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Biomedical subjects

Dieter zur Nedden

Publications and source records attributed to Dieter zur Nedden.

At least 19 recordsLinked to original sources
PubMed2007

Value of contrast-enhanced ultrasound and elastography in imaging of prostate cancer.

PURPOSE OF REVIEW: Prostate cancer is the most commonly diagnosed malignancy in men. Gray-scale ultrasound-guided systematic biopsy is the standard of care for prostate cancer detection in men with an elevated prostate-specific antigen or an abnormal digital rectal examination. Systematic biopsy may miss up to 35% of clinically relevant cancers. Color and power Doppler ultrasound, ultrasound contrast agents, and elastography have and will dramatically change the role of ultrasound in prostate cancer diagnosis. RECENT FINDINGS: Several reports have demonstrated that contrast-enhanced ultrasound investigations of the blood flow of the prostate allow for prostate cancer visualization and therefore, for targeted biopsies. Comparisons between systematic and contrast-enhanced ultrasound-targeted biopsies have shown that the targeted approach detects more cancers with a lower number of biopsy cores. Furthermore, contrast-enhanced ultrasound has been shown to detect cancers with higher Gleason scores compared with the systematic approach, which seems to improve prostate cancer grading. In addition, elastography is a new ultrasound technique that allows for the assessment of tissue elasticity. SUMMARY: Contrast-enhanced ultrasound and elastography improve prostate cancer detection and may be useful for prostate cancer grading and staging. Future clinical trials will be needed to determine the promise of these new advances for ultrasound of the prostate evolving into clinical applications.

Humans↗
PubMed2006

Multislice computed tomography for detection of patients with aortic valve stenosis and quantification of severity.

OBJECTIVES: The purpose of this study was to evaluate whether multislice computed tomography (MSCT) provides a reliable, noninvasive imaging modality for identification of patients with degenerative aortic valve stenosis (AS) by quantifying the aortic valve area (AVA) in comparison to the accepted diagnostic standard transthoracic echocardiography (TTE). BACKGROUND: Management of patients with degenerative AS is based on the severity of disease. The severity of AS in clinical practice is assessed by TTE and classified as mild, moderate, or severe according to the AVA. METHODS: Forty-six patients were examined with contrast-enhanced, electrocardiogram-gated, 16-row MSCT for the evaluation of the diagnostic accuracy. In 30 patients, quantification of the AVA with MSCT was compared to TTE using the continuity equation with Doppler velocity-time integral for calculation of the AVA. RESULTS: Sensitivity of MSCT for the identification of patients with degenerative AS was 100%, and the specificity was 93.7%. Thirty of 46 patients had AS determined by TTE. Quantification of AVA by MSCT (mean AVA = 0.94 cm2) in patients with AS showed a good correlation to TTE (r = 0.89; p < 0.001). Bland-Altman plot illustrated good intermodality agreement between the two methods (limits of agreement, 0.20; 0.29). CONCLUSIONS: Multislice computed tomography may provide an accurate, noninvasive imaging technique for detection of patients with AS and quantification of AVA.

Aged↗
PubMed2006

Body size, body proportions, and mobility in the Tyrolean "Iceman".

Body mass and structural properties of the femoral and tibial midshafts of the "Iceman," a late Neolithic (5,200 BP) mummy found in the Tyrolean Alps, are determined from computed tomographic scans of his body, and compared with those of a sample of 139 males spanning the European early Upper Paleolithic through the Bronze Age. Two methods, based on femoral head breadth and estimated stature/bi-iliac (pelvic) breath, yield identical body-mass estimates of 61 kg for the Iceman. In combination with his estimated stature of 158 cm, this indicates a short but relatively wide or stocky body compared to our total sample. His femur is about average in strength compared to our late Neolithic (Eneolithic) males, but his tibia is well above average. His femur also shows adaptations for his relatively broad body (mediolateral strengthening), while his tibia shows adaptations for high mobility over rough terrain (anteroposterior strengthening). In many respects, his tibia more closely resembles those of European Mesolithic rather than Neolithic males, which may reflect a more mobile lifestyle than was characteristic of most Neolithic males, perhaps related to a pastoral subsistence strategy. There are indications that mobility in general declined between the European Mesolithic and late Neolithic, and that body size and shape may have become more variable throughout the continent following the Upper Paleolithic.

