H Stergar

University Hospital Essen, Essen, North Rhine-Westphalia, Germany

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Publications (21)63.71 Total impact

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    ABSTRACT: This study had three major objectives: 1.) to record the number of concordant (both in PET and CT) pathological lesions in different body regions/organs, 2.) to evaluate the image quality and 3.) to determine both, the quantity and the quality of artefacts in whole body FDG PET/CT scans. Routine whole body scans of 353 patients referred to FDG-PET/CT exams at 4 university hospitals were employed. All potentially malignant lesions in 13 different body regions/organs were classified as either concordant or suspicious in FDG-PET or CT only. In the latter case the diagnostic relevance of this disparity was judged. The image quality in PET and CT was rated as a whole and separately in 5 different body regions. Furthermore we investigated the frequency and site of artefacts caused by metal implants and oral or intravenous contrast media as well as the subjective co-registration quality (in 4 body regions) and the diagnostic impact of such artefacts or misalignment. In addition, the readers rated the diagnostic gain of adding the information from the other tomographic method. In total 1941 lesions (5.5 per patient) were identified, 1094 (56%) out of which were concordant. 602 (71%) out of the 847 remaining lesions were detected only with CT, 245 (29%) were only PET-positive. As expected, CT particularly depicted the majority of lesions in the lungs and abdominal organs. However, the diagnostic relevance was greater with PET-only positive lesions. Most of the PET/CT scans were performed with full diagnostic CT including administration of oral and intravenous contrast media (> 80%). The image quality in PET and CT was rated excellent. Artefacts occurred in more than 60% of the scans and were mainly due to (dental) metal implants and contrast agent. Nevertheless there was almost no impact on diagnostic confidence if reading of the non attenuation corrected PET was included. The co-registration quality in general was also rated as excellent. Misalignment mostly occurred due to patient motion and breathing and led to diagnostic challenges in about 4% of all exams. The diagnostic gain of adding PET to a CT investigation was rated higher than vice versa. As the image quality in both PET and CT was more than satisfying, CT-artefacts almost never led to diagnostic uncertainties and serious misalignment rarely occurred, PET/CT can be considered as suitable for routine use and may replace single PET- and CT-scans. However, additional reading of the non attenuation corrected PET is mandatory to assure best possible diagnostic confidence in PET. Since approximately half of all lesions found in PET/CT were not concordant, at least in a setting with a diagnostic CT the exams need to be reported by both a nuclear medicine physician and a radiologist in consensus.
    Nuklearmedizin 01/2010; 49(4):129-37. · 1.67 Impact Factor
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    ABSTRACT: Morphologic imaging after radiofrequency ablation (RFA) of liver metastases is hampered by rim-like enhancement in the ablation margin, making the identification of local tumor progression (LTP) difficult. Follow-up with PET/CT is compared to follow-up with PET alone and MRI after RFA. Sixteen patients showed 25 FDG-positive colorectal liver metastases in pre-interventional PET/CT. Post-interventional PET/CT was performed 24h after ablation and was repeated after 1, 3 and 6 months and then every 6 months. PET and PET/CT data were compared with MR data sets acquired within 14 days before or after these time points. Either histological proof by biopsy or resection, or a combination of contrast-enhanced CT at fixed time points and clinical data served as a reference. The 25 metastases showed a mean size of 20mm and were treated with 39 RFA sessions. Ten lesions which developed LTP received a second round of RFA; four lesions received three rounds of treatment. The mean follow-up time was 22 months. Seventy-two PET/CT and 57 MR examinations were performed for follow-up. The accuracy and sensitivity for tumor detection was 86% and 76% for PET alone, 91% and 83% for PET/CT and 92% and 75% for MRI, respectively. In comparison to PET alone, PET/CT was significantly better for detecting LTP after RFA. There were no significant differences between MRI and PET/CT. These preliminary results, however, need further verification.
    European Journal of Radiology 09/2008; 67(2):362-71. · 2.51 Impact Factor
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    ABSTRACT: Positron emission tomography (PET) is a functional imaging modality that has been documented to be useful in patient care. The oncological PET imaging is utilized in a wide variety of neoplasms mainly for staging and follow-up, differentiation of equivocal morphological findings, therapy stratification and monitoring. As PET imaging is based on the physiological-mediated distribution of the administered tracer but not on anatomic information, the addition of CT imaging to PET may improve the interpretation of PET. The combined PET/CT offers several potential advantages over PET alone that may influence the clinical routine. PET/CT was introduced into clinical use only 3 years ago and has found widespread application within only 1-2 years. This article summarizes preliminary data of clinical applications for PET/CT in gastrointestinal tumors.
    Abdominal Imaging 07/2008; · 1.91 Impact Factor
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    ABSTRACT: The correct staging of patients with malignant liver tumors before radio-frequency ablation (RFA) is mandatory for successful treatment. Our study aimed to compare the influence on decision to perform RFA of whole-body fluorodeoxyglucose (FDG)-PET/computed tomography (CT) with whole-body contrast-enhanced CT (CE-CT) and PET alone. Fifty-eight patients with known hepatic malignancies (23, liver metastases 35) received FDG-PET/CT before RFA planned with curative intention. CT and PET data were each read separately, PET/CT fusion data were read in consensus afterward by a third reader group. The diagnostic accuracy of CE-CT, PET alone, and PET/CT to identify patients eligible for RFA was compared and the impact on decision was analyzed. The McNemar test with Bonferroni correction was used to test for significant differences. The accuracy and sensitivity to detect correctly intrahepatic and extrahepatic tumor were 94 and 97% for CT, 75 and 54% for PET, and 97 and 95% for PET/CT. The differences between CT and PET, as well as between PET/CT and PET, were statistically significant, but there was no significant difference between PET/CT and CT alone (P>0.65). PET alone, CE-CT, and PET/CT correctly identified 32, 55, and 57 patients, respectively. Again, PET/CT showed no significant advantage over CE-CT. Both imaging methods performed significantly better than PET alone (P<0.0001). Forty-three (74%) of 58 patients underwent RFA with curative intention. Whole-body imaging changed patient management in 26% of the patients planned for curative intended RFA, yet there was no significant difference between CE-CT and PET/CT.
    Nuclear Medicine Communications 07/2008; 29(7):599-606. · 1.38 Impact Factor
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    ABSTRACT: Objective of this prospective study was to evaluate the role of somatostatin receptor scintigraphy (SRS) in advanced renal cell carcinoma (RCC) with respect to potential therapy with somatostatin analogue (SST-A) and to assess the response rate under therapy with SST-A. 16 patients with documented progression of histologically confirmed advanced RCC were included. Planar whole-body SRS was performed 4, 24 and 48 h post i.v. injection of 175-200 MBq 111In-pentetreoide. 5 and 25 h p.i. SPECT of thorax and abdomen were performed. Documentation of somatostatin receptor expression via SRS in >50% of known tumour lesions was the criteria for treatment start with SST-A (Sandostatin LAR-Depot 30 mg i.m. every four weeks). In 9/16 of the patients SRS showed at least one metastasis with moderate (n = 5) or intense (n = 4) tracer uptake. Lesion-based SRS evaluation showed only 12.1% (20/165) of all metastases. Most false-negative lesions were located in the lungs. In two patients, the majority of the known metastases was SRS positive and these patients received SST-A therapy. The first radiographic evaluation after a two-month interval showed progressive disease in both patients. We conclude that SRS is of limited value in staging of advanced RCC. In our patients SST-A did not result in a growth control of RCC. Consequently, the use of SST-A in advanced RCC seems to be no relevant therapeutic option.
    Nuklearmedizin 01/2008; 47(3):127-31. · 1.67 Impact Factor
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    ABSTRACT: Identification of primary tumor in patients with cervical lymph node metastasis of unknown primary (MUO) has a great impact on therapy approach and potentially on patient prognosis. To assess the diagnostic accuracy of combined positron emission tomography(PET)/computer tomography (CT) for primary tumor detection in cervical metastases of unknown origin compared to PET, CT, and PET+CT side-by-side evaluation. 39 consecutive patients (eight women, 31 men; mean age 59.9 ± 11.2 years) with MUO were enrolled in this study. PET/CT images were obtained 1 hour after injection of 350 MBq of fluorodeoxyglucose. Oral and intravenous contrast agents were administered in all patients to ensure diagnostic CT data. Fused PET/CT data were evaluated for primary tumor detection. Diagnostic accuracy was calculated and compared with CT alone, PET alone, and side-by-side PET+CT evaluation.Statistical analysis of differences in diagnostic performance between the different imaging procedures was based on the McNemar test. Fused PET/CT depicted the primary tumor in 11 of 39 (28%) patients. In 28(72%) patients, the primary tumor remained occult. CT revealed the primary in five(13%), PET alone in 10 (26%), and side-by-side evaluation of PET+CT in 10 (26%) of 39 patients. Statistical analysis showed no significant differences between the imaging modalities. PET, side-by-side PET+CT, and PET/CT revealed similar detection rates for primary tumors in cervical MUO patients. Therefore, cervical metastases of an unknown primary may be assessed with either of these imaging modalities. Detection rates with CT were substantially lower. Thus, inclusion of functional data for assessment of cervical MUO patients must be recommended.
    Acta Radiologica 11/2007; 48(10):1101-8. · 1.33 Impact Factor
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    ABSTRACT: We aimed to compare the value of combined positron emission tomography (PET)/CT, PET+CT (viewed side by side), CT alone and PET alone concerning the rTNM stage and influence on therapy in patients with recurrent breast cancer. 44 patients with suspicion of recurrent breast cancer underwent whole-body [18F]-2-fluoro-2-deoxy-d-glucose (FDG)-PET/CT. Images of combined PET/CT, PET+CT, PET alone and CT alone were evaluated by four blinded reader teams. Diagnostic accuracies and influence on therapy were compared. Histology and a mean clinical follow up of 456 days served as the standard of reference. Differences between the staging procedures were tested for statistical significance by McNemar's test. Overall TNM tumour stage was correctly determined in 40/44 patients with PET/CT, in 38/44 with PET+CT, in 36/44 with PET alone and in 36/44 patients with CT alone. No statistically significant difference was detected between all tested imaging modalities. PET/CT changed the therapy in two patients compared with PET+CT, in four patients compared with PET alone and in five patients compared with CT alone. Combined PET/CT appeared to be more accurate in assessing the rTNM and showed a moderate impact on therapy over PET and CT. Minor improvements were noted when compared with PET+CT. Experienced readers might therefore be able to provide accurate staging results for further therapy from separately acquired studies.
    The British journal of radiology 08/2007; 80(955):508-15. · 2.11 Impact Factor
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    ABSTRACT: To evaluate the influence of the introduction of combined PET/CT scanners into clinical routine. This investigation addresses the quantitative changes between PET/CT and stand alone PET. The study included all examinations performed on stand alone PET- or PET/CT-scanners within 12 month prior to and after implementation of PET/CT. The final data analysis included five university hospitals and a total number of 15 497 exams. We distinguished exams on stand alone tomographs prior to and after installation of the combined device as well as PET/CT scans particularly with regard to disease entities. Various further parameters were investigated. The overall number of PET scans (PET and PET/CT) rose by 146% while the number of scans performed on stand alone scanners declined by 22%. Only one site registered an increase in stand alone PET. The number of exams for staging in oncology increased by 196% while that of cardiac scans decreased by 35% and the number of scans in neurology rose by 47%. The use of scans for radiotherapy planning increased to 7% of all PET/CT studies. The increase of procedures for so-called classic PET oncology indications was moderate compared to the more common tumors. An even greater increase was observed in some rare entities. The introduction of PET/CT led to more than a doubling of overall PET procedures with a main focus on oncology. Some of the observed changes in scanning frequency may be caused by a rising availability of new radiotracers and advancements of competing imaging methods. Nevertheless the evident increase in the use of PET/CT for the most common tumour types demonstrates its expanding role in cancer staging. The combination of molecular and morphologic imaging has not only found its place but is still gaining greater importance with new developments in technology and radiochemistry.
    Nuklearmedizin 02/2007; 46(2):57-64. · 1.67 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2007; 179.
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    ABSTRACT: Staging of patients with colorectal cancer often requires a multimodality, multistep imaging approach. Colonography composed of a combined modality of positron emission tomography (PET) and computed tomography (CT) provides whole-body tumor staging in a single session. To determine the staging accuracy of whole-body PET/CT colonography compared with the staging accuracies of CT followed by PET (CT + PET) and CT alone and to evaluate the effect of PET/CT colonography on therapy planning compared with conventional staging (CT of the abdomen and thorax and optical colonoscopy). Prospective study of 47 patients enrolled between May 2004 and June 2006 with clinical findings and optical colonoscopy that suggested primary colorectal cancer (mean [SD] age, 71 [11] years; range, 47-92 years). Patients underwent whole-body PET/CT colonography 1 day after colonoscopy. The study was conducted at a university hospital with a mean (SD) follow-up of 447 (140) days (range, 232-653 days). Correct classification of overall TNM stage using PET/CT colonography compared with CT + PET and CT alone. Secondary outcome measures were the accurate assessment of T-stage, N-stage, and M-stage by PET/CT colonography compared with CT + PET and CT alone and the effect of PET/CT colonography on therapy planning. Of the 47 patients with a total of 50 lesions, the overall TNM stage was correctly determined for 37 lesions with PET/CT colonography (74%; 95% confidence interval [CI], 60%-85%), 32 lesions with CT + PET (64%; 95% CI, 49%-77%), and 26 lesions with CT alone with a 0.7-cm node threshold (52%; 95% CI, 37%-66%). Compared with optimized abdominal CT staging alone, PET/CT colonography was significantly more accurate in defining TNM stage (difference, 22%; 95% CI, 9%-36%; P=.003), which was mainly based on a more accurate definition of the T-stage. Differences were not detected for defining N-stage between PET/CT colonography and CT alone with a threshold of 0.7 cm for malignant nodes but were detected with a threshold of 1 cm. Differences were not detected in defining M-stage separately or when comparing the accuracies of PET/CT colonography with CT + PET. PET/CT colonography affected consecutive therapy decisions in 4 patients (9%; 95% CI, 2.4%-20.4%) compared with conventional staging (CT alone and colonoscopy). In this preliminary study, PET/CT colonography is at least equivalent to CT + PET for tumor staging in patients with colorectal cancer. Thus, PET/CT colonography in conjunction with optical colonoscopy may be a suitable concept of tumor staging for patients with colorectal cancer.
    JAMA The Journal of the American Medical Association 01/2007; 296(21):2590-600. · 29.98 Impact Factor
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    ABSTRACT: PURPOSE Staging of patients with colorectal cancer often requires a multi-modality, multi-step imaging approach. However, whole-body TNM-staging in a single session is desirable, in order to reduce the time until initiation of the appropriate therapy. The aim of this study was to implement in clinical practice a new staging concept comprising whole-body PET/CT-colonography and colonoscopy and to assess its accuracy concerning TNM staging of patients with colorectal cancer. METHOD AND MATERIALS 52 patients underwent the whole-body PET/CT protocol one day after colonoscopy in a prospective study design. Whole-body PET/CT-colonography was compared to CT-colonography concerning the accuracy for TNM staging. A potential impact on the patients’ management by whole-body PET/CT-colonography was assessed compared to a “conventional” staging concept. This was done by the referring physicians and the PET/CT readers. Histopathology of the surgical specimen, optical colonoscopy, and a further follow-up of 310 days served as the standard of reference. RESULTS PET/CT-colonography proved significantly more accurate in TNM staging than CT-colonography alone (p<0.05), which was mainly based on a more accurate definition of the T-stage with PET/CT-colonography. No statistically significant difference was found when assessing the N-stage or M-stage separately. The “all-in-one” staging concept had an impact on consecutive therapy decisions in 5 patients (10%) compared to the “conventional” staging concept. CONCLUSION A combination of whole-body-PET/CT colonography and optical colonoscopy offers accurate tumor staging. Compared to a multi-modality, multi-step staging concept this whole-body staging algorithm can improve the staging accuracy while shortening the time to definite treatment. CLINICAL RELEVANCE/APPLICATION Whole-body-PET/CT colonography in conjunction with optical colonoscopy might improve the staging accuracy while shortening the time to definite treatment compared to conventional staging concepts.
    Radiological Society of North America 2006 Scientific Assembly and Annual Meeting; 11/2006
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    ABSTRACT: Lymph node staging according to the TNM criteria is an essential part of tumor evaluation. Several morphological and functional imaging procedures are used complementarily in this setting. Dual-modality PET/CT scanners are able to provide anatomical and functional data sets in a single session with accurate image co-registration. Comparative studies between morphological imaging procedures, such as MRI and CT, with co-registered PET/CT demonstrated significantly better lymph node staging with PET/CT than with anatomical procedures alone, regardless of the staged body compartment (head and neck, thorax or abdominal area). Based on more accurate staging results, PET/CT was able to alter the patients' therapy in a significant number of studies. Functional imaging with FDG-PET ([(18)F]-2-fluoro-2-desoxy-D-glucose-positron emission tomography) demonstrated outstanding results in lymph node staging of different tumor diseases. By adding anatomical information to PET, PET/CT outperforms PET alone when assessing the TNM-stage of different malignant diseases. This paper provides an overview concerning the performance of PET/CT in staging lymph nodes for malignant spread and points out benefits and limitations of this new imaging modality.
    European Journal of Radiology 07/2006; 58(3):383-9. · 2.51 Impact Factor
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    ABSTRACT: The aim of this study was to implement an imaging protocol for positron emission tomography/computed tomography (PET/CT) colonography and to combine this protocol with whole body PET/CT tumour staging for a single whole body examination for routine clinical use. A whole body PET/CT protocol for tumour staging and a protocol for PET/CT colonography were integrated into one examination. Fourteen prospective patients with suspected colorectal cancer underwent whole body PET/CT after aqueous bowel distension and pharmacological bowel relaxation. Colonoscopy and histopathology served as the standards of reference in all patients. The modified PET/CT examination detected all but one lesion in the colon. One additional lesion was detected in a patient with incomplete colonoscopy due to high grade luminal stenosis. One polyp with malignant conversion was identified with the modified PET/CT protocol. PET/CT colonography proved accurate in local lymph node staging and staged nine out of 11 patients correctly. Six additional extracolonic tumour sites were detected based on the whole body staging approach. Whole body PET/CT with integrated colonography is technically feasible for whole body staging in patients with colorectal cancer. Based on these initial diagnostic experiences, this integrated protocol may be of substantial benefit in staging patients with colorectal cancer, focusing on patients with incomplete colonoscopy and those with small synchronous bowel lesions.
    Gut 02/2006; 55(1):68-73. · 10.73 Impact Factor
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    ABSTRACT: The aim of this study was to determine the accuracy of dual-modality positron emission tomography(PET)/computed tomography (CT) in the detection of residual tumor after radiofrequency ablation (RFA) of liver metastasis of colorectal cancer. Eleven patients with 16 hepatic metastases (mean size 2.9 cm) from colorectal cancer were enrolled in this study, and 19 RFA procedures and 32 PET/CT examinations were performed. The patients had PET/CT before and after RFA using [18F]-2-fluoro-2-deoxy-D: -glucose. CT images alone were read by two radiologists, PET images alone were evaluated by two nuclear physicians. Fused images were read by one physician of each speciality in consensus. The accuracy for detection of residual tumor by the different imaging modalities following RFA was assessed. Eleven patients with a mean age of 63 (range 55-71) years were evaluated. The mean follow-up period was 393 days. The overall procedure-based sensitivity for detection of residual tumor was 65% for PET and PET/CT and 44% for CT alone. The accuracies were 68% and 47%, respectively. Four patients had residual tumor after RFA, six patients total developed local recurrence. PET/CT therefore possibly proved superior to CT alone when assessing the liver for residual tumor after RFA.
