recognize the major vessels and anatomical variants.

[Computerized tomography: problems and errors in the diagnosis of renal masses]

The diagnostic imaging of renal masses has greatly benefitted from US and CT. Nevertheless, a certain number of problems and errors are still present, and they must be discussed once more. In the authors' experience, problems and errors have 3 fundamental causes: operator, examination technique and complex patterns of renal masses. The latter is the most important cause of error in CT diagnosis. Complex patterns are seen in a limited number of cystic masses--i.e., hemorrhagic, inflammatory, and septated cysts, and cystic tumors. Hemorrhagic cysts, if hemorrhage is not recent, can cause some diagnostic difficulties since the typical high density of the recent hemorrhage is no longer present. Other renal masses may appear hyperdense on unenhanced CT scans, and therefore they must be considered in the differential diagnosis. Inflammatory cysts and abscesses are sometimes difficult to differentiate from other masses due to their aspecific appearance; clinical correlation is important in these instances to support CT diagnosis. Multiseptated cysts and cystic tumors cause huge problems of differential diagnosis. A good knowledge of differential CT findings is sure to reduce the problems in differentiating benign from malignant tumors and, among the latter, the different histotypes and metastases, when present as solitary masses. Also in this case, the correlation between CT, clinical history and other modalities can reduce the number of questionable cases.

[Computerized tomography of the spine in the evaluation of multiple myeloma]

Computed Tomography (CT) of the spine was performed on 17 patients with myeloma in order to assess the role of the technique in recognizing and evaluating the extent of the lesions. Myelomatous lesions followed two patterns at CT: first of all, multiple focal lesions, whose density is either solid, liquid, or fatty; second, an extensive pattern involving the spongiosa of the vertebra, including the posterior arch. CT detected more lesions than conventional radiology; furthermore, the extent of the lesions was much better demonstrated by CT. CT should thus be performed: a) in case of pain and/or neurological findings in negative radiological examinations; b) to evaluate the extent of myelomatous lesions (mainly in the spine); c) in solitary myeloma CT may be performed on different bone segments with clinical symptomatology but normal X-ray findings.

Three-dimensional computed tomography of the acetabulum

Acetabular fractures represent a complex variety that are classified in different types. Conventional radiology is often inadequate to demonstrate and classify the fractures. Computed tomography (CT) has already been shown to be superior in this field. A further advantage of CT is represented by the recent availability of three-dimensional (3D) images that are realized from axial CT scans by means of a new software. The Authors report the applications of this new software to the study of the normal acetabulum and in patients with fractures. 3D images allows an effective demonstration of the fracture, its irradiation and the dislocation of bone fragments. The information is contained in one or few images rather than many axial images. Therefore the role of 3D images may be considered complementary to axial CT scans.

[3-dimensional craniofacial computerized tomography]

Computed tomography allows today to reconstruct three-dimensional (3D) images from axial scans. The authors report their experience in cranio-facial pathology achieved in two Departments of Radiology (University of Trieste, Italy and University of Stanford, California). 3D images have been realized using two different softwares, one of which allows to reconstruct both soft tissue and bone structures. The applications in maxillo-facial traumas, cranio-facial malformations and head tumours are discussed. 3D images turned out to be very useful for the optimal visualization and for the spatial demonstration of the lesion and have potential applications in cranio-facial surgery and radiotherapy.

[Adrenal tuberculosis in 13 patients with Addison's disease. CT findings]

A series of thirteen cases of adrenal tuberculosis with Addison's disease is presented. At the onset of disease, CT findings consisted of an enlargement of both glands, with peripheral enhancement after contrast medium was injected. The CT differential diagnosis among tubercular, metastatic and amyloidotic etiology was not possible. When the course of the illness was favourable, CT showed a generalized glandular atrophy with calcifications. In two fatal cases, the diagnosis could be made only at post-mortem examination.

Computed tomographic follow-up in a case of Addison's disease

Addison's disease of the adrenal glands presents with different pathological findings depending on the stage. In the acute phase the adrenal glands are bilaterally enlarged while in the chronic phase the glands are small and calcified. A case of Addison's disease with follow-up over a period of a year by CT is reported. CT showed the evolution of the adrenal glands from bilateral masses to small calcified glands. The differential diagnostic problems in the acute phase are also discussed.

[Computed tomography of the femur head. Normal aspects and appearance in aseptic necrosis]

The diagnostic value of Computed Tomography (CT) in the diagnosis of the aseptic necrosis of the femoral head is discussed. The CT findings in the different evolutive stages are reported and the respective diagnostic value of Conventional Radiology and CT are discussed. The CT findings of femoral head necrosis in the early phases are emphasized. The capability of CT to demonstrate structural changes in femoral heads with regular morphology allows to consider this technique when there exists a clinical doubt of osteonecrosis of the femoral head and in risk patients.