Time- and dose-dependent volume decreases in subcortical grey matter structures of glioma patients after radio(chemo)therapy.

Background and purpose: Radiotherapy (RT) is an adjuvant treatment option for glioma patients. Side effects include tissue atrophy, which might be a contributing factor to neurocognitive decline after treatment. The goal of this study was to determine potential atrophy of the hippocampus, amygdala, thalamus, putamen, pallidum and caudate nucleus in glioma patients having undergone magnetic resonance imaging (MRI) before and after RT. Materials and methods: Subcortical volumes were measured using T1-weighted MRI from patients before RT (N = 91) and from longitudinal follow-ups acquired in three-monthly intervals (N = 349). The volumes were normalized to the baseline values, while excluding structures touching the clinical target volume (CTV) or abnormal tissue seen on FLAIR imaging. A multivariate linear effects model was used to determine if time after RT and mean RT dose delivered to the corresponding structures were significant predictors of tissue atrophy. Results: The hippocampus, amygdala, thalamus, putamen, and pallidum showed significant atrophy after RT as function of both time after RT and mean RT dose delivered to the corresponding structure. Only the caudate showed no dose or time dependant atrophy. Conversely, the hippocampus was the structure with the highest atrophy rate of 5.2 % after one year and assuming a mean dose of 30 Gy. Conclusion: The hippocampus showed the highest atrophy rates followed by the thalamus and the amygdala. The subcