Christian Ritter | Universitätsmedizin Göttingen (original) (raw)
Papers by Christian Ritter
Hepatic Medicine: Evidence and Research, 2016
In hepatocellular carcinoma patients with large or multinodal tumors, where curative treatment op... more In hepatocellular carcinoma patients with large or multinodal tumors, where curative treatment options are not feasible, transarterial therapies play a major role. Transarterial chemoembolization (TACE) with drug-eluting beads (DEB-TACE) is a promising new approach due to higher intratumoral and lower systemic concentration of the chemotherapeutic agent compared to conventional TACE (cTACE). In a retrospective analysis, 32 patients with hepatocellular carcinoma who received either DEB or a cTACE were compared regarding survival time, disease recurrence, and side effects such as pain and fever. No significant differences could be detected between the cTACE and DEB-TACE groups with regard to mean hospital stay, appearance of postinterventional fever, or 30-day mortality. However, the application of intravenous analgesics as postinterventional pain medication was needed more often in patients treated with DEB-TACE (57.1% vs 12.5%, P=0.0281). The overall median survival after the initial procedure was 10.8 months in the cTACE group and 9.2 months in the DEB-TACE group, showing no significant difference. No survival benefit for patients treated with either DEB-TACE or cTACE was observed. Surprisingly, a higher rate of postinterventional pain could be detected after DEB-TACE.
Open Journal of Thoracic Surgery, 2012
We present a unique case of a 49-year-old woman presenting with a bilateral chylothorax sustained... more We present a unique case of a 49-year-old woman presenting with a bilateral chylothorax sustained after minor injury. This condition developed secondarily to minor neck injury which resulted in left side cervical swelling. First treatment was conservative. Surgical intervention was nevertheless necessary to remove a cervical cyst contiguous with the thoracic duct.
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2005
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2014
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2012
Clinical Nuclear Medicine, 2014
Here we report on a 51-year-old man with the primary diagnosis of cholangiocarcinoma. Workup with... more Here we report on a 51-year-old man with the primary diagnosis of cholangiocarcinoma. Workup with CT and contrast-enhanced ultrasound revealed an additional lesion in the spleen, raising the concern for metastasis. Combined FDG PET/CT revealed a different metabolic pattern, making a metastasis unlikely. Histopathology of the splenic lesion confirmed sclerosing angiomatoid nodular transformation, a rare benign lesion of the spleen.
Investigative radiology, Jan 24, 2015
The aims of this study were to compare 3 contrast agents and to define feasible doses for quantit... more The aims of this study were to compare 3 contrast agents and to define feasible doses for quantitative lung perfusion imaging using the dual-bolus approach in dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). Ten healthy volunteers (6 males, 4 females; mean age, 23.5 years) underwent DCE-MRI at 1.5 T using a 3D FLASH sequence. After a prebolus, 3 doses of gadopentetate dimeglumine (Gd-DTPA), gadofosveset, and gadobenate dimeglumine (Gd-BOPTA) were evaluated. Dose regimes were as follows: Gd-DTPA: 3.0 mL, 6.0 mL, and 12.0 mL with 1.5 mL prebolus; gadofosveset: 1.5 mL, 3.0 mL, and 6.0 mL with 0.8 mL prebolus; and Gd-BOPTA: 1.5 mL, 3.0 mL, and 6.0 mL with 0.8 mL prebolus.Pulmonary blood flow (PBF), pulmonary distribution volume, and mean transit time were assessed for each bolus. Region of interest measurements were used to determine the arterial input function (AIF) in the pulmonary trunk and signal intensities in lung parenchyma. Two radiologists independently rated t...
Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 19, 2017
Endomyocardial biopsies (EMB) are an important diagnostic tool for myocarditis and other infiltra... more Endomyocardial biopsies (EMB) are an important diagnostic tool for myocarditis and other infiltrative cardiac diseases. Routinely, biopsies are obtained under fluoroscopic guidance with a substantial radiation burden. Despite procedural success, there is a large sampling error caused by missing the affected myocardium. Therefore, multiple (>6) biopsies are taken in the clinical setting. In cardiovascular magnetic resonance (CMR), late gadolinium enhancement (LGE) depicts areas of affected myocardium in myocarditis or in other infiltrative cardiomyopathies. Thus, targeted biopsy under real-time CMR image guidance might reduce the problem of sampling error. Seven minipigs of the Goettingen strain underwent radiofrequency ablation in the left ventricle. At least two focal lesions were induced on the lateral wall in five and the apex in two animals. Each ablation lesion was created by two consecutive 30 sec ablations (max. 30 W, temperature 60-64 °C). Biopsies were taken immediately ...
The international journal of cardiovascular imaging, Jan 18, 2017
Left atrial (LA) enlargement and dysfunction are markers of chronic diastolic dysfunction and an ... more Left atrial (LA) enlargement and dysfunction are markers of chronic diastolic dysfunction and an important predictor of adverse cardiovascular and cerebrovascular outcomes. Accordingly, accurate quantification of left atrial volume (LAV) and function is needed. In routine clinical cardiovascular magnetic resonance (CMR) imaging the biplane area-length method (Bi-ALM) is frequently applied due to time-saving image acquisition and analysis. However, given the varying anatomy of the LA we hypothesized that the diagnostic accuracy of the Bi-ALM is not sufficient and that results would be different from a precise volumetric assessment of transversal multi-slice cine images using Simpson's method. Thirty one patients of the FIND-AFRANDOMISED-study with status post acute cerebral ischemia (mean age 70.5 ± 6.2 years) received CMR imaging at 3T. The study protocol included cine SSFP sequences in standard 2- and 4 CV and a stack of contiguous slices in transversal orientation. Total, pass...
European Journal of Nuclear Medicine and Molecular Imaging, 2015
Binding of (68)Ga-PSMA-HBED-CC ((68)Ga-PSMA) at prostate cancer (PC) cells increases over time. A... more Binding of (68)Ga-PSMA-HBED-CC ((68)Ga-PSMA) at prostate cancer (PC) cells increases over time. A biphasic protocol may help separating benign from tumor lesions. The aim of this study was the retrospective evaluation of a diagnostic incremental value of a dual-time point (biphasic) (68)Ga-PSMA-PET/CT in patients with prostate cancer. Retrospective analysis of 35 consecutive patients (49-78 years, median 71) with newly diagnosed PC (12/35) or recurrence of PC (23/35). PET/CT (Gemini TF16, Philips) was acquired 1 h and 3 h p. i. of 140-392 MBq (300 MBq median) (68)Ga-PSMA, followed by a diagnostic contrast CT. PET findings were correlated with histology or unequivocal CT findings. Semiquantitative PET data (SUVmax, SUV mean) were acquired and target-to-background-ratios (T/B-ratio) were calculated for benign and malign lesions for both time points. Size of lymph nodes (LN) on diagnostic CT was recorded. Statistical analysis was performed for assessment of significant changes of semiquantitative PET-parameters over time and for correlation of size and uptake of lymph nodes. One hundred and four lesions were evaluated. Sixty lesions were referenced by histology or unequivocal CT findings, including eight (13.3 %) histopathologically benign lymph nodes, 12 (20 %) histopathologically lymph node metastases, 12 (20 %) primary tumors, three (5 %) local recurrences, and 25 (41.7 %) bone metastases. Forty-four lesions were axillary LN with normal CT-appearance. Benign lesions had significantly lower SUVmax and T/B-ratios compared with malignant findings. Malign lesions showed a significant increase of both parameters over time compared to benign findings. There was no correlation between LN size and SUVmax. The sensitivity, specificity, the positive predictive value and negative predictive value of PET/CT regarding pelvic LN was 94 %, 99 %, 89 %, and 99.5 %, respectively. In contrast to benign tissues, the uptake of proven tumor lesions increases on (68)Ga-PSMA-PET/CT over time. A biphasic PET-study may lead to a better detection of tumor lesions in unequivocal findings.
