VOR gain calculation methods in video head impulse recordings

BACKGROUND: International consensus on best practices for calculating and reporting vestibular function is lacking. Quantitative vestibulo-ocular reflex (VOR) gain using a video head impulse test (HIT) device can be calculated by various methods. OBJECTIVE: To compare different gain calculation methods and to analyze interactions between artifacts and calculation methods. METHODS: We analyzed 1300 horizontal HIT traces from 26 patients with acute vestibular syndrome and calculated the ratio between eye and head velocity at specific time points (40 ms, 60 ms) after HIT onset (‘velocity gain’), ratio of velocity slopes (‘regression gain’), and ratio of area under the curves after de-saccading (‘position gain’). RESULTS: There was no mean difference between gain at 60 ms and position gain, both showing a significant correlation (r2 = 0.77, p < 0.001) for artifact-free recordings. All artifacts reduced high, normal-range gains modestly (range –0.06 to –0.11). The impact on abnormal, low gains was variable (depending on the artifact type) compared to artifact-free recordings. CONCLUSIONS: There is no clear superiority of a single gain calculation method for video HIT testing. Artifacts cause small but significant reductions of measured VOR gains in HITs with higher, normal-range gains, regardless of calculation method. Artifacts in abnormal HITs with low gain increased measurement noise. A larger number of HITs should be performed to confirm abnormal results, regardless of calculation method.

Impact of artifacts on VOR gain measures by video-oculography in the acute vestibular syndrome

OBJECTIVE

The video head impulse test (HIT) measures vestibular function (vestibulo-ocular reflex [VOR] gain - ratio of eye to head movement), and, in principle, could be used to make a distinction between central and peripheral causes of vertigo. However, VOG recordings contain artifacts, so using unfiltered device data might bias the final diagnosis, limiting application in frontline healthcare settings such as the emergency department (ED). We sought to assess whether unfiltered data (containing artifacts) from a video-oculography (VOG) device have an impact on VOR gain measures in acute vestibular syndrome (AVS).

METHODS

This cross-sectional study compared VOG HIT results 'unfiltered' (standard device output) versus 'filtered' (artifacts manually removed) and relative to a gold standard final diagnosis (neuroimaging plus clinical follow-up) in 23 ED patients with acute dizziness, nystagmus, gait disturbance and head motion intolerance.

RESULTS

Mean VOR gain assessment alone (unfiltered device data) discriminated posterior inferior cerebellar artery (PICA) strokes from vestibular neuritis with 91% accuracy in AVS. Optimal stroke discrimination cut points were bilateral VOR gain >0.7099 (unfiltered data) versus >0.7041 (filtered data). For PICA stroke sensitivity and specificity, there was no clinically-relevant difference between unfiltered and filtered data-sensitivity for PICA stroke was 100% for both data sets and specificity was almost identical (87.5% unfiltered versus 91.7% filtered). More impulses increased gain precision.

CONCLUSIONS

The bedside HIT remains the single best method for discriminating between vestibular neuritis and PICA stroke in patients presenting AVS. Quantitative VOG HIT testing in the ED is associated with frequent artifacts that reduce precision but not accuracy. At least 10-20 properly-performed HIT trials per tested ear are recommended for a precise VOR gain estimate.

Design, simulation and evaluation of uniform magnetic field systems for head-free eye movement recordings with scleral search coils

The precise measurement of eye movements is important for investigating vision, oculomotor control and vestibular function. The magnetic scleral search coil technique is one of the most precise measurement techniques for recording eye movements with very high spatial (≈ 1 arcmin) and temporal (>kHz) resolution. The technique is based on measuring voltage induced in a search coil through a large magnetic field. This search coil is embedded in a contact lens worn by a human subject. The measured voltage is in direct relationship to the orientation of the eye in space. This requires a magnetic field with a high homogeneity in the center, since otherwise the field inhomogeneity would give the false impression of a rotation of the eye due to a translational movement of the head. To circumvent this problem, a bite bar typically restricts head movement to a minimum. However, the need often emerges to precisely record eye movements under natural viewing conditions. To this end, one needs a uniform magnetic field that is uniform over a large area. In this paper, we present the numerical and finite element simulations of the magnetic flux density of different coil geometries that could be used for search coil recordings. Based on the results, we built a 2.2 × 2.2 × 2.2 meter coil frame with a set of 3 × 4 coils to generate a 3D magnetic field and compared the measured flux density with our simulation results. In agreement with simulation results, the system yields a highly uniform field enabling high-resolution recordings of eye movements.

