J Rademaker

Humboldt-Universität zu Berlin, Berlín, Berlin, Germany

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Publications (27)50.94 Total impact

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    ABSTRACT: To evaluate the safety and the long-term clinical and hemodynamic results of primary stent placement of atherosclerotic calcified stenosis of the infrarenal aorta. Between July 1996 and July 1999, 15 patients (nine male, si- female; mean age, 53.9 years) with symptomatic, calcified aortic stenosis were treated with primary stent placement. Patients underwent abdominal aortography and bilateral lower extremity arteriography. Follow-up was performed in all 15 patients. Technical success was defined as residual stenosis of less than 30% or a resting trans-systolic pressure gradient of less than 10 mm Hg after stent placement. Clinical patency was defined as the absence or improvement of symptoms after stent placement. Hemodynamic patency was defined as a normal triphasic Doppler waveform in the common femoral artery, an ankle-brachial index greater than 0.90, or the absence of a thigh-brachial pressure gradient at rest in either limb. Technical success was achieved in 13 of 15 patients. The two patients considered to be technical failures had resting trans-systolic pressure gradients of 12 and 13 mm Hg, respectively, after stent placement. After the mean follow-up of 36 months, primary clinical and hemodynamic patency rates were 85% and the secondary hemodynamic patency rate was 100%. Two of five symptomatic recurrences during the 36-month follow-up period (range, 12-46 months) were a result of aortic restenosis and were treated with repeated percutaneous transluminal angioplasty. None of the patients required aortic surgery. Complications of the primary procedure included one puncture site infection, one pseudoaneurysm, and one distal embolization, which delayed discharge of three patients. There was no morbidity during the secondary interventions. Primary stent placement as treatment of calcified infrarenal aortic stenosis proved to be safe and also provided durable long-term clinical improvement.
    No preview · Article · May 2004 · Journal of Vascular and Interventional Radiology
  • C Wissgott · D Scheinert · J Rademaker · M Werk · H Schedel · H J Steinkamp
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    ABSTRACT: To evaluate clinical and hemodynamical long-term results after laser angioplasty of long occlusions of the superficial femoral artery (SFA). In a prospective trial of 452 patients with long occlusions of the SFA, excimer percutaneous transluminal laser angioplasty (PTLA) for recanalization was applied. The average occlusion length of the SFA was 25.5 cm (range 16-38 cm). The recanalization attempt was done with the crossover technique in 398 patients, in 36 patients with the antegrade technique and in another 18 patients with the transpopliteal technique. The application of laser angioplasty demonstrated a successful recanalization of the SFA in 386/452 patients (85.5%). Recanalization with PTLA was not possible in 66 patients (14.5%). The main reason for the unsuccessful PTLAs was obstructing calcified material (n = 28) resistant to PTLA application. After a follow-up period of 48 months there was a primary, primary-assisted, and secondary patency rate of 22.3%, 40.9%, and 43.2%, respectively. Laser angioplasty of long occlusions of the SFA is a feasible procedure with a low failure rate. Long-term results are promising, but additional interventions are required in most patients if a patency rate of 43.2% is to be achieved after 4 years.
    No preview · Article · Mar 2004 · Acta Radiologica
  • H J Steinkamp · A Beck · M Werk · J Rademaker · R Felix
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    ABSTRACT: Assessment of the value of ultrasound examination in the determination of extracapsular neoplastic infiltration and soft tissue infiltration of cervical lymph nodes. In a prospective study the results of ultrasound studies in 110 patients with squamous cell carcinoma in the head-neck region were compared with the findings of the histologic examination after neck dissection. Ultrasound examination showed a specificity of 81.8 % in the determination of extracapsular neoplastic infiltration. The sensitivity was only 78.6 % - this was mainly caused by microscopic extracapsular growth, which gave false-negative results. Infiltration of blood vessels were identified in all patients. There was only one false negative diagnosis of muscle infiltration. The specificity (81.8 %) and sensitivity (78.6 %) of ultrasound examinations in the diagnosis of extracapsular infiltration in patients with lymph nodes metastasis is promising. But the examiner has to keep in mind that especially microscopic extracapsular neoplastic infiltration cannot be seen in ultrasound.
    No preview · Article · Nov 2003 · Ultraschall in der Medizin