RöFo - Fortschritte auf dem Gebiet der R
MR stress perfusion imaging of the heart allows the quantification of myocardial perfusion and th... more MR stress perfusion imaging of the heart allows the quantification of myocardial perfusion and the evaluation of myocardial perfusion reserve (MPR) and the ratio of subendocardial to subepicardial perfusion at rest and under adenosine stress. The aim of this study was to evaluate a high-resolution GRAPPA sequence for quantitative MR first pass perfusion imaging in healthy volunteers. First pass stress and rest perfusion studies were performed on 10 healthy volunteers using a 1.5 T MR scanner with a multislice SR-TrueFISP first pass perfusion sequence with a GRAPPA algorithm (acceleration factor 3) in prebolus technique and an image resolution of 1.8 x 1.8 mm. For the comparison group, we examined 12 different healthy volunteers with a standard first pass perfusion SR-TrueFISP sequence using a resolution of 2.7 x 3.3 mm. Myocardial contours were manually delineated followed by an automatic division of the myocardium into two rings with an equal thickness for the subendo- and subepicardial layer. Eight sectors per slice were evaluated using contamination and baseline correction. Using the GRAPPA sequence, the ratio of subendo- to subepimyocardial perfusion was 1.18 +/- 0.32 for the examination at rest. Under pharmacologically induced stress, the ratio was 1.08 +/- 0.27. For the standard sequence the ratio was 1.15 +/- 0.28 at rest and 1.11 +/- 0.33 under stress. For the high resolution sequence higher mean values for the subendo- to subepimyocardial ratio were obtained with comparable standard deviations. The difference between the sequences was not significant. The evaluation of subendomyocardial and subepimyocardial perfusion is feasible with a high-resolution first pass perfusion sequence. The use of a higher resolution to avoid systematic error leads to increased image noise. However, no relevant reduction in the quantitative perfusion values under stress and at rest was able to be depicted.
RöFo - Fortschritte auf dem Gebiet der R
Magnetic resonance in medicine, Jan 28, 2015
To reduce saturation effects in the arterial input function (AIF) estimation of quantitative myoc... more To reduce saturation effects in the arterial input function (AIF) estimation of quantitative myocardial first-pass saturation recovery perfusion imaging by employing a model-based reconstruction. Imaging was performed with a saturation recovery prepared radial FLASH sequence. A model-based reconstruction was applied for reconstruction. By exploiting prior knowledge about the relaxation process, an image series with different saturation recovery times was reconstructed. By evaluating images with an effective saturation time of approximately 3 ms, saturation effects in the AIF determination were reduced. In a volunteer study, this approach was compared with a standard prebolus technique. In comparison to the low-dose injection of a prebolus acquisition, saturation effects were further reduced in the AIFs determined using the model-based approach. These effects, which were clearly visible for all six volunteers, were reflected in a statistically significant difference of up to 20% in t...
PURPOSE Friedreich Ataxia (FA) being the most frequent ataxia (approx. 75%) in Caucasian adolesce... more PURPOSE Friedreich Ataxia (FA) being the most frequent ataxia (approx. 75%) in Caucasian adolescents is related with cardiomyopathy, which is often life limiting. To detect local myocardial motion abnormalities in FA patients, we initiated a prospective study using high temporal and spatial resolution tissue phase mapping (TPM). Patients were matched to age- and gender correlated healthy volunteers. METHOD AND MATERIALS TPM measurements were performed with three-dimensional velocity encoding during free breathing on a 1.5 T scanner. Post-processing was based on Matlab software. It has been shown before that TPM is able to reproducibly detect regional myocardial motion. We examined 18 healthy volunteers and 18 genetically positive tested FA patients . We compared scans of the patients to those of the volunteers. Overall systolic and diastolic global as well as regional septal and lateral wall motion of the heart was assessed. RESULTS In comparison of volunteers and patients there wer...
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2010
Hepatic Medicine: Evidence and Research, 2016
In hepatocellular carcinoma patients with large or multinodal tumors, where curative treatment op... more In hepatocellular carcinoma patients with large or multinodal tumors, where curative treatment options are not feasible, transarterial therapies play a major role. Transarterial chemoembolization (TACE) with drug-eluting beads (DEB-TACE) is a promising new approach due to higher intratumoral and lower systemic concentration of the chemotherapeutic agent compared to conventional TACE (cTACE). In a retrospective analysis, 32 patients with hepatocellular carcinoma who received either DEB or a cTACE were compared regarding survival time, disease recurrence, and side effects such as pain and fever. No significant differences could be detected between the cTACE and DEB-TACE groups with regard to mean hospital stay, appearance of postinterventional fever, or 30-day mortality. However, the application of intravenous analgesics as postinterventional pain medication was needed more often in patients treated with DEB-TACE (57.1% vs 12.5%, P=0.0281). The overall median survival after the initial procedure was 10.8 months in the cTACE group and 9.2 months in the DEB-TACE group, showing no significant difference. No survival benefit for patients treated with either DEB-TACE or cTACE was observed. Surprisingly, a higher rate of postinterventional pain could be detected after DEB-TACE.
Open Journal of Thoracic Surgery, 2012
We present a unique case of a 49-year-old woman presenting with a bilateral chylothorax sustained... more We present a unique case of a 49-year-old woman presenting with a bilateral chylothorax sustained after minor injury. This condition developed secondarily to minor neck injury which resulted in left side cervical swelling. First treatment was conservative. Surgical intervention was nevertheless necessary to remove a cervical cyst contiguous with the thoracic duct.
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2005
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2014
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2012
Clinical Nuclear Medicine, 2014
Here we report on a 51-year-old man with the primary diagnosis of cholangiocarcinoma. Workup with... more Here we report on a 51-year-old man with the primary diagnosis of cholangiocarcinoma. Workup with CT and contrast-enhanced ultrasound revealed an additional lesion in the spleen, raising the concern for metastasis. Combined FDG PET/CT revealed a different metabolic pattern, making a metastasis unlikely. Histopathology of the splenic lesion confirmed sclerosing angiomatoid nodular transformation, a rare benign lesion of the spleen.
Investigative radiology, Jan 24, 2015
The aims of this study were to compare 3 contrast agents and to define feasible doses for quantit... more The aims of this study were to compare 3 contrast agents and to define feasible doses for quantitative lung perfusion imaging using the dual-bolus approach in dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). Ten healthy volunteers (6 males, 4 females; mean age, 23.5 years) underwent DCE-MRI at 1.5 T using a 3D FLASH sequence. After a prebolus, 3 doses of gadopentetate dimeglumine (Gd-DTPA), gadofosveset, and gadobenate dimeglumine (Gd-BOPTA) were evaluated. Dose regimes were as follows: Gd-DTPA: 3.0 mL, 6.0 mL, and 12.0 mL with 1.5 mL prebolus; gadofosveset: 1.5 mL, 3.0 mL, and 6.0 mL with 0.8 mL prebolus; and Gd-BOPTA: 1.5 mL, 3.0 mL, and 6.0 mL with 0.8 mL prebolus.Pulmonary blood flow (PBF), pulmonary distribution volume, and mean transit time were assessed for each bolus. Region of interest measurements were used to determine the arterial input function (AIF) in the pulmonary trunk and signal intensities in lung parenchyma. Two radiologists independently rated t...
Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, Jan 19, 2017
Endomyocardial biopsies (EMB) are an important diagnostic tool for myocarditis and other infiltra... more Endomyocardial biopsies (EMB) are an important diagnostic tool for myocarditis and other infiltrative cardiac diseases. Routinely, biopsies are obtained under fluoroscopic guidance with a substantial radiation burden. Despite procedural success, there is a large sampling error caused by missing the affected myocardium. Therefore, multiple (>6) biopsies are taken in the clinical setting. In cardiovascular magnetic resonance (CMR), late gadolinium enhancement (LGE) depicts areas of affected myocardium in myocarditis or in other infiltrative cardiomyopathies. Thus, targeted biopsy under real-time CMR image guidance might reduce the problem of sampling error. Seven minipigs of the Goettingen strain underwent radiofrequency ablation in the left ventricle. At least two focal lesions were induced on the lateral wall in five and the apex in two animals. Each ablation lesion was created by two consecutive 30 sec ablations (max. 30 W, temperature 60-64 °C). Biopsies were taken immediately ...
The international journal of cardiovascular imaging, Jan 18, 2017
Left atrial (LA) enlargement and dysfunction are markers of chronic diastolic dysfunction and an ... more Left atrial (LA) enlargement and dysfunction are markers of chronic diastolic dysfunction and an important predictor of adverse cardiovascular and cerebrovascular outcomes. Accordingly, accurate quantification of left atrial volume (LAV) and function is needed. In routine clinical cardiovascular magnetic resonance (CMR) imaging the biplane area-length method (Bi-ALM) is frequently applied due to time-saving image acquisition and analysis. However, given the varying anatomy of the LA we hypothesized that the diagnostic accuracy of the Bi-ALM is not sufficient and that results would be different from a precise volumetric assessment of transversal multi-slice cine images using Simpson's method. Thirty one patients of the FIND-AFRANDOMISED-study with status post acute cerebral ischemia (mean age 70.5 ± 6.2 years) received CMR imaging at 3T. The study protocol included cine SSFP sequences in standard 2- and 4 CV and a stack of contiguous slices in transversal orientation. Total, pass...
European Journal of Nuclear Medicine and Molecular Imaging, 2015
Binding of (68)Ga-PSMA-HBED-CC ((68)Ga-PSMA) at prostate cancer (PC) cells increases over time. A... more Binding of (68)Ga-PSMA-HBED-CC ((68)Ga-PSMA) at prostate cancer (PC) cells increases over time. A biphasic protocol may help separating benign from tumor lesions. The aim of this study was the retrospective evaluation of a diagnostic incremental value of a dual-time point (biphasic) (68)Ga-PSMA-PET/CT in patients with prostate cancer. Retrospective analysis of 35 consecutive patients (49-78 years, median 71) with newly diagnosed PC (12/35) or recurrence of PC (23/35). PET/CT (Gemini TF16, Philips) was acquired 1 h and 3 h p. i. of 140-392 MBq (300 MBq median) (68)Ga-PSMA, followed by a diagnostic contrast CT. PET findings were correlated with histology or unequivocal CT findings. Semiquantitative PET data (SUVmax, SUV mean) were acquired and target-to-background-ratios (T/B-ratio) were calculated for benign and malign lesions for both time points. Size of lymph nodes (LN) on diagnostic CT was recorded. Statistical analysis was performed for assessment of significant changes of semiquantitative PET-parameters over time and for correlation of size and uptake of lymph nodes. One hundred and four lesions were evaluated. Sixty lesions were referenced by histology or unequivocal CT findings, including eight (13.3 %) histopathologically benign lymph nodes, 12 (20 %) histopathologically lymph node metastases, 12 (20 %) primary tumors, three (5 %) local recurrences, and 25 (41.7 %) bone metastases. Forty-four lesions were axillary LN with normal CT-appearance. Benign lesions had significantly lower SUVmax and T/B-ratios compared with malignant findings. Malign lesions showed a significant increase of both parameters over time compared to benign findings. There was no correlation between LN size and SUVmax. The sensitivity, specificity, the positive predictive value and negative predictive value of PET/CT regarding pelvic LN was 94 %, 99 %, 89 %, and 99.5 %, respectively. In contrast to benign tissues, the uptake of proven tumor lesions increases on (68)Ga-PSMA-PET/CT over time. A biphasic PET-study may lead to a better detection of tumor lesions in unequivocal findings.
