N F Schreiter

Publications (9)24.16 Total impact

• Article: Optical Imaging of Breast Cancer Using Hemodynamic Changes Induced by Valsalva Maneuver.

  N F Schreiter, N Volkwein, P Schneider, M H Maurer, S Piper, C Schmitz, A Poellinger
  [show abstract] [hide abstract]
  ABSTRACT: Purpose: To investigate whether changes in hemodynamics induced by Valsalva maneuver can be exploited for detecting and characterizing breast lesions by optical mammography. Materials and Methods: 30 women underwent optical imaging of the breast using a DYNOT 232 system and performing Valsalva maneuvers prior to biopsy. Changes in light absorption due to changes in oxyhemoglobin and deoxyhemoglobin concentrations were recorded volumetrically and in a time-resolved manner. The parameters full width at half maximum (FWHM), time to ten (TTT), and peak amplitude (PA) of the reconstructed concentration time curves yielded color-coded maps of the breast which were separately evaluated by two experienced readers for detection rate, degree of visibility, and detection of additional lesions. ROC analysis was performed with the evaluation results. Results: 10 patients were excluded from analysis due to artifacts or inadequately performed Valsalva maneuver. The resulting 20 patients showed a clear increase in oxygenated and deoxygenated hemoglobin concentration after the onset of the Valsalva maneuver. ROC analysis yielded AUC values (0.393 - 0.779) that did not differ from random probabilities. The highest AUC values were obtained for FWHM (AUC: 0.779, detection rates [60 - 70 %], identification of additional lesions [55 - 70 %]). PA analysis had the highest detection rate (70 - 90 %) but also the highest identification of false-positive additional lesions (80 - 90 %). The concordance rates of the two readers for malignant lesions were satisfactory (0.524 - 1.0). Conclusion: Our study revealed susceptibility to artifacts and a large number of false-positive additional lesions, suggesting that the evaluation of hemodynamic changes after Valsalva maneuver by optical imaging is not a promising method.
  RöFo - Fortschritte auf dem Gebiet der R 03/2013; · 2.76 Impact Factor
• Article: Midterm Results after Uterine Artery Embolization Versus MR-Guided High-Intensity Focused Ultrasound Treatment for Symptomatic Uterine Fibroids.

  V Froeling, K Meckelburg, C Scheurig-Muenkler, N F Schreiter, J Kamp, M H Maurer, A Beck, B Hamm, T J Kroencke
  [show abstract] [hide abstract]
  ABSTRACT: PURPOSE: To compare the rate of reintervention and midterm changes in symptom severity (SS) and Total health-related quality of life (HRQoL) scores after uterine artery embolization (UAE) and magnetic resonance-guided high-intensity focused ultrasound (MR-g HIFU) for symptomatic uterine fibroids. METHODS: Eighty women (median age 38.3 years), equally eligible for MR-g HIFU and UAE who underwent one of both treatments between 2002 and 2009 at our institution, were included. The primary end point of the study was defined as the rate of reintervention after both therapies. The secondary outcome was defined as changes in SS and Total HRQoL scores after treatment. SS and Total HRQoL scores before treatment and at midterm follow-up (median 13.3 months) were assessed by the uterine fibroid symptom and quality-of-life questionnaire (UFS-QoL) and compared. RESULTS: The rate of reintervention was significantly lower after UAE than after MR-g HIFU (p = 0.002). After both treatments, SS and Total HRQoL scores improved significantly from baseline to follow-up (UAE: p < 0.001, p < 0.001; MR-g HIFU: p = 0.002, p < 0.001). Total HRQoL scores were significantly higher after UAE than after MR-g HIFU (p = 0.032). Changes in the SS scores did not differ significantly for both treatments (p = 0.061). CONCLUSION: UAE and MR-g HIFU significantly improved the health-related quality of life of women with symptomatic uterine fibroids. After UAE, the change in Total HRQoL score improvement was significantly better, and a significantly lower rate of reintervention was observed.
  CardioVascular and Interventional Radiology 03/2013; · 2.09 Impact Factor
• Article: [In Process Citation].

  R Thiel, N F Schreiter, A Poellinger
  RöFo - Fortschritte auf dem Gebiet der R 10/2012; 184(10):931-3. · 2.76 Impact Factor
• Article: [Change in health-related quality of life and change in clinical symptoms after uterine artery embolization in patients with symptomatic adenomyosis uteri - evaluation using a standardized questionnaire].