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    ABSTRACT: The purpose of this article is to demonstrate the diagnostic impact of ultrasound in differentiating focal breast lesions with special regard on power Doppler and US contrast agents. The sonographic evaluation of breast lesions has become a standard procedure during the past 15 years. Especially the improvement of B-mode resolution and the use of high-frequency probes increased the diagnostic value of US. Assuming that the neoangiogenetic vascular architecture of solid breast lesions can be depicted reliably by color Doppler, many authors tried to differentiate between benignity and malignancy using Doppler criteria such as flow and morphologic aspects. Additionally, adjuvant techniques, such as harmonic imaging and new US contrast agents, are meant to be success-promising tools. Whereas the sensitivity and specificity of color Doppler have varied in different studies, prognostic prediction and treatment monitoring seem to be the future areas of application. To evaluate sufficiently flow signals of very small vessels with low flow velocity, the use of contrast-enhancing agents may be necessary. Nevertheless, an indispensable condition for successful Doppler-based assessment of the entity of breast lesions is the standardization of techniques, evaluation, analysis and weighting of the parameters.
    No preview · Article · Feb 2003 · European Radiology
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    ABSTRACT: To compare the immediate results, complication rates, and long-term outcomes of percutaneous transluminal laser angioplasty (PTLA) versus balloon dilation alone in the treatment of popliteal artery occlusions. In a prospective nonrandomized study conducted between December 1994 and June 2000, 215 symptomatic patients with unilateral popliteal occlusions were treated with either dilation alone (88 patients: 52 men; mean age 62 years, range 48-83) or PTLA (127 patients: 70 men; mean age 64 years, range 49-86) using a 308-nm excimer laser followed by dilation. The average occlusion length was 10.4 cm (range 3-14). PTLA was successful in recanalizing 105 (82.7%) arteries, while the recanalization rate for dilation alone was only 70.4% (62/88; p=0.045). After a mean follow-up of 36 months (range 6-52), the primary and secondary patency rates were 21.7% and 50.8%, respectively, in patients with PTLA and 16.3% and 35.2% in the angioplasty group (p=0.762). The complication rates associated with both techniques were similar. Although initial recanalization may be better with PTLA, it does not appear to add any long-term benefit over balloon dilation alone.
    No preview · Article · Jan 2003 · Journal of Endovascular Therapy
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    ABSTRACT: To compare the ability of standard power Doppler and color harmonic imaging for visualising breast tumor vascularity using ultrasound probes of various frequencies, and to evaluate the influence on diagnostic accuracy using ultrasound contrast agent. Twenty patients (x = 43.6 +/- 11.7 years) with suspected malignancy of the breast underwent power Doppler to evaluate vascularity and to offer a differential diagnosis of the lesion. Two criteria were used for differential diagnosis: The quantitative extent of vascularity ("percentage vessel area", PVA) and the qualitative assessment of vascular architecture. The following power Doppler modes were compared in every patient: Plain and enhanced (Levovist(R)) 9 MHz and 12 MHz standard power mode and enhanced 9 MHz color harmonic imaging-(CHI). The PVA increased from a mean of 2.2 +/- 2.9 % (9 MHz standard plain) via 4.8 +/- 4.1 % (12 MHz standard plain), 9.7 +/- 15.3 % (9 MHz standard enhanced), 17.4 +/- 20.0 % (9 MHz CHI enhanced) up to 19.4 +/- 14.8 % (12 MHz standard enhanced). The perceptibility of the vascular structure was best using the enhanced 12 MHz standard power mode, immediately followed by the enhanced 9 MHz CHI mode. The improved detection of vascular signal did not translate into improved diagnostic accuracy. The highest diagnostic accuracy (95 %) was obtained using the enhanced 9 MHz CHI mode (criterion "PVA") and the enhanced 9 MHz standard power mode (criterion "vascular structure"), whereas the 12 MHz probes delivered insufficient diagnostic accuracy and very low specificity. Best quantitative and qualitative visualisation of the tumor vascularity was achieved using the enhanced 12 MHz standard power mode. Nevertheless, the highest diagnostic accuracy was obtained using enhanced 9 MHz standard power Doppler and enhanced 9 MHz color harmonic imaging. The visualisation of tumor vascularity and, partially, the diagnostic accuracy are improved significantly by color harmonic imaging without changing the probe frequently.
    No preview · Article · Oct 2002 · RöFo - Fortschritte auf dem Gebiet der R
  • R.-J. Schröder · B. Rost · N. Hidajat · J. Rademaker · R. Felix · J. Mäurer

