Gadolinium-enhanced 3D MRA of the aortic arch vessels in the detection of atherosclerotic cerebrovascular occlusive disease

PURPOSE

Our goal was to evaluate non-breath-hold Gd-enhanced 3D MR angiography (MRA) for the detection of atherosclerotic occlusive disease of the aortic arch vessels and to compare image quality with two breath-hold techniques.

METHOD

One hundred sixty consecutive patients with known or clinically suspected atherosclerotic cerebrovascular occlusive disease underwent Gd-enhanced 3D MRA of the aortic arch and great vessels. One hundred twenty-six examinations were performed with the body coil after infusion of 40 ml of Gd-DTPA; 89 of these were performed without breath-holding and 37 were acquired during suspended respiration. Thirty-four examinations were performed in a body phased-array coil with breath-holding, a timing examination, and 20 ml of contrast agent by manual (n = 17) or power (n = 17) injection. Images were evaluated for the presence of blurring and ghosting artifacts and venous enhancement. Of the 27 patients who underwent non-breath-hold MRI and digital subtraction angiography (DSA), two readers blinded to the DSA results retrospectively evaluated the MRA examinations for the presence of occlusive disease of the innominate, carotid, subclavian, and vertebral arteries. DSA correlation was not evaluated for the 71 breath-hold studies.

RESULTS

Sensitivity and specificity for arch vessel occlusive disease with non-breath-hold MRA were 38 and 94% for Reader A and 38 and 95% for Reader B. Breath-holding significantly reduced blurring and ghosting artifacts (p < 0.001) when compared with non-breath-hold imaging, and use of 20 ml of contrast medium, with a timing examination, resulted in significantly less venous enhancement than seen with 40 ml (p < 0.001).

CONCLUSION

Non-breath-hold Gd-enhanced 3D MRA is insensitive for detecting arch vessel occlusive disease. Breath-hold imaging, in conjunction with a timing examination and a lower dose of contrast agent, improves image quality, but further studies are needed to assess diagnostic accuracy.

Helical CT angiography of living renal donors: comparison with 3D Fourier transformation phase contrast MRA

PURPOSE

The purpose of this study was to determine whether helical CT angiography (CTA) or MR angiography (MRA) is the optimal method to use as a preoperative examination for anatomic arterial assessment of living renal donors.

METHOD

Eighteen candidates to be renal donors underwent helical CTA, 3D Fourier transformation phase contrast (3D-FT-PC) MRA, and digital subtraction angiography (DSA). The CTA and MRA were interpreted separately by three readers independently, and these results were correlated with the findings of DSA.

RESULTS

DSA showed nine accessory renal arteries and 10 prehilar branches. CTA revealed seven or eight accessory renal arteries. MRA showed six or seven accessory arteries. Of 10 prehilar branches, 7-9 branches were detected with CTA and 5-8 branches with MRA.

CONCLUSION

Helical CTA is superior to 3D-FT-PC MRA for evaluating the arterial anatomy of living renal donors.

[Angiography during interventional procedures with carbon dioxide (CO2) (carbo-angiography) in patients with increased contrast media risk]

Within the last 18 months we examined 130 patients with known complications or contraindications using iodinated contrast media for angiography by using carbon dioxide as contrast agent in digital subtraction angiography technique. These were diagnostic pelvis-leg angiographies (n = 106) with simultaneous consecutive interventional radiologic therapy in 68 cases. In 19 dialysis access fistulas 11 angioplasties were performed in the same session. In 5 cases of renal allografts no interventional radiologic therapy was necessary. For CO2 application an electronic controlled special injector was used. Carbon dioxide has a number of advantages: no adverse reactions, nonallergenic and can be used several times without increasing risks and is cost-saving. CO2 angiography is a sensitive method, for detection vessel wall processes below the diaphragm. It can replace conventional angiography.

Subtraction CT angiography with controlled-orbit helical scanning for detection of intracranial aneurysms

PURPOSE

Our goal was to evaluate the utility of subtraction three-dimensional CT angiography for the detection of intracranial aneurysms.