RöFo - Fortschritte auf dem Gebiet der R
MR stress perfusion imaging of the heart allows the quantification of myocardial perfusion and th... more MR stress perfusion imaging of the heart allows the quantification of myocardial perfusion and the evaluation of myocardial perfusion reserve (MPR) and the ratio of subendocardial to subepicardial perfusion at rest and under adenosine stress. The aim of this study was to evaluate a high-resolution GRAPPA sequence for quantitative MR first pass perfusion imaging in healthy volunteers. First pass stress and rest perfusion studies were performed on 10 healthy volunteers using a 1.5 T MR scanner with a multislice SR-TrueFISP first pass perfusion sequence with a GRAPPA algorithm (acceleration factor 3) in prebolus technique and an image resolution of 1.8 x 1.8 mm. For the comparison group, we examined 12 different healthy volunteers with a standard first pass perfusion SR-TrueFISP sequence using a resolution of 2.7 x 3.3 mm. Myocardial contours were manually delineated followed by an automatic division of the myocardium into two rings with an equal thickness for the subendo- and subepicardial layer. Eight sectors per slice were evaluated using contamination and baseline correction. Using the GRAPPA sequence, the ratio of subendo- to subepimyocardial perfusion was 1.18 +/- 0.32 for the examination at rest. Under pharmacologically induced stress, the ratio was 1.08 +/- 0.27. For the standard sequence the ratio was 1.15 +/- 0.28 at rest and 1.11 +/- 0.33 under stress. For the high resolution sequence higher mean values for the subendo- to subepimyocardial ratio were obtained with comparable standard deviations. The difference between the sequences was not significant. The evaluation of subendomyocardial and subepimyocardial perfusion is feasible with a high-resolution first pass perfusion sequence. The use of a higher resolution to avoid systematic error leads to increased image noise. However, no relevant reduction in the quantitative perfusion values under stress and at rest was able to be depicted.
RöFo - Fortschritte auf dem Gebiet der R
Magnetic resonance in medicine, Jan 28, 2015
To reduce saturation effects in the arterial input function (AIF) estimation of quantitative myoc... more To reduce saturation effects in the arterial input function (AIF) estimation of quantitative myocardial first-pass saturation recovery perfusion imaging by employing a model-based reconstruction. Imaging was performed with a saturation recovery prepared radial FLASH sequence. A model-based reconstruction was applied for reconstruction. By exploiting prior knowledge about the relaxation process, an image series with different saturation recovery times was reconstructed. By evaluating images with an effective saturation time of approximately 3 ms, saturation effects in the AIF determination were reduced. In a volunteer study, this approach was compared with a standard prebolus technique. In comparison to the low-dose injection of a prebolus acquisition, saturation effects were further reduced in the AIFs determined using the model-based approach. These effects, which were clearly visible for all six volunteers, were reflected in a statistically significant difference of up to 20% in t...
PURPOSE Friedreich Ataxia (FA) being the most frequent ataxia (approx. 75%) in Caucasian adolesce... more PURPOSE Friedreich Ataxia (FA) being the most frequent ataxia (approx. 75%) in Caucasian adolescents is related with cardiomyopathy, which is often life limiting. To detect local myocardial motion abnormalities in FA patients, we initiated a prospective study using high temporal and spatial resolution tissue phase mapping (TPM). Patients were matched to age- and gender correlated healthy volunteers. METHOD AND MATERIALS TPM measurements were performed with three-dimensional velocity encoding during free breathing on a 1.5 T scanner. Post-processing was based on Matlab software. It has been shown before that TPM is able to reproducibly detect regional myocardial motion. We examined 18 healthy volunteers and 18 genetically positive tested FA patients . We compared scans of the patients to those of the volunteers. Overall systolic and diastolic global as well as regional septal and lateral wall motion of the heart was assessed. RESULTS In comparison of volunteers and patients there wer...
RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren, 2010