    No preview · Article · Sep 2002
  • R-J Schröder · B Rost · N Hidajat · J Rademaker · R Felix · J Mäurer
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    ABSTRACT: To compare the value of B-mode-, plain and contrast enhanced color Doppler ultrasound, CT and MRI with respect to their diagnostic accuracy in palpable enlarged cervical lymph nodes. Thirty patients (18 - 90 years old) with palpable enlarged lymph nodes of the head and neck underwent B-mode-ultrasound, plain and contrast enhanced color Doppler, CT and MRI (gold standard: histologic analysis in 22 and clinical follow up for at least six months in eight patients). The criteria of malignancy were maximal and minimal lymph node diameter, M/Q-ratio, various morphologic criteria (necrosis, hilus line, internal structure, contour, contrast enhancement), spectral Doppler indices, and vascular architecture in color Doppler. The highest sensitivity (= 1.00, specificity = 0.07 - 0.15) was obtained measuring the lymph node diameter independent on the used imaging modality (ultrasound, CT, MRI), the highest specificity (= 1.00, sensitivity = 0.71) analyzing the vascularity of the lymph node by plain color Doppler. The highest diagnostic (= 0.93) accuracy was delivered by contrast enhanced color Doppler analysis of the vascularity. Sensitivity (= 0.94) and specificity (= 0.92) of this imaging modality were only slightly inferior to the top values. Fisher's exact test revealed significant values in differentiating malignant from benign lymph nodes for B-mode- and MR-analysis of the M/Q-ratio (p < 0001/p < 0.05), B-mode morphology (p < 0.00005), plain and contrast enhanced color Doppler analysis of the vascularity (p < 0.0001/p < 0.000005), MR-morphology (p < 0.0001), and CT-morphology (p < 0.005). CT is inferior to MRI, B-mode-ultrasound and contrast-enhanced color Doppler in the differential diagnosis of selectively analyzed, palpably enlarged cervical lymph nodes using the criteria of our study. The analysis of the MR-morphology revealed a slightly inferior diagnostic accuracy to B-mode morphology and color Doppler analysis of the vascularity.
    No preview · Article · Sep 2002 · RöFo - Fortschritte auf dem Gebiet der R