METHODS

Thirty-six patients with intracranial aneurysms were examined using newly devised controlled-orbit helical scanning and conventional angiography. Three-dimensional CT angiograms and subtraction 3-D CT angiograms were compared with conventional angiograms for their characterization of intracranial aneurysms.

RESULTS

Fifty aneurysms were depicted on conventional angiograms, of which 48 (96%) were seen on the 3-D CT angiograms. Three-dimensional CT angiography was superior or equivalent to conventional angiography for depicting the shape, direction, and location of 33 (66%) of 50 aneurysms; however, it was often less useful than conventional angiography in delineating intracranial aneurysms adjacent to bone. Subtraction 3-D CT angiograms were obtained in 32 patients with a total of 46 aneurysms (in four cases, aneurysms were not depicted owing to excessive motion artifacts), and were superior or equivalent to conventional angiograms in all 46 cases.

CONCLUSIONS

Subtraction 3-D CT angiography with the use of controlled-orbit helical scanning is effective in the detection of intracranial aneurysms.

[Digital subtraction arterioportography in the examination of patients with the portal hypertension syndrome]

Based upon data of 107 angiographic examinations in the regimen of digital subtraction the authors propose a regional program of angiographic examinations of patients with the syndrome of portal hypertension including the digital subtraction recurrent celiac and mesenteric portography, terminal occlusive flebohepatography. The given complex of investigations allows the determination with a minimum traumatic action of the form of portal hypertension and selection of the best for each patient kind of operative intervention. The article describes the methods of angiographic examinations improved and adapted by the authors for diagnosing the syndrome of portal hypertension. Criteria for the assessment of the results obtained are proposed. The use of digital subtraction arterioportography in complex with digital occlusive flebohepatography allows the main problems facing the surgeons when choosing the kind of operative interventions for patients with portal hypertension to be solved.

Three-dimensional vascular reconstruction with a clinical x-ray angiography system

RATIONALE AND OBJECTIVES

The authors developed a technique to produce high-resolution, three-dimensional images of vasculature from a set of x-ray projections in an attempt to provide detailed anatomic representations of complex vasculature.

MATERIALS AND METHODS

Projection images were acquired with a clinical angiographic system by using biplanar rotational digital subtraction angiography. The images were reconstructed with an additive algebraic reconstruction technique.

RESULTS

The feasibility of the technique was tested by reconstructing three-dimensional images of several phantoms, including a wire phantom and an anatomic flow phantom. The anatomic phantom allowed replication of contrast material flow and image noise that are characteristic of patient examinations. The reconstruction procedure was then used to examine a carotid artery and a cerebral aneurysm in two patients.

CONCLUSION

A method of reconstructing vasculature from x-ray angiograms has been developed and validated with geometric and anatomic phantoms. Preliminary patient applications indicate that this technique enables enhanced visualization of complex vascular relationships and structures.

Depth separation in ten observers with a new stereoscopic X-ray acquisition system

The aim of this work was to assess the depth separation of a new X-ray digital stereo angiographic system through visualization on a stereoscopic monitor. Before starting the clinical trial of this new stereo-digital angiographic system, it seemed to us mandatory to assess the inherent performance of the system to depict depth information, as well as the ability of the users to work with it. With this idea we designed a global test based on the observation of a physical test object by the potential users of the system, during a session long enough to simulate an angiographic study. The acquisition system consisted of a twin focal-spot X-ray tube and a standard DSA DG 300 (General Electric/CGR). The stereo display was controlled by a liquid crystal modulator placed in front of a black-and-white monitor. Special polarized glasses worn by the observers allowed right- and left-image separation. Depth separation was measured in ten observers by means of a stereoscopic test object. Six of the ten observers were able to locate accurately three-dimensional patterns separated by a 12- to 1.5-mm gap. No learning effect was noticed. This result suggested that stereo display through wireless polarized glasses coupled to up-to-date digital subtraction angiography technology may provide an accurate and ergonomic way to a dimensional enhancement of X-ray angiography.