Quantifying the vestibulo-ocular reflex with video-oculography: nature and frequency of artifacts

Video-oculography devices are now used to quantify the vestibulo-ocular reflex (VOR) at the bedside using the head impulse test (HIT). Little is known about the impact of disruptive phenomena (e.g. corrective saccades, nystagmus, fixation losses, eye-blink artifacts) on quantitative VOR assessment in acute vertigo. This study systematically characterized the frequency, nature, and impact of artifacts on HIT VOR measures. From a prospective study of 26 patients with acute vestibular syndrome (16 vestibular neuritis, 10 stroke), we classified findings using a structured coding manual. Of 1,358 individual HIT traces, 72% had abnormal disruptive saccades, 44% had at least one artifact, and 42% were uninterpretable. Physicians using quantitative recording devices to measure head impulse VOR responses for clinical diagnosis should be aware of the potential impact of disruptive eye movements and measurement artifacts.

Changes in lung parenchyma after acute respiratory distress syndrome (ARDS): assessment with high-resolution computed tomography

The aim of this study was to evaluate the appearance, extent, and distribution of parenchymal changes in the lung after acute respiratory distress syndrome (ARDS) as a function of disease severity and therapeutic procedures. High-resolution computed tomography (HRCT), clinical examination, and lung function tests were performed in 15 patients, 6-10 months after ARDS. The appearance and extent of parenchymal changes were compared with the severity of ARDS, as well as with clinical and therapeutic data. Lung parenchymal changes resembling those found in the presence of pulmonary fibrosis were observed in 13 of 15 patients (87%). The changes were significantly more frequent and more pronounced in the ventral than in the dorsal portions of the lung ( p<0.01). A significant correlation was observed between the extent of lung alterations and the severity of ARDS ( p<0.01), and the duration in which patients had received mechanical ventilation either with a peak inspiratory pressure greater than 30 mmHg ( p<0.05), or with more than 70% oxygen ( p<0.01). Acute respiratory distress syndrome frequently is followed by fibrotic changes in lung parenchyma. The predominantly ventral distribution of these changes indicates that they may be caused by the ventilation regimen and the oxygen therapy rather than by the ARDS.

[The value of sonography in the intensive care unit for the diagnosis of diaphragmatic paralysis]

PURPOSE

To assess the value of bedside sonography in the detection of diaphragmatic paralysis in patients in the intensive care unit.

METHODS

In this study, 100 patients who were admitted to the intensive care unit after thoracic operations were evaluated. Sonography of each hemidiaphragm was performed with coronal scans at the mid-axillary line on both sides with the patient supine. Absent and paradoxical diaphragmatic movement was considered to be indicative of diaphragmatic paralysis. All patients underwent additional fluoroscopy within 5 days.

RESULTS

In 13 patients (13%) sonography revealed diaphragmatic paralysis. All these results were confirmed with fluoroscopy resulting in a sensitivity and specificity for sonography of 100%.

CONCLUSION

Bedside sonography of the diaphragm at the intensive care unit is a reliable tool for diagnosing diaphragmatic paralysis.

MR imaging in children with nonperforated acute appendicitis: value of unenhanced MR imaging in sonographically selected cases

OBJECTIVE

The aim of this study was to describe the MR appearance of acute appendicitis and to determine the value of MR imaging for diagnosis of acute appendicitis.

SUBJECTS AND METHODS

Forty-five children (28 girls, 17 boys), 7-16 years old (mean age, 13 years old), with clinically diagnosed acute appendicitis underwent independently graded compression sonography by two radiologists. MR imaging was performed when sonography revealed acute appendicitis (observer 1, 16 [36%] patients; observer 2, 18 [40%] patients), was inconclusive (observer 1, two [4%] patients; observer 2, one [2%] patient), and was interpreted as normal (observer 1, two [4%] patients; observer 2, one [2%] patient) (n = 20). Axial T1-weighted turbo spin-echo sequences, T2-weighted turbo spin-echo sequences in the axial and coronal planes, and fat-suppressed short inversion time inversion recovery turbo spin-echo sequences in the axial plane (4-mm slice thickness) were obtained and evaluated independently by two radiologists. The ability to see acute appendicitis with MR imaging was evaluated, the appearance and morphologic changes were described, and the most accurate sequence was determined. All children in whom MR imaging was performed underwent surgery.