  • No preview · Article · Sep 2002
  • H J Steinkamp · C Wissgott · J Rademaker · R Felix
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    ABSTRACT: The use of Power Doppler sonography in nodal diseases provides an improvement of early and noninvasive diagnosis of regional metastatic involvement. By using Power Doppler sonography it is possible to characterize lymph nodes as reactively enlarged, metastases, malignant lymphoma, tuberculosis and to study cervical cysts. The high diagnostic accuracy is based on perfusion-characteristics of these lymph nodes. Reactive lymph nodes show increased central perfusion of the hilum, whereas metastases tend to show increased peripheral perfusion. Affected lymph nodes in patients with by malignant lymphoma are highly perfused in the center but also peripheral. Power Doppler sonography is still not able to discriminate small (<8 mm) nonnecrotic metastasis or micrometastases from reactive lymph nodes. The purpose of this paper is to provide a summary of the current status of power Doppler and Doppler sonography in the differential diagnosis of lymph nodes.
    No preview · Article · Jul 2002 · European Radiology
  • H. Steinkamp · C. Wissgott · J. Rademaker · R. Felix
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    ABSTRACT: The use of Power Doppler sonography in nodal diseases provides an improvement of early and noninvasive diagnosis of regional metastatic involvement. By using Power Doppler sonography it is possible to characterize lymph nodes as reactively enlarged, metastases, malignant lymphoma, tuberculosis and to study cervical cysts. The high diagnostic accuracy is based on perfusion–characteristics of these lymph nodes. Reactive lymph nodes show increased central perfusion of the hilum, whereas metastases tend to show increased peripheral perfusion. Affected lymph nodes in patients with by malignant lymphoma are highly perfused in the center but also peripheral. Power Doppler sonography is still not able to discriminate small (<8mm) nonnecrotic metastasis or micrometastases from reactive lymph nodes. The purpose of this paper is to provide a summary of the current status of power Doppler and Doppler sonography in the differential diagnosis of lymph nodes.
    No preview · Article · Jun 2002 · European Radiology
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    ABSTRACT: To evaluate the safety and long-term results after laser angioplasty of short occlusions of the superficial femoral artery (SFA). In a prospective trial in 312 patients with short occlusions of the SFA excimer laser angioplasty for recanalization was applied. The average occlusion length of the SFA was 7.5 cm (range 1-10 cm). The recanalization attempt was done using either a cross-over technique from the contralateral femoral artery (278 patients), antegrade technique (16 patients) or transpopliteal technique (18 patients). Percutaneous transluminal laser angioplasty (PTLA) produced successful recanalization of the SFA in 286 of 312 patients (91.7%). In 26 patients (8.3%) recanalization was not possible. The reason for the unsuccessful PTLAs was obstructing calcified materialn = 8) which was resistant to laser application. In nine cases obstructing calcifications resulted in positioning of the laser catheter in subintimal tissue or perforation of the SFA. In another four patients there was an aberrant anatomy of the SFA which resulted in a direct vessel injury after advancing the laser catheter. In five patients subintimal recanalization failed. After a follow-up period of 36 months there was a primary, primary assisted and secondary patency rate of 49.2%, 76.5% and 86.3%. Excimer laser angioplasty of short occlusions of the SFA is a feasible procedure with a low failure rate. Long-term results are promising but additional interventions are required in most patients to achieve a patency rate of 86.3% after 3 years. Further studies are needed to compare the clinical outcome of PTLA and PTA in short occlusions of the SFA.
    No preview · Article · Jan 2002 · CardioVascular and Interventional Radiology
  • C Born · J Rademaker · N Hosten · R Felix
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    ABSTRACT: MRI is a useful tool to study space-occupying lesions of the orbit. We present two cases of intraorbital lesions that were found to be a hemorrhagic cavernous hemangioma and a ruptured dermoid, respectively. The difficulties in arriving at the diagnosis of these rare entities with MRI are discussed. In general, dermoids are characterized by a peripheral, extra-conal location in the immediate vicinity of an orbital suture, while cavernous hemangiomas tend to be intraconal. Secondary complications of both entities, such as hemorrhage or rupture, may alter the characteristic MRI signal patterns found in uncomplicated lesions. Inflammatory reactions may be observed. The signal of the fatty dermoid and the hemorrhagic part of a cavernoma are both of high intensity on the T1-weighted images, and this may lead to diagnostic difficulties.
    No preview · Article · Dec 2001 · Orbit (Amsterdam, Netherlands)
  • J Rademaker · V Griesshaber · N Hidajat · J W Oestmann · R Felix
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    ABSTRACT: A major concern about combined pulmonary CT angiography (PCTA) and CT venography (CTV) refers to the additional radiation exposure to the patient. The purpose of this paper is to analyze the organ dose, the effective dose, and the gonadal dose of combined PCTA and CTV. Effective dose and gonadal dose in PCTA and CTV were calculated. Also measured was the organ doses with thermoluminescence dosimeters in six patients who underwent combined PCTA/CTV. The risk from the effective dose and gonadal dose in combined PCTA/CTV is low. Nevertheless, additional CTV increases the gonadal dose by a significant factor and use of this procedure should be limited in younger patients.
    No preview · Article · Nov 2001 · Journal of Thoracic Imaging
  • Z. S. Rosenberg · J. Rademaker · S. Grijseels · D. Feldman
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    ABSTRACT: Purpose: (1) To determine the accuracy of interpretation of plain radiographs by orthopedic residents in a minor trauma emergency room, (2) to evaluate the clinical significance of misinterpretations for patient management, and (3) to evaluate the necessity of routine plain film review by a radiologist and an efficient patient recall system. Materials and methods: Our retrospective study evaluated discrepancies in plain film reading between orthopedic residents and radiologists. A total of 2283 radiographic examinations were evaluated for discrepancies. The medical records and X-rays in misinterpreted cases were assessed by a musculoskeletal radiologist and a staff orthopedist. The misinterpretations were categorized based on their clinical significance and influence on medical care. Misinterpretations which required immediate change in treatment or mandated further work-up were considered to have high clinical significance. Results: Forty-six (2 %) of the 2283 interpretations were defined as misinterpretations. Of the 46 cases, 27 (59 %) were missed fractures, 5 (11 %) were missed tumors, and 7 (15 %) were false positive readings of normal films. Twenty-one (46 %) of the misinterpretations had significant consequences. Forty-one percent of missed fractures had a high clinical significance, whereas only 14 % of false positive readings had a high clinical significance. Conclusion: The accuracy of plain film interpretation by orthopedic residents in the minor trauma setting is high (98 %). Nevertheless, 46 % of the misinterpretations have significant clinical consequences. This indicates that all emergency trauma films should be reviewed by an experienced radiologist, and an expedient method of informing the orthopedic department of any discrepancies in reading is recommended.
    No preview · Article · Jul 2001 · Emergency Radiology
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    ABSTRACT: Injuries of the peroneus tendons are common and both the athlete and the older population are at risk. MR imaging is a useful technique for revealing injuries of the peroneus tendons as well as showing anatomic factors associated with these lesions. This article reviews clinical factors and MR imaging characteristics of injuries of the peroneus tendons.
    No preview · Article · Feb 2001 · Rontgenpraxis
  • J. Rademaker · C. Born · R. Schröder · J. Ricke
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    ABSTRACT: Patients with the acquired immunodeficiency syndrome (AIDS) can develop a wide spectrum of diseases. AIDS-related diseases include opportunistic infections, AIDS-associated malignancies and complications from medications used to treat complications of AIDS. Ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) play an important role in the characterization, diagnosis and follow-up of patients with human immunodeficiency syndrome. While the presence of thoracic infections can best be diagnosed by using conventional chest films and CT, the assessment of cerebral complications is best achieved using MRI. The work-up of patients with abdominal symptoms should include ultrasound and CT. The use of the different radiographic methods for the detection of the numerous forms of infections and malignancies in AIDS patients is described in detail.
    No preview · Article · Jan 2001 · Tagliche Praxis
  • J. Rademaker · C. Born · R. Schröder · J. Ricke
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    ABSTRACT: Patients with the acquired immuno-deficiency syndrome (AIDS) can develop a wide spectrum of diseases. AIDS-related diseases include opportunistic infections, AIDS-associated malignancies and complications from medications used to treat complications of AIDS. Ultrasound, computed tomography (CT) and magnetic resonance imaging (MRI) play an important role in the characterization, diagnosis and follow-up of patients with human immunodeficiency syndrome. While the presence of thoracic infections can best be diagnosed by using conventional chest films and CT, the assessment of cerebral complications is best achieved using MRI. The work-up of patients with abdominal symptoms should include ultrasound and CT. The use of the different radiographic methods for the detection of the numerous forms of infections and malignancies in AIDS patients is described in detail.
    No preview · Article · Jan 2001 · Internistische Praxis
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    ABSTRACT: To determine the magnetic resonance (MR) imaging features that characterize tear of the peroneus longus tendon at the midfoot. Medical records and MR images in nine patients with a tear of the middle segment of the peroneus longus tendon were retrospectively reviewed. All nine patients had undergone routine ankle MR imaging; three had undergone additional oblique coronal MR imaging. Surgical proof of a tear was available for three patients. Partial tear was present in four patients, and complete tear was present in five. Partial tears were characterized by heterogeneous signal intensity and thickening of the tendon. Complete tears were characterized by discontinuity of the tendon. Additional findings included fluid in the tendon sheath (n = 6), marrow edema of the lateral calcaneal wall (n = 3), enlarged peroneal tubercle (n = 3), and tear of the peroneus brevis tendon (n = 2). The extent of the tear was better assessed with oblique coronal MR images. The characteristic MR imaging appearance of complete or partial tear of the middle portion of the peroneus longus tendon includes foci of increased signal intensity in the distal tendon, morphologic alterations, and/or discontinuity of tendon. Bone marrow edema along the lateral calcaneal wall may be suggestive of the diagnosis. Additional oblique coronal midfoot MR images may help in assessment of the extent of the tear.
    No preview · Article · Apr 2000 · Radiology
  • A Argiris · J Rademaker · M Mahmud

    No preview · Article · Dec 1997 · Intensive Care Medicine

Publication Stats

433 Citations
50.94 Total Impact Points

Institutions

  • 2000-2004
    • Humboldt-Universität zu Berlin
      • Department of Biology
      Berlín, Berlin, Germany
  • 1996-1997
    • Beth Israel Medical Center
      • Department of Medicine
      New York City, New York, United States
  • 1993-1995
    • Universität zu Lübeck
      • Institut für Neuroradiologie
      Lübeck, Schleswig-Holstein, Germany