    European Radiology 02/2006; 16(1):80-7. · 4.34 Impact Factor
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2006; 178.
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2006; 178.
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    ABSTRACT: Positron emission tomography (PET) is a functional imaging modality that has been documented to be useful in patient care. Oncologic PET imaging is used for a wide variety of neoplasms, mainly for staging and follow-up, differentiation of equivocal morphologic findings, therapy stratification, and monitoring. Because PET imaging is based on the physiologically mediated distribution of the administered tracer but not on anatomic information, the addition of computed tomography (CT) to PET may improve the interpretation of PET. Combined PET and CT offers several potential advantages over PET alone that may influence the clinical routine. PET/CT was introduced into clinical use only 3 years ago and has found widespread application within only 1 to 2 years. This article summarizes preliminary data of clinical applications for PET/CT in gastrointestinal tumors.
    Abdominal Imaging 01/2006; 31(1):25-35. · 1.91 Impact Factor
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    ABSTRACT: PURPOSE To compare the value of combined PET/CT, PET+CT viewed side by side, CT alone and PET alone concerning the rTNM stage and influence on therapy in patients with recurrent breast cancer. METHOD AND MATERIALS 58 patients with suspicion of recurrent breast cancer underwent whole-body [18F]-2-Fluoro-2-deoxy-D-glucose (FDG) PET/CT. Images of combined PET/CT, PET+CT, PET alone and CT alone were evaluated by four different, blinded reader teams and diagnostic accuracies of the four imaging procedures for assessing the rTNM stage and their influence on therapy were compared. Histology (25 patients) and a mean clinical follow-up of 456 days served as the standard of reference. Differences between the staging procedures were tested for statistical significance by McNemar’s test. RESULTS The overall TNM tumor stage was correctly determined in 54/ 58 patients (93%) with PET/CT, in 52/58 (90%) with PET+CT, in 46/58 (79%) with PET and in 49/58 (84%) patients with CT alone. Combined PET/CT was more accurate in rTNM stage than PET alone (p< 0.05), but no statistically significant difference was detected compared to CT alone (p=0.06) or PET+CT (p=0.5). PET/CT changed the therapy in 2 patients compared to PET+CT, in 8 patients compared to PET alone and in 5 patients compared to CT alone. Concerning the change in patient management differences between PET/CT and PET alone were statistically significant (p<0.05), no statistical significance was found when comparing PET/CT with PET+CT (p=0.05)and CT alone (p=0.06). CONCLUSION Combined PET/CT proved to be more accurate in assessing the rTNM than PET alone with an impact on patient management in patients with recurrent breast cancer. There was a trend to more accurate staging compared to CT alone, though this did not prove to be of statistical significance. Thus, further studies evaluating larger patients populations are needed.
    Radiological Society of North America 2005 Scientific Assembly and Annual Meeting; 12/2005
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2005; 177.
  • Rofo-fortschritte Auf Dem Gebiet Der Rontgenstrahlen Und Der Bildgebenden Verfahren - ROFO-FORTSCHR RONTGENSTRAHL. 01/2005; 177.

Publication Stats

302 Citations
63.71 Total Impact Points

Institutions

  • 2006–2010
    • University Hospital Essen
      • Institut für Diagnostische und Interventionelle Radiologie und Neuroradiologie
      Essen, North Rhine-Westphalia, Germany
  • 2006–2007
    • University of Duisburg-Essen
      • Faculty of Medicine
      Essen, North Rhine-Westphalia, Germany