Adult↗
PubMed2006

Evaluation of ascending aortic atherosclerosis with 16-multidetector computed tomography is useful before total endoscopic coronary bypass surgery.

BACKGROUND: The purpose of this study was to investigate the assessment of ascending aortic atherosclerosis with 16-multidetector computed tomography (16-MDCT) angiography prior to total endoscopic coronary artery bypass (TECAB) surgery. METHODS: Forty-five patients were examined with electrocardiogram-gated, 16-MDCT angiography. The presence of atherosclerosis at the ascending aorta was graduated as severe (>50% of circumference) or as mild (<50% of circumference). Ascending aortic plaque composition was evaluated based on CT densities expressed as Hounsfield units (HU). TECABs using the Da Vinci telemanipulator were performed either on the arrested heart (n = 39) with an intra-aortic cardiopulmonary bypass (CPB) perfusion device or on the beating heart (n = 6) in patients with severe atherosclerosis. RESULTS: The presence of mild atherosclerosis at the ascending aorta (11/39) was associated with intra-aortic CPB perfusion device-related difficulties such as intra-aortic balloon migration (BM) or balloon rupture (P = .007) in arrested heart TECABs. The CT density of atherosclerotic plaque in patients with BM was mean 58 HU +/- 51 standard deviation (SD), suggesting noncalcifying plaque. In patients without BM, CT density of plaque was mean 526 HU +/- 306 SD corresponding to calcifying plaque (P < .001). Balloon rupture occurred in 2 patients who had calcifying plaque at the ascending aorta. CONCLUSION: Evaluation of ascending aortic atherosclerosis with 16-MDCT angiography is useful prior to TECAB surgery. Even mild atherosclerosis of the ascending aorta is associated with intraoperative difficulties regarding the remote-access perfusion system that is used for arrested heart TECAB surgery.

Aorta↗
PubMed2006

Aortic valve calcification as quantified with multislice computed tomography predicts short-term clinical outcome in patients with asymptomatic aortic stenosis.

BACKGROUND AND AIM OF THE STUDY: Aortic valve calcification may be an independent risk factor for adverse clinical outcome. The study aim was to assess the predictive value of possible risk factors, including the severity of aortic valve calcification as quantified with 16-multislice computed tomography (MSCT) for adverse short-term clinical outcome in patients with asymptomatic, degenerative aortic stenosis (AS). METHODS: Possible risk factors for adverse short-term clinical outcome were prospectively tested in 34 consecutive patients with asymptomatic AS as follows: (i) aortic valve calcium (AVC) score as quantified with MSCT; (ii) echocardiographic parameters--aortic valve area (AVA) calculated with continuity equation, mean and maximal transvalvular pressure gradients, end-diastolic septal wall diameter; and (iii) laboratory tests (brain natriuretic peptide (BNP), C-reactive protein (CRP)). RESULTS: Within 18-24 months of follow up, 11 of 34 patients developed a major adverse clinical outcome. Ten patients suffered from onset of symptoms accompanied by hemodynamic progression, and one patient died from sudden cardiac death. Six of these 10 patients underwent aortic valve replacement, one patient declined surgery, and three patients were not accepted for surgery (one of these died suddenly shortly afterwards). The aortic valve calcium score was the strongest predictor of a major adverse clinical event (p < 0.001) among all parameters assessed (1,928 +/- 789 versus 5,111 +/- 2,409 Agatston units). The plasma level of BNP (p = 0.003), mean transvalvular pressure gradient (p = 0.002) and AVA (p = 0.003) were also risk factors for adverse clinical outcome. CONCLUSION: The AVC score as quantified with MSCT predicted adverse short-term clinical outcome in patients with asymptomatic AS. In patients with severe aortic valve calcification, close follow up examinations are mandatory, and early elective surgery may be considered even in the absence of symptoms. MSCT provides a comprehensive non-invasive imaging approach for risk stratification in patients with asymptomatic AS.

Aortic Valve↗
PubMed2004

Power Doppler ultrasound imaging for quantification of urinary bladder neck blood flow changes.

This study was designed to evaluate power Doppler imaging for assessment of urinary bladder neck blood flow in comparison with laser Doppler flowmetry (LDF) in an animal model. Transrectal power Doppler ultrasound (US) and LDF of the urinary bladder neck were performed in three anesthetized pigs during comparative cystometry. Normal saline (NaCl) was used for the first run, followed by a second run with 0.2 mol/L potassium chloride (KCl). Standardized sonographic equipment settings (Acuson Sequoia 512); MountainView, CA) were used for power Doppler imaging. Computer-assisted calculation of color pixel density (CPD) of power Doppler images was performed using Scion Image) software image analysis. Tissue perfusion units (TPU) were measured using a BLF21 laser Doppler flowmeter (Transonic Systems Inc., Ithaca, NY, USA). The power Doppler results were compared with the findings obtained by LDF. NaCl filling resulted in a mean CPD increase at the bladder neck from 18.65 (+/- 1.78) at empty bladder to 37.8 (+/- 1.84) at 100 mL and to 88.32 (+/- 1.35) at full bladder capacity (C(max)) of 270 mL, respectively. With KCl filling, a mean CPD increase from 18.65 (+/- 1.78) to 59.63 (+/- 0.5) at 100 mL and 110.82 (+/- 2.98) at full bladder capacity (270 mL) was observed. The CPD increase was significantly higher for KCl than with NaCl (p < 0.001). With NaCl filling, bladder neck blood flow increased from 22 TPU (empty) to 46 TPU (100 mL) and 62.5 TPU at C(max), compared to 22 TPU, 50 TPU and 102.5 TPU with KCl. CPD and TPU measurements showed a strong correlation at p = 0.01. In conclusion, transrectal power Doppler US image quantification is a feasible and accurate method for assessing blood flow changes in the urinary bladder neck.

Animals↗
PubMed2004

Value of transducer positions in the measurement of finger flexor tendon thickness by sonography.

OBJECTIVE: To assess the value of 2 transducer positions for measurement of finger flexor tendon thickness by sonography. METHODS: Flexor tendon thickness of the third finger was measured sonographically by 2 independent investigators in 20 healthy volunteers (n = 40 fingers) and in 4 cadaveric specimens (n = 4 fingers). Flexor tendon thickness was measured at histologic examination in the cadaveric specimens. We defined the area of the A1 annular pulley as position I and the area of the A2 annular pulley as position II. Sonographic measurements were performed in transverse (dorsovolar and radioulnar) and longitudinal planes. Interobserver and intraobserver variabilities were evaluated by each investigator performing 3 measurements at each position. RESULTS: In position I, volunteers had flexor tendon thickness of 2.7 to 4.0 mm (mean +/- SD, 3.28 +/- 0.26 mm) longitudinally; transversally the thickness was 2.5 to 4.0 mm (mean, 3.34 +/- 0.29 mm) dorsovolar and 5.5 to 8.9 mm (mean, 7.34 +/- 0.71) radioulnar in position I. Position II revealed thickness of 3.2 to 4.2 mm (mean, 3.6 +/- 0.23 mm) longitudinally; transversally the thickness was 2.7 to 4.1 mm (mean, 3.4 +/- 0.27) dorsovolar and 4.3 to 6.8 mm (mean, 5.27 +/- 0.65) radioulnar. Interobserver and intraobserver variability for position I was better than for position II (P < .01 versus P < .05). Sonographic findings correlated excellently with histologic findings (r2 = 0.94). CONCLUSIONS: Standardized transducer positions for sonographic measurements of finger flexor tendon thickness showed good interobserver and intraobserver variability. Position I was found to be more reliable than position II.

Adult↗
PubMed2004

The influence of left renal vein entrapment on outcome after surgical varicocele repair: a color Doppler sonographic demonstration.