[The angiography of kidney transplant arteries using carbon dioxide]

BACKGROUND AND OBJECTIVE

After renal transplantation hypertension occurs in 60-80% of patients, in 3-23% of them due to renal artery stenosis in the transplanted kidney. Angiographic assessment of the severity of the stenosis would best be done with a non-nephrotoxic contrast medium. We investigated the use of carbon dioxide, a bubble-forming contrast medium excreted via the lung, for its suitability in the angiography of the arterial system in the renal transplant.

PATIENTS AND METHODS

In an uncontrolled series of observations on six patients with renal transplants and hypertension who were being treated with three or four antihypertensive drugs, the transplant's arteries were demonstrated with carbon dioxide, injected by Seldinger technique into the ipsilateral femoral artery, and the results recorded by subtraction angiography.

RESULTS

The angiograms demonstrated postoperative kinked renal artery, a plaque in the external iliac artery, and a sharply angled origin of the external iliac artery in one case each, and three normal cases.

CONCLUSIONS

Carbon dioxide is a suitable medium for demonstrating renal arteries in a transplanted kidney and is preferable to conventional contrast media for the angiographic diagnosis of possible renal artery stenosis.

CT angiography using electron-beam computed tomography (EBCT): a phantom study

The purpose of this study was to evaluate the accuracy of CT angiography in small vessels using electron-beam computed tomography (EBCT). Vessel phantoms with inner diameters of 8 mm, 6 mm, and 4 mm were prepared with segments of 75%, 50%, and 25% stenosis in each vessel. The vessels were filled with contrast medium (Iopamidol 300 at 1/24 dilution, approximately 380 HU). The EBCT apparatus used was an Imatron C- 150. The step volume scan mode was used with slice thicknesses of 1.5 mm and 3.0 mm, scan time of 0.3 sec, and 210 mm field of view. Images with a slice thickness of 1.5 mm were definitely better than those with a slice thickness of 3.0 mm. The quality of maximum intensity projection (MIP) images was quite similar to that of three-dimensional (3D) images. Using the 8 mm vessel phantom, all stenotic segments were accurately visualized on CT angiography. The 50% stenotic segments were accurately estimated in all vessels. However, the 75% stenotic segments were slightly overestimated in smaller vessels, and the 25% stenotic segments were slightly underestimated in smaller vessels. We consider CT angiography using EBCT to be a useful, less invasive diagnostic modality for stenoocclusive lesions.

Cerebral CT angiography in the diagnosis of acute subarachnoid hemorrhage

PURPOSE

To evaluate the usefulness of CT angiography (CTA) in the detection of intracranial aneurysms in patients with acute subarachnoid hemorrhage (SAH).

MATERIAL AND METHODS

In 53 patients with nontraumatic SAH a helical contrast-enhanced CTA was performed. CTA data were reconstructed with maximum intensity projection (MIP). Each patient underwent selective arteriography of the cerebral vessels (as the gold standard). CTA (axial images and MIP reconstructions) and arteriography were evaluated separately and their diagnostic information was compared.

RESULTS

In 14 of the 53 patients neither CTA nor angiography showed a vascular malformation. In the remaining 39 patients, angiography demonstrated a total of 51 aneurysms ranging in size from 3 mm to 16 mm. CTA missed one of these aneurysms, which was located at the internal carotid artery. 3-D CT reconstruction was slightly superior to arteriography in the demonstration of the neck, shape and direction of the aneurysms. Partial thrombosis of 3 aneurysms was demonstrated only by CTA.

CONCLUSION

Although CTA cannot replace cerebral arteriography in the diagnostic work-up of acute SAH, it proved to be helpful in demonstrating the topographic anatomy of cerebral aneurysms and surrounding structures.