  V Froeling, C Scheurig-Muenkler, I G Steffen, N F Schreiter, T J Kröncke
  [show abstract] [hide abstract]
  ABSTRACT: To evaluate the clinical response of uterine artery embolization (UAE) in women with symptomatic uterine adenomyosis by comparing health-related quality of life and symptom severity before and after UAE using a standardized questionnaire. This longitudinal study at two time points included 17 patients with a median age of 47.1 years with symptomatic uterine adenomyosis (n = 7 pure adenomyosis; n = 10 with concomitant fibroids). The diagnosis was based on clinical symptoms and magnetic resonance imaging (MRI) criteria. Data on health-related quality of life and severity of symptoms before and after UAE were obtained by the standardized "Uterine Fibroid Symptom and Quality of Life" (UFS-QOL) questionnaire and correlated in the following. Treatment failure was defined as the need for a second invasive procedure because of recurrent symptoms or persistent symptoms after UAE. The median interval between the evaluation of the UFS-QOL questionnaire before and after UAE was 46.0 months. 70.6 % (12/17; 95 % confidence interval 44.0 %  - 88.6 %) of the patients had therapy response with a significant improvement of health-related quality of life and clinical symptoms (p-value = 0.002). The therapy failure rate was 29.4 % (5/17; 95 % confidence interval 11.4 %  - 56.0 %). One patient underwent dilatation and curettage and four patients underwent hysterectomy because of therapy failure. UAE to treat symptomatic adenomyosis uteri can significantly improve the health-related quality of life and clinical symptoms. However, therapy failure is possible in up to one-third of patients.
  RöFo - Fortschritte auf dem Gebiet der R 01/2012; 184(1):48-52. · 2.76 Impact Factor
• Article: Fast 3D Near-infrared breast imaging using indocyanine green for detection and characterization of breast lesions.

  P Schneider, S Piper, C H Schmitz, N F Schreiter, N Volkwein, L Lüdemann, U Malzahn, A Poellinger
  [show abstract] [hide abstract]
  ABSTRACT: To evaluate fast 3D near-infrared breast imaging using the optical contrast agent indocyanine green (ICG) for the detection and characterization of breast lesions. 30 patients with suspicious breast lesions on mammography and/or ultrasound underwent fast 2 Hz 3D optical mammography before, during, and after administration of a 25 mg ICG bolus prior to needle biopsy. The bolus kinetics is analyzed using two perfusion parameters and a derived parameter: "peak amplitude" (PA), "time-to-peak" (TTP) and "peak-time grouped amplitude" (PTA). A receiver operating characteristic curve (ROC) analysis was performed to define a PTA cut-off for reader-independent differentiation of benign and malignant lesions. 8 patients had to be excluded from data analysis. Overall 14 breasts bearing a malignant lesion, 8 breasts bearing a benign lesion and 3 healthy breasts were analyzed. The cut-off-based PTA analysis allowed correct detection for 12 of 14 malignant lesions (tumor size: 8 - 80 mm; sensitivity = 85.7 %). Two malignant lesions were missed. In the benign study group only one fibroadenoma was detected (specificity = 87.5 %). The PTA values differed significantly between the benign group and the malignant group (Mann-Whitney U-test, p < 0.05). Breasts with malignant lesions showed higher peaks at early time-points in ICG perfusion. Early perfusion analysis of ICG-enhanced 3D fast optical mammography revealed different enhancement patterns for benign and malignant lesions. This approach might help with the detection of malignant breast lesions and the differentiation from benign lesions.
  RöFo - Fortschritte auf dem Gebiet der R 10/2011; 183(10):956-63. · 2.76 Impact Factor
• Article: Qualitative JPEG 2000 compression in digital mammography - evaluation using 480 mammograms of the CDMAM phantom.

  N F Schreiter, I G Steffen, J Miller, E Fallenberg, A Poellinger, U Bick, F Diekmann
  [show abstract] [hide abstract]
  ABSTRACT: The DICOM standard supports both quantitative and qualitative lossy compression of mammograms.The purpose of this study was to investigate qualitative JPEG 2000 lossy compression and how different factors such as object thickness, radiation dose, and lossy compression levels affect image quality. The CDMAM phantom Artinis 3.4 was radiographed with 4 different object thicknesses and 5 different doses. The images were compressed at 10 different compression levels. The image quality was assessed by the software interpolated IQFinv value. Lossy 90 resulted in 89 % data reduction, lossy 70 in 95 % data reduction and lossy 60 in 96 % data reduction. At higher compression levels (lossy 30), the resulting image quality ranged from 80 - 36 %, and at low compression levels (lossy 90), it ranged from 89 - 93 %. The object thickness was found to significantly interact with the compression level with regard to the resulting image quality: a higher object thickness resulted in increasingly poor image quality at increasing compression levels (p < 0.05). Higher qualitative JPEG 2000 compression levels contribute only little additional data reduction, while the resulting image quality cannot be reliably predicted. Factors affecting image quality such as radiation dose and object thickness should be taken into account when performing image compression. Large object thicknesses should be compressed with caution because the loss of image quality is greater when intelligent data compression algorithms are used.
  RöFo - Fortschritte auf dem Gebiet der R 07/2011; 183(7):650-7. · 2.76 Impact Factor
• Article: Plasma levels following application of paclitaxel-coated balloon catheters in patients with stenotic or occluded femoropopliteal arteries.