RESULTS

MR imaging revealed acute appendicitis in all cases (100%) by both observers. On T2-weighted ultra turbo spin-echo images, acute appendicitis appeared with a markedly hyperintense center, a slightly hyperintense thickened wall, and markedly hyperintense periappendiceal tissue. Unenhanced axial T2-weighted spin-echo imaging was the most sensitive sequence.

CONCLUSION

In this study group, MR imaging was a valuable technique for depiction of acute appendicitis.

Role of magnetic resonance imaging in renal transplant recipients with acquired cystic kidney disease

OBJECTIVES

To evaluate the impact of magnetic resonance imaging (MRI) in renal transplant recipients whose ultrasound (US) examinations of the native kidneys have met the criteria of acquired cystic kidney disease (ACKD).

METHODS

The US scans of 840 renal allograft recipients were prospectively studied. In addition, 46 of 169 patients diagnosed with ACKD by US scans underwent MR examination. MRI protocols included (a) T1 and T2-weighted fast spin echo imaging, (b) T2-weighted gradient echo imaging, and (c) gadolinium-enhanced T1-weighted imaging in 7 patients with evidence of complex cysts. In the case of complex lesions, both US and MRI follow-up examinations were performed between 6 and 12 months after the prior examination.

RESULTS

US examination showed ACKD in 169 of 840 patients. In addition, US revealed 8 patients with renal cell carcinomas (RCC). Of these 8 patients, 7 had evidence of ACKD. The median number of cysts depicted on US examination in native kidneys of renal transplant recipients was 3 (range 0 to 10) on both sides. MRI revealed significantly more and smaller cysts compared to US. The median number of cysts was seven on the left and nine on the right native kidneys, respectively. MRI revealed 18 complex lesions in 7 patients. Thirteen of 18 complex lesions were undetected by US.

CONCLUSIONS

MRI is superior to US in depiction of simple and complex lesions of native kidneys in renal allograft recipients. MRI exhibits no overestimation of the prevalence of ACKD on the basis of the US criteria already mentioned. Advantages of MRI do not justify routine screening tests by this imaging modality. However, MRI should be used for further evaluation of complex lesions detected by US.

[Prevalence of abdominal aortic aneurysms: a sonographic screening study]

PURPOSE

To determine the prevalence of abdominal aortic aneurysms (AAA) in males above 60 years of age.

METHODS

1043 males of 60 years of age or older underwent sonographic examinations of the abdominal aorta. All of the candidates had volunteered for the examination, and special care was taken to avoid preselection of the candidates. Wherever possible, information was obtained on the following risk factors: cholesterol level, nicotine, diabetes, insulin and other medication, hypertonia and cardiac risk.

RESULTS

An AAA was diagnosed in 2.59% of the cases, while ectasia of the abdominal aorta was detected in 11.89%. The mean diameter of the aneurysms was 39.1 mm. Significant correlations between the various risk factors and abnormalities of the abdominal aorta could be established in patients suffering from angina pectoris (p = 0.004) and from congestive heart failure (p = 0.014).

CONCLUSIONS

AAA in males above 60 occurs in 2,590 out of 100,000 cases. The most noteworthy risk factors in the development of AAA are cardiovascular disorders.

Distinction between hepatic focal nodular hyperplasia and malignant liver lesions using technetium-99m-galactosyl-neoglycoalbumin

Distinction between hepatic focal nodular hyperplasia (FNH) and malignant liver lesions is essential because of the different therapy strategies, since FNH can be managed conservatively. The aim of this study was to describe the imaging pattern of FNH using the hepatocyte receptor ligand 99mTc-galactosyl-neoglycoalbumin 99mTc-NGA) and to assess the value of this receptor imaging agent in the differentiation of FNH from malignant liver lesions.

METHODS

Twelve consecutive patients with histologically confirmed FNH were investigated. The FNH-lesions were asymptomatic and incidentally found by ultrasonography. Nine patients with histologically verified hepatocellular carcinomas and three patients with liver metastases spread from gastrointestinal adenocarcinomas served as controls.

RESULTS

All FNH lesions showed normal or even increased uptake of 99mTc-NGA. Whereas malignant liver lesion-to-normal liver ratios amounted to 0.4 +/- 0.2 (mean +/- s.d.), FNH lesion-to-normal liver ratios were 1.7 +/- 0.3 (mean +/- s.d.).