Monochromatic energy-subtraction radiography using a rotating anode source and a bent Laue monochromator

A system for area-beam energy-subtraction monochromatic radiography was developed and tested. It utilizes a bent Laue crystal monochromator developed at the National Synchrotron Light Source (NSLS), and a compact rotating anode X-ray source developed at the Science Research Laboratory (SRL). The K(alpha) characteristic lines (both K(alpha 1) and K(alpha 2) of the cerium and barium targets were diffracted by the monochromator and used for the above- and below-K-edge imaging, respectively, of phantoms with iodine contrast agents. Digital subtraction of the images produced an iodine image.

[A report on experience with a second-generation PACS installation in routine computed tomographic operations]

PURPOSE

Our institute has been using a pilot SIENET-PACS system for the last five years; its advantages and disadvantages in daily use are described.

MATERIAL AND METHODS

The SIENET system connects 2 CT, 3 MRT and 2 angiographic installations with 7 viewing consoles and with an optical archive. From January 1994 to 1997 approximately 19,000 patients were examined by CT and the results stored digitally in the PACS system.

RESULTS

A representative analysis of selected patient data revealed problems in 12.8% of patients with regard to the radiological information system and also the hospital information system. While the digital data proved satisfactory, the production of digital images was excellent but time-consuming. The image archive was reliable but required greater capacity for our purposes.

CONCLUSIONS

Manual retrieval of patient data presented problems and integration of the radiology information system and PADS is essential. Digital data gathering is an advantage. Digital imaging is too slow and should be improved by more suitable software. Integration of new archival storage methods and compatibility with the DICOM standard is, judging form our experience, essential.

[The study of a frameless stereotactic localization method using DSA]

A frameless stereotactic localization method with DSA is introduced in this paper. A locating plate and four head marks are used in the method. Using two projection images of DSA, the three dimension coordinate of any point can be calculated referring to the reference locating coordinate system. The method is the theoretic basis of locating brain structure such as the blood vessel using DSA.

[Digital subtraction angiography with carbon dioxide using a new gas dosage system]

PURPOSE

The clinical evaluation of digital subtraction angiography with carbon dioxide using a newly developed low-tech CO2 dosage and injection system.

METHOD AND PATIENTS

The hand-held system (CO2 angio set) consists of a dosage chamber in connection with a special stopcock to apportion the gas. By optimising injection volume and pressure steady gas flow characteristics are approximated. A safety design prevents unintentional gas injection. CO2 arteriographies were performed on 185 patients. Main indications were renal insufficiency and a history of adverse reactions to iodinated contrast media. In patients with femoral cannula access, catheterless reflux angiography was performed.

RESULTS

The injection system provided complete and coherent visualisation of the abdominal aorta, visceral, pelvic, and lower limb arteries via catheter (71 cases) or via femoral cannula using reflux technique (114 cases). Stenoses, occlusions, and collaterals were assessable. Employing the gas reflux over the aortic bifurcation bilateral run-off studies up to the calf trifurcation were performed via unilateral femoral cannula. Use of a dedicated stacking software improved image quality of distal femoral, popliteal and calf arteries.

CONCLUSION

The CO2 management system allows adequate imaging of the arteries below the diaphragm. Ease and safety of use and low costs are advantageous.

[Studies of image quality and dose in digital subtraction angiography]

METHODS

The dose needed for high image quality in l.a. DSA, was determined by investigation of the necessary relationship between dose and image quality. This method is based on measurements of the signal-to-noise ratio and of the contrast-detail detectability. It has been tested on two different systems (Philips integris V3000, Philips Diagnost 97).

RESULTS

Our measurements prove that an image intensifier entrance dose of 1.1 microGy (image intensifier diameter 38 cm) is sufficient for high image quality in DSA. An increased dose value does not lead to an improvement in image information. For details larger than the pixel size the 512 matrix produces a higher signal-to-noise ratio with a higher contrast-detail detectability, whereas higher spatial resolution results by the use of a 1024 matrix. In rotational angiography, high image quality can be achieved at an image intensifier entrance dose of 1.1 microGy. In contrast to sequences without rotation, image quality is decreased through movement unsharpness. As the maximum exposure time 25 ms should be selected. The use of a 1024 matrix does not lead to a better spatial resolution in rotational angiography.