OBJECTIVE: To evaluate the impact of left renal vein entrapment on outcome after surgical varicocele repair using color Doppler sonography. METHODS: Eighty-four men had varicoceles on color Doppler sonography (2 right sided, 74 left sided, and 8 bilateral), which were diagnosed on the basis of a venous diameter of 3 mm or greater and venous retrograde flow in the pampiniform plexus of veins during the Valsalva maneuver or when changing from a supine to an upright position. Diagnosis of the left renal vein entrapment was based on the following criteria: antero-posterior diameter of greater than 1 cm and peak velocity of less than 15 cm/s for the left renal vein at the mid portion and anteroposterior diameter of less than 0.2 cm and peak velocity of greater than 110 cm/s (or, alternatively, a diameter ratio and peak velocity ratio of >5) for the left renal vein between the aorta and superior mesenteric artery. All patients underwent surgical varicocele repair. In postoperative follow-up, we compared the presence of left renal vein entrapment with the frequency of varicocele recurrence. RESULTS: Sixteen (19%) of 84 patients had left renal vein entrapment with a left-sided varicocele. Postoperatively (mean follow-up +/- SD, 19.3 +/- 11.7 months), 27 (32.2%) of 84 had varicocele recurrence, including all 16 patients with left renal vein entrapment and 11 (20.1%) of 68 patients without left renal vein entrapment. The varicocele recurrence rate was significantly greater in patients with left renal vein entrapment (P < .001, Fisher exact test). CONCLUSIONS: The presence of left renal vein entrapment resulted in a significantly higher varicocele recurrence rate. Patients with varicoceles should routinely be evaluated for the presence of left renal vein entrapment before surgical repair.

Adult↗
PubMed2004

Age-related rhabdosphincter function in female urinary stress incontinence: assessment of intraurethral sonography.

OBJECTIVE: To assess dynamic intraurethral sonography in the diagnostic evaluation of the function of the rhabdosphincter in female patients with urinary stress incontinence in relation to patient age. METHODS: Sixty-two patients with clinically proved urinary stress incontinence were investigated by means of intraurethral sonography with a 12.5-MHz endoluminal 9F catheter. The omega-shaped rhabdosphincter was visualized at rest and during voluntary contractions. Changes of muscle thickness and transducer-sphincter distance were measured and considered as parameters of muscle function. The intraurethral sonographic data were compared with results of standard urodynamic tests. RESULTS: Transducer-sphincter distance and sphincter muscle thickness showed a significant decrease with positive linear dependency on patient age (P < .001). Patients with grade III urinary stress incontinence had complete loss of sphincter contractility. A negative correlation was revealed between urethral closure pressure and patient age. CONCLUSIONS: We found an age-related decrease in rhabdosphincter function. Our results suggest that the rhabdosphincter is a substantial component of the continence mechanism in female urinary stress incontinence. Unlike urethral pressure profiles, which can only reveal zones of higher intraluminal pressure, transurethral sonography is highly specific for measurement of the function of the rhabdosphincter.

Adult↗
PubMed2004

Matching lung volume data sets--a novel approach.

There is a significant demand in matching CT datasets of the lung. The increasing number of CT slices per examination due to the higher resolution of modern CT scanners and the need for quantification of the progress of disease and healing processes in follow-up studies. A volunteer's lung was scanned by the means of multidetector CT in two different states of ventilation. The necessary lung structures for the matching procedure like lung surface and branching points were segmented. A thin-plate spline method was used to calculate the matched lung volume. The preliminary results show an average error of 2 voxel, i.e. 2mm. The calculation of the transformation matrix takes about one second on a conventional PC, which is considerably faster than other methods described in literature. The method described may be apt to be introduced in radiological practice when it comes to compare high resolution CT scans in follow-up studies quantitatively.

Animals↗
PubMed2003

Ovoid shape of the vermiform appendix: a criterion to exclude acute appendicitis--evaluation with US.

PURPOSE: To investigate whether the shape of the appendix in transverse section may be considered an ultrasonographic (US) criterion to exclude or confirm acute appendicitis. MATERIALS AND METHODS: The shapes of appendices of 100 control subjects, of 174 patients with clinical suspicion of acute appendicitis but without acute appendicitis, and of 108 patients with acute appendicitis were prospectively evaluated with US. Definite diagnoses in patients with clinical suspicion of acute appendicitis were established and confirmed either with surgery and histologic examination in 161 patients or with clinical follow-up in 121 patients. Statistical measures such as sensitivity, specificity, positive and negative predictive values, and accuracy were assessed for the appendiceal shape as a diagnostic US criterion for acute appendicitis. RESULTS: An at least partly round appendix indicated acute appendicitis with a sensitivity of 100%; specificity of 37%; positive and negative predictive values of 50% and 100%, respectively; and accuracy of 61%. In 67 of 174 patients with clinical suspicion of acute appendicitis but without acute appendicitis, the partly ovoid appendiceal shape aided in the exclusion of acute appendicitis, since it indicated a normal appendix with a probability of 86%. In 65 of 174 patients with clinical suspicion of acute appendicitis but without acute appendicitis, the ovoid shape over the entire appendiceal length excluded acute appendicitis with confidence. CONCLUSION: The shape of the appendix in transverse section is a useful US criterion, since an ovoid shape over the entire appendiceal length reliably rules out acute appendicitis.