CONCLUSION

The receptor imaging agent 99mTc-NGA with concurrent use of SPECT is useful in the differential diagnosis of FNH and malignant hepatic tumors.

Reduction of adverse events in MRI of the breast by personal patient care

PURPOSE

To determine the difference in anxiety reactions in patients undergoing standard (non-breast) magnetic resonance imaging (MRI) compared to breast magnetic resonance imaging (MRM) and to evaluate the influence of patient information before the breast imaging examination on the rate of premature termination of the procedure.

MATERIALS AND METHODS

Over 2 years, 5837 non-breast and 336 breast magnetic resonance examinations were performed at our institution. One group of breast MRM patients (n = 144) received detailed information and a second group (n = 189) received only routine information before MRI. The rates of premature termination were recorded for all groups.

RESULTS

In 0.5% (27/5837) of patients undergoing standard MRI examinations the study had to be stopped prematurely. Of the breast MRM patients, those who had received only routine information had a significantly higher rate of premature termination when compared to the better-informed patients and those undergoing standard MRI (5.5%, 10/189, P= 0.01). A significantly lower rate of premature termination occurred in the better-informed breast group (0%, 0/144).

CONCLUSION

MRM is associated with an increase in patient anxiety and higher rates of incomplete examination than other MR procedures. We recommend careful patient preparation including detailed verbal information before MRM and support during the procedure to obtain optimal patient compliance.

Prognostic factors for swallowing rehabilitation following head and neck cancer surgery

Thirty-two head and neck surgical patients with prolonged moderate to severe aspiration were assessed with videoendoscopic and videofluoroscopic swallowing studies to reveal all components of dysphagia and aspiration. All patients received functional swallowing therapy, and 75% of the patients regained full oral intake diet. The duration of non-oral feeding varied widely. The outcome of swallowing rehabilitation (success or failure, duration of non-oral feeding) was statistically correlated with preoperative tumour stage, patients' age, therapy onset, severity of aspiration and the results of the videofluoroscopic measurements of oral and pharyngeal transit time, pharyngeal delay time, duration of laryngeal closure and cricopharyngeal opening, hyoid and laryngeal elevation, presence or absence of a stenosis at the pharyngoesophageal segment. The following factors proved to be statistically significant for the prognostic estimate of swallowing rehabilitation: preoperative tumour stage, therapy onset, and severity of aspiration. For postoperative swallow recovery, an early therapy onset after thorough diagnostics with videoendoscopic and videofluoroscopic swallowing studies is recommended. Videofluoroscopic measurements will yield some prognostic estimate of oropharyngeal dysphagia and aspiration. Videoendoscopy, by it's availability and immediacy, proved to be useful for monitoring the course of rehabilitation.

Vasoactive intestinal peptide and somatostatin receptor scintigraphy for differential diagnosis of hepatic carcinoid metastasis

We report a case of a hepatic carcinoid metastasis mimicking a hemangioma on ultrasound and on CT. Indium-111-DTPA-D-Phe-1-octreotide (111In-OCT) and 123I-vasoactive intestinal peptide (123I-VIP) receptor images suggested a carcinoid metastasis of the liver. The final diagnosis was established histopathologically. The differential diagnosis of liver lesions is discussed.

Diaphragmatic dysfunction after heart or lung transplantation

BACKGROUND

The aim of this study was to evaluate the incidence and outcome of diaphragmatic dysfunction in patients after heart or lung transplantation and to assess the value of bedside sonography for the detection of diaphragmatic dysfunction.

METHODS

We prospectively evaluated 33 heart transplant recipients and 27 lung transplant recipients by use of sonography of the diaphragm and fluoroscopy.

RESULTS

Diaphragmatic dysfunction, diagnosed with ultrasonography and confirmed with fluoroscopy, was present in four heart transplant recipients (12.1%) and two lung transplant recipients (7.4%) and such dysfunction led to a statistically significant higher incidence of pneumonia during hospitalization and a nonstatistically significant increased length of intubation compared with patients with normal diaphragmatic function.

CONCLUSION

Diaphragmatic dysfunction, which can be reliably diagnosed with bedside sonography, is common after heart and lung transplantation and seems to have a negative influence on patient recovery.