Three-dimensional computed tomographic angiography in detection of cerebral aneurysms in acute subarachnoid hemorrhage

OBJECTIVE

Three-dimensional computed tomographic angiography (CTA) is a recently developed imaging modality. We demonstrate the value of this noninvasive method in replacing digital subtraction angiography (DSA) in the detection of aneurysms of the circle of Willis in patients with subarachnoid hemorrhage admitted to our institution.

METHODS

A helical acquisition was performed for computed tomographic scans obtained for 120 patients with a 1 mm per second table speed and a 1-mm collimation, 1:1 pitch. Axial source images were transferred on a console Advantage Windows workstation (General Electric, Milwaukee, WI) and CTA was obtained using maximum intensity projection reconstruction. All patients had undergone DSA of the circle of Willis (80 patients preoperatively and 40 postoperatively).

RESULTS

A total of 129 aneurysms were detected in 107 patients. Three-dimensional CTA disclosed nothing abnormal in 13 patients. Ninety-two patients sustained one aneurysm, 10 patients sustained two, 3 patients sustained three, and 2 patients sustained four. All results were confirmed by DSA. In two cases, aneurysms of the middle cerebral artery were defected by CTA but not by DSA. When using angiographic views, the aneurysm was always masked by a branch of the middle cerebral artery.

CONCLUSION

The sensitivity of three-dimensional CTA is comparable with that of DSA, and its specificity is 100%. Because CTA is simple, quick, noninvasive, and reliable, we think that it can eventually replace DSA.

[Digital dacryography after insertion of silicone probes after interruption of the lacrimal ducts in childhood]

Digital dacryography with image subtraction permits a very detailed visualization of the lacrimal pathway, evaluating long-term results of emergency surgery on resected lacrimal canaliculi with silicon probe in children. 65 pediatric patients with traumatic injuries of the eyelid have been treated in emergency surgery with introduction of a silicon catheter. 28/65 patients presented in follow-up the symptom of the "wet-eye": 13 of these patients have been examined with digital dacryography. The examination has permitted exclusion of an organic stenosis or a post-surgical complication of the reconstructed tear duct. The results suggest that the symptom of the "wet-eye" may be explained by a loss of the suction mechanism of the lacrimal papilla.

Computed radiography angiography using storage phosphor imaging plates: eight year's experience

We reviewed the indications, modalities, and quality of angiographic examinations performed in our department from 1987 to 1994 and compared the image characteristics and technical convenience of three modalities: conventional film-screen angiography, fluorographic digital subtraction angiography (F-DSA), and computed radiography angiography using biplane rapid changers of storage phosphor imaging plates (IP-CRA). IP-CRA has practically eclipsed conventional film-screen angiography in our radiology department. Sixty-percent of the total 700 examinations carried out in 1994 were performed using a combination of IP-CRA and fluorographic digital subtraction angiography (F-DSA). The remainder were performed with F-DSA alone. The post-processing functions of IP-CRA like subtraction and change of contrast or density were useful especially in such regions as pulmonary, bronchial, or external carotid arterial territories, where high natural contrast made image processing difficult with both F-DSA and film-screen angiography. The spatial resolution of IP-CRA was superior to that of F-DSA and comparable to the film-screen method. It was concluded that angiography using imaging plates was a useful part of the digital radiography system.