Acute Disease↗
PubMed2003

Paranasal and orbital anatomy revisited: identification of the ethmoid arteries on coronal CT scans.

OBJECTIVE: The aim of this study was to identify recognizable landmarks on coronal CT (CCT) scans for the localization of the anterior and posterior ethmoid arteries, which are important anatomic structures and surgical landmarks within the ethmoid sinuses. MATERIALS AND METHODS: Four series of plastinated cadaver specimens and 80 CCT examinations were evaluated to identify the anatomical landmarks that define the course of the anterior and posterior ethmoid arteries within the ethmoid sinuses. RESULTS: The following anatomic landmarks: the indentations into the medial orbital wall, the relationship between the superior oblique and medial rectus orbital muscles, and the lateral ethmoid fovea wall thinning proved to be useful CCT landmarks for the localization of the anterior and posterior ethmoid arteries. CONCLUSION: The results of this study suggest that familiarity with the above-mentioned landmarks on routine CCT images facilitates the localization of the anterior and posterior ethmoid arteries as they enter the ethmoid sinus.

Adolescent↗
PubMed2002

Schwannoma of the brachial plexus: cross-sectional imaging diagnosis using CT, sonography, and MR imaging.

Primary brachial plexus tumors are rare, usually benign, and in general have a good prognosis after surgical excision. We present a case of a schwannoma in which sonography enabled the correct diagnosis of a probably benign brachial plexus tumor. Key to the diagnosis was the demonstration of a smooth-bordered, longish, and well-defined nodule along a brachial plexus nerve root. Cross-sectional imaging modalities that provide a high degree of soft tissue contrast and spatial resolution, such as sonography and MR imaging, were suitable methods to establish the correct preoperative diagnosis. Findings at CT, sonography, MR imaging, and surgery are discussed.

Adult↗
PubMed2002

Laparoscopic pyeloplasty for UPJ obstruction with crossing vessels: contrast-enhanced color Doppler findings and long-term outcome.

OBJECTIVES: To evaluate, in the present long-term follow-up study, contrast-enhanced color Doppler imaging (CDI) findings and the clinical outcome of patients with crossing vessels at the obstructed ureteropelvic junction (UPJ), who underwent laparoscopic pyeloplasty. In a previous study, contrast-enhanced CDI proved capable of detecting crossing vessels at the UPJ. METHODS: A total of 23 patients, who had undergone laparoscopic pyeloplasty and displacement of crossing vessels for UPJ obstruction at least 2 years before this study (mean 27 months), underwent contrast-enhanced CDI, intravenous urography, and renography. Contrast-enhanced CDI was performed using intravenously administered Levovist to assess the displacement of the vessels relative to the UPJ. All patients completed analog follow-up pain scales and quality-of-life assessment questionnaires. RESULTS. Contrast-enhanced CDI revealed a cranial displacement (mean 1.3 cm) of the crossing vessels from the UPJ in all 23 cases. Intravenous urography showed a decrease in the degree of hydronephrosis, with a success rate of 100% in low-grade and 86% in high-grade hydronephrosis. The split renal function improved from 39.7% to 48.1%. Analog pain scale measurements demonstrated a mean improvement in pain of 92% (range 73% to 100%) and a mean quality-of-life score of 94 (range 78 to 100). CONCLUSIONS: Our series of patients with crossing vessels at the UPJ treated by laparoscopic pyeloplasty showed an excellent long-term successful outcome. Contrast-enhanced CDI allows for preoperative detection, as well as postoperative assessment, of the displacement of the crossing vessel. We recommend that the presence of a crossing vessel be routinely determined preoperatively, because it may influence the choice of treatment modality and thereby the clinical outcome.

Adolescent↗