Intraoperative and early postoperative colour Doppler sonography after carotid artery reconstruction: follow-up of technical defects

We studied 50 patients with intraoperative colour-coded Doppler sonography (CCDS) after carotid artery reconstruction. Technical defects could be detected in 19 cases (38 %): residual plaques in 9, flaps in 8 and strictures in 2. In 9 cases (18 %) the carotid endarterectomy was revised. One residual plaque and one residual stricture caused thrombosis at the operative site a few hours postoperatively. One of the patients with residual plaques developed a high-grade stenosis within the follow-up period. Of the patients with residual plaques two had a medium-grade stenosis at follow-up. Six flaps decreased in size or disappeared within 1 week after operation. No patient with a flap developed a stenosis within the follow-up period. Our findings seem to indicate that correction of intimal flaps less than 10 mm in size is not necessary.

Coefficient of variation: a powerful Doppler ultrasonographic parameter for detection of renal artery stenosis

The aim of our study was to objectively compare the effectiveness of various Doppler parameters in the diagnosis of renal artery stenosis. In three sheep, variable degrees of renal artery stenosis were induced and renal segmental arteries were investigated using pulsed Doppler sonography. In each animal the standard deviation of the instantaneous peak velocity within one cardiac cycle normalized by the mean peak velocity (coefficient of variation) had significantly higher normalized regression coefficients (k* = -0.215, average of three animals) when compared to resistive index (k* = -0.090) and acceleration index (k* = -0.069). In each individual animal, coefficient of variation detected lower pressure gradients (6.3 mm Hg, average value) than did resistive index (13.4 mm Hg) or acceleration index (17.3 mm Hg). The coefficient of variation may detect the presence of pressure gradients in renal artery stenosis more accurately than acceleration index or resistive index.

Use of resistance index for the diagnosis of breast tumours

AIM

To determine whether the resistance index (RI) contributes to the differential diagnosis of breast masses.

PATIENTS AND METHODS

In 56 breast tumours colour-coded Doppler sonography was performed and their resistance indices calculated from their spectral Doppler tracings. Histologic evaluation was obtained by excision biopsy.

RESULTS

In seven of 28 benign tumours (25%) no lesion was seen on ultrasound. In another seven benign tumours, no intratumoral vessels were demonstrated. The resistance index of the remaining 14 lesions (50%) varied between 0.5 and 0.75 with a mean value of 0.62 (standard deviation 0.08). Ultrasound missed one of 28 carcinomas (3.5%) and in one other tumour (3.5%) no flow was demonstrable. The resistance index of 26 malignant tumours varied between 0.56 and 0.9 with a mean value of 0.7 (standard deviation 0.08).

CONCLUSION

Breast malignancies have higher resistance indices with a wider range as assessed by colour-coded Doppler ultrasound (81% exceed 0.6) than do benign lesions. Due to the considerable overlap of the range of the resistance index, the measurements in any single patient may not be diagnostic. The absence of flow does not definitively exclude malignancy.

Globus sensation: value of static radiography combined with videofluoroscopy of the pharynx and oesophagus

Pharyngo-oesophageal abnormalities are found in a high proportion of patients with globus sensation. This study compares the diagnostic value of static single- and double-contrast radiography of the pharynx and oesophagus with videofluoroscopy and with videofluoroscopy combined with static radiography in these patients. Pharyngeal and oesophageal morphology and motor function were studied in 130 consecutive patients with globus sensation (46 males, 84 females; mean age, 47 years) by means of static single and double-contrast radiography and by videofluoroscopy. Videofluoroscopy revealed significantly more functional and structural abnormalities compared to static radiography. Pharyngeal and/or oesophageal disorders were found in 89 vs. 47 patients (chi2 [1] = 19.82, P = 0.0001), pharyngeal abnormalities in 54 vs. 27 patients (chi2 [1] = 13.5, P < 0.0002), and oesophageal abnormalities in 72 vs. 27 patients (chi2 [1] = 28.13, P < 0.0001). Videofluoroscopy combined with static radiography revealed significantly more abnormalities than videofluoroscopy alone (chi2 [1] = 4.23, P < 0.05), and assessed mucosal details more reliably than videofluoroscopy alone. The most frequent abnormalities found were nonspecific oesophageal motor disorders, pharyngo-oesophageal sphincter dysfunction, pharyngeal stasis, achalasia, and laryngeal penetration or aspiration of barium. In most patients with globus sensation, pharyngeal and/or oesophageal abnormalities can be detected radiographically. Videofluoroscopy revealed significantly more functional but not morphological abnormalities than did static radiography. Videofluoroscopic studies combined with static radiography had a higher diagnostic value than videofluoroscopic studies alone.

Intrarenal Doppler ultrasonography: which vessel should be investigated?

The aim of our study was to determine whether the site of intrarenal Doppler measurement influences diagnosis of renal artery stenosis. In an experimental test, three sheep with variable degrees of renal artery stenosis were investigated. In each animal, the resistive index from renal segmental arteries correlated better with mean pressure gradient (r = 0.85, 0.71, 0.85) and had lower standard deviation (s = 0.02 to 0.05) than resistive index from interlobar arteries (r = 0.48, 0.54, 0.61) (s = 0.03 to 0.11). In two animals the difference was significant (correlation: P < or = 0.01, P = 0.13, P < or = 0.05; standard deviation: P < or = 0.01, P < or = 0.34, P < or = 0.05). For detecting renal artery stenosis, vessels within the renal sinus should be used for Doppler sampling.

[Rate of thrombosis after cava filter implantation. Long-term results]

Thrombosis of the access site and occlusion of the inferior vena cava after placement of an inferior vena caval filter are known complications of caval interruption. 30 patients were evaluated with colour-coded Doppler sonography 4 to 66 months (average 2.5 years) after percutaneous placement of either a Günther filter, a Bird's Nest filter or a Simon-Nitinol filter. One right internal jugular vein had post-thrombotic alterations. One inferior vena cava was found to be occluded 15 months after Simon-Nitinol filter placement. The long-term occlusion rates of access site and inferior vena cava after percutaneous filter introduction are low. These two factors need not be considered if implantation of a caval filter is contemplated.

Ultrasound-guided supraclavicular approach for regional anesthesia of the brachial plexus

We prospectively studied 40 patients (ASA grades I-III) undergoing surgery of the forearm and hand, to investigate the use of ultrasonic cannula guidance for supraclavicular brachial plexus block and its effect on success rate and frequency of complications. Patients were randomized into Group S (supraclavicular paravascular approach; n = 20) and Group A (axillary approach; n = 20). Ultrasonographic study of the plexus sheath was done. After visualization of the anatomy, the plexus sheath was penetrated using a 24-gauge cannula. Plexus block was performed using 30 mL bupivacaine 0.5%. Onset of sensory and motor block of the radial, ulnar, and median nerves was recorded in 10-min intervals for 1 h. Satisfactory surgical anesthesia was attained in 95% of both groups. In Group A, 25% showed an incomplete sensory block of the musculocutaneous nerve, whereas all patients in Group S had a block of this nerve. Complete sensory block of the radial, median, and ulnar nerves was attained after an average of 40 min without a significant difference between the two groups. Because of the direct ultrasonic view of the cervical pleura, we had no cases of pneumothorax. An accidental puncture of subclavian or axillary vessels, as well as neurologic damage, was avoided in all cases. An ultrasonography-guided approach for supraclavicular block combines the safety of axillary block with the larger extent of block of the supraclavicular approach.

[Stenoses and occlusions of the abdominal aorta in patients less than 40-years old]

Stenosis or occlusion of the abdominal aorta in patients under 40 years of age is either due to a congenital malformation (abdominal aortic coarctation) or due to idiopathic aortitis (Takayasu's arteritis). Some authors, however, consider abdominal aortic coarctation as a subtype of Takayasu's arteritis. We evaluated 9 of our cases and 108 well-documented cases from the literature to help decide the question whether abdominal aortic coarctation is an entity of its own or a subtype of Takayasu's arteritis. In coarctation there is a slight male predominance, patients are usually younger than 20 years of age, and the short aortic stenosis is suprarenal with involvement of the renal arteries. In Takayasu's arteritis females are predominantly affected, patients are usually over 20 years of age, and the long aortic stenosis or occlusion is infrarenal without involvement of the renal arteries. Abdominal aortic coarctation must therefore be considered as a separate disease. Aortography is important, because the morphology of aortic alterations often allows a radiological diagnosis.

[Ultrasound-guided needle biopsies of thoracic space-occupying lesions]

This study is concerned with the results and experience gained from performing ultrasound-guided needle biopsies of thoracic masses in 56 patients. The accuracy of the biopsy results were related to the certainty of the method, the visibility of the biopsy needle on real time images, the effect of biopsy needle thickness and tumour size. Correct diagnosis was achieved in 84.6%. Inability to see the biopsy needle resulted in only 5.4% of cases and only when using a low frequency transducer (3 MHz). The thickness of the biopsy needle affected the accuracy of the biopsy, since all false negative or inconclusive biopsies resulted from the use of fine calibre needles. There was no significant correlation between tumour size and the accuracy of the biopsy results.

[The radiologic clinical picture of primary bone lymphoma]

Primary lymphoma of bone is a rare form of non-Hodgkin lymphoma which involves a single bone and has a relatively good prognosis following radiation therapy. We observed 17 histologically verified cases and found 97 cases in the literature. This rare tumour may occur at any time in adults and usually affects the metaphyses of long bones. It produces osteolytic changes and usually only mild periosteal reactions. Radiologically as well as histologically, differentiation from other highly malignant bone tumours is extremely difficult and sometimes impossible. A correct diagnosis can only be made from an accurate knowledge of the radiological appearances, localisation of the tumour and age of the patient.

[Aneurysms of the portal vein: an evaluation of 21 cases]

Reviewing 17 cases from the literature and 4 own cases we tried to throw light on the clinical and radiological appearance of the aneurysms of portal vein. The evaluation was performed in respect of sex, age, size, localisation and eventual combination with a portal hypertension. It appears that these aneurysms can be found at any age and that there is no sexual preference. In most cases these aneurysms are asymptomatic. In rare cases they may cause portal hypertension. This seems to be possible only with extrahepatic but not with intrahepatic location of the aneurysms.

[Percutaneous transluminal implantation of the Günther cava filter: experience based on 22 patients]

During the last three years, Günther cava filters were implanted in 20/22 patients. The indications for the procedure were single pulmonary emboli in 4, recurrent pulmonary emboli in 6 and pelvic vein thromboses with free thrombus but without pulmonary emboli in 12. In 2 patients implantation of the cava filter could not be carried out because of low position of the renal veins. 15 patients were re-examined 2 weeks to 20 months after the introduction of the filter. In no cases was there clinical evidence of recurrent pulmonary emboli. Occlusion of the inferior vena cava was demonstrated in 1 patient and downward displacement of the cava filter in 6 patients. Perforation of at least one prong of the filter through the wall of the inferior vena cava could be recognized in 4 patients. In 1 patient there was fracture of one leg of the filter but this was clinically not apparent.

Tumor vascularization: assessment with duplex sonography

In this prospective study, the authors examined 123 patients with benign or malignant neoplasms (breast cancer, n = 44; liver neoplasms, n = 43; and tumors affecting other organs, n = 36) to establish general criteria for evaluation of neoplastic lesions by means of duplex sonography. The frequency shifts determined by means of different Doppler frequencies (2.31 or 3.75 MHz) were converted into flow velocities. Only the highest systolic peak flow velocity obtained from a lesion was used for statistical evaluation. Receiver operating characteristic curves showed that a flow velocity of 0.4 m/sec is the optimal threshold value with which to differentiate benign from malignant tumors. The data obtained in all lesions indicated that only positive findings are potentially reliable. It is concluded that negative results of sonography should not be used to diagnose the presence of a benign lesion. The resistive index of the tumors was of negligible importance.

[Value of supine thoracic radiography in the diagnosis and quantification of pleural effusions: comparison with sonography]

The purpose of this prospective study was to verify the value of the supine chest radiograph with regard to the recognition and quantification of pleural effusions. The findings of supine chest radiographs were compared to those of chest sonography in a total of 320 pleural cavities. The correct identification and quantification of a pleural effusion was possible by supine chest radiograph alone in only 55% of cases (176/320). In 20% (64/320) supine chest x-ray was falsely negative and in 15% (48/320) falsely positive. In 10% an existing effusion was in fact recognised on supine chest x-ray; however the amount of effusion was wrongly estimated.

[The value of different clinical and imaging procedures for the postoperative follow-up of extra-anatomical bypasses]

In order to judge the patency of extra-anatomical by-passes in the lower extremities, 24 patients with 29 by-passes were examined clinically (palpation of the by-pass pulse, Fontaine staging, Doppler index) and by imaging methods (i-v DSA, Duplex sonography, colour-coded Doppler sonography). The value of these methods was compared. Sonography was found to be the ideal method for follow-up. Palpation was unreliable, particularly for femoro-femoral by-passes. The Doppler index and the Fontaine method provided no information about the actual state of the bypass. Angiography is indicated only if further vascular reconstruction is planned.