[New developments in parameter-oriented roentgen densitometry perfusion analysis within the scope of heart catheter studies]

X-ray densitometric evaluation of digital subtraction coronary arteriograms allows a qualitative and quantitative detection of contrast medium propagation through the epicardial coronary arteries, the capillary system and the coronary venous system. So-called "time-density-curves" (TDCs) can be generated following Lambert-Beer's law similar to indicator dilution curves by using contrast medium as the indicator. Several time and density parameters can be derived from these TDCs, which are related to local myocardial perfusion. Different animal validation studies have shown the applicability of this concept for in-vivo evaluation of coronary blood flow and myocardial perfusion. Nevertheless, absolute measurement of volumetric coronary blood flow or myocardial perfusion failed. Therefore, relative changes in coronary blood flow or myocardial perfusion in response to pharmacologically induced maximum hyperemia were measured and coronary or myocardial perfusion reserve was calculated as the ratio of hyperemic flow or perfusion divided by baseline values. Despite theoretical attractions for an application during routine cardiac catheterization, this densitometric approach did not get a wide acceptance. Primary reason for this limited use in specialized centers was the time consuming process of densitometric evaluation of the subtraction coronary arteriograms, which require digital cine angiography and necessitates enormous computer hard ware. This main limitation has been overcome since more powerful computer hard ware (processor speed, hard disk space, digitization boards) has become rapidly available during the last years at more moderate pricing and digital techniques today are state of the art in cardiac catheterization laboratories. In addition, soft ware program packages allowed an automatization of the digitization and densitometric evaluation process. These programs include ECG triggered cine image digitization with improved temporal resolution, semiautomatic definition of regions-of-interest including definition of reference regions-of-interest for the detection of background density changes and quality-controlled densitometric parameter analysis. This progress made an application during routine cardiac catheterization feasible. In animal validation studies this improved X-ray densitometric approach for evaluation of local myocardial perfusion was validated versus colour-coded microsphere techniques. The time parameter "rise time", defined as the time from the start of local contrast medium induced density change to its maximum revealed a close correlation (r2 = 0.965) to the results of the microsphere technique over a wide range of perfusion. We have applied this technique before and after coronary interventions such as balloon angioplasty and stenting. Results documented an improvement of poststenotic myocardial perfusion reserve immediately after coronary balloon angioplasty and an additional improvement after adjunct coronary stenting. Only after stenting but usually not after coronary balloon angioplasty alone poststenotic myocardial perfusion reserve gained the intraindividual reference level, measured in a perfusion bed supplied by an epicardial coronary artery without stenoses. These results documented the functional benefit of coronary stenting on poststenotic myocardial perfusion in addition to the well known morphologic benefit with the creation of a larger and more circular conduit.

[3D-CT angiography and duplex sonography compared to arteriography in carotid stenoses]

PURPOSE

To determine the value of 3D-CT angiography, duplex sonography in comparison to selective digital subtraction angiography for evaluation of carotid artery stenoses.

METHODS

30 patients with 51 stenoses of carotid artery underwent 3D-CT angiography, duplex sonography and angiography. Quantification of stenosis was determined according to the NASCET study and categorized into mild (0-29%), moderate (30-69%), severe (70-99%) and occluded (100%).

RESULTS

The agreement of 3D-CT angiography with intraarterial digital subtraction angiography (DSA) was 62% (r = 0.89; p < 0.0001) and of duplex sonography with DSA was 77% (r = 0.94; p < 0.0001). Both modalities underestimated one occlusion as stenosed. In the evaluation of moderate and severe stenoses 3D-CT angiography showed an agreement with DSA in 50% (duplex: 88%) and 55% (duplex: 89%) respectively and was inferior to duplex sonography.

CONCLUSION

3D-CT angiography is inferior to duplex sonography in the evaluation of carotid stenosis and not useful as a screening or reference examination.

[Instrumental diagnosis for therapeutic decision: intra-arterial DSA versus 3D CT-angiography in abdominal aortic aneurysms]

Compared to intraarterial DSA, 3D spiral CT-angiography could be an reliable alternative method for preoperative evaluation and planning of abdominal aortic aneurysms. 3D data reconstruction with new rendering techniques (especially "volume rendering") provides unique information about mural thrombus, calcified plaques, vessel kinking and renal/visceral arteries. However, the more invasive intraarterial DSA should be performed in patients with complex occlusive disease of the iliac arteries, renal or visceral artery stenoses, or pathological findings in peripheral duplex sonography or if intraluminal exclusion with endostent placement is planned.