  P Freyhardt, T Zeller, T J Kröncke, U Schwarzwaelder, N F Schreiter, H Stiepani, S Sixt, A Rastan, M Werk
  [show abstract] [hide abstract]
  ABSTRACT: Paclitaxel-coated balloon catheters inhibit restenosis after coronary and peripheral angioplasty (PCI,PTA). The aim of this study was to investigate paclitaxel plasma levels and laboratory parameters following PTA with paclitaxel-coated balloons (PCB) in peripheral arteries. This single treatment arm, multicenter study included 14 patients with Rutherford stage 1 - 5 with occlusions of up to 5 cm or ≥ 70 % diameter stenosis of the superficial femoral or popliteal arteries (SFA, PA). PTA was performed using up to three PCB catheters. The paclitaxel plasma levels and safety laboratory parameters were determined by collecting blood samples pre-intervention, immediately post-intervention, at 0.5, 1, 2, 4, 8, 24 hours and 1 and 4 weeks post-intervention (p. i.). Vital signs were monitored to assess clinical safety. PTA was performed successfully in all patients. Paclitaxel plasma levels were always below a level and duration known to cause systemic side effects. A mean peak paclitaxel plasma level (40 ng/ml) was reached immediately p. i. and decreased rapidly below detectable levels in more than half of the patients already 2 hours p. i. The paclitaxel plasma concentrations returned to values below detectable levels at 24 hours p. i. in all patients. Laboratory parameters and vital signs did not give any reason for safety concerns. No adverse events associated with balloon coating were observed. The results of 14 patients with peripheral arterial occlusive disease show no systemic bioavailability of paclitaxel > 24 hours after PTA with one or more PCB catheters, indicating that the PCB catheter is safe with regard to possible systemic effects.
  RöFo - Fortschritte auf dem Gebiet der R 01/2011; 183(5):448-55. · 2.76 Impact Factor
• Article: [Targeted methods for measuring patient satisfaction in a radiological center].

  M H Maurer, E Stein, N F Schreiter, D M Renz, A Poellinger
  [show abstract] [hide abstract]
  ABSTRACT: To investigate two event-oriented methods for evaluating patient satisfaction with radiological services like outpatient computed tomography (CT) examinations. 159 patients (55% men, 45% women) were asked to complete a questionnaire to provide information about their satisfaction with their examination. At first, patients were asked to spontaneously recall notably positive and negative aspects (so-called "critical incidents", critical incident technique = CIT) of the examination. Subsequently a flow chart containing all single steps of the examination procedure was shown to all patients. They were asked to point out the positive and negative aspects they perceived at each step (so-called sequential incident technique = SIT). The CIT-based part of the questionnaire yielded 356 comments (183 positive and 173 negative), which were assigned to one of four categories: interaction of staff with patient, procedure and organization, CT examination, and overall setting of the examination. Significantly more detailed comments regarding individual aspects of the CT examination were elicited in the second part of the survey, which was based on the SIT. There were 1413 statements with a significantly higher number of positive comments (n = 939, 66%) versus negative comments (n = 474, 34%; p < 0.001). The critical and sequential incident techniques are suitable to measure the subjective satisfaction with the delivery of radiological services such as CT examinations. Positive comments confirm the adequacy of the existing procedures, while negative comments provide direct information about how service quality can be improved.
  RöFo - Fortschritte auf dem Gebiet der R 10/2010; 182(11):965-72. · 2.76 Impact Factor
• Article: [CPPD-deposits--an important differential diagnosis in the retro-odontoid space in older men].

  N F Schreiter, R Pflugmacher, R Schröder
  RöFo - Fortschritte auf dem Gebiet der R 09/2007; 179(8):856-8. · 2.76 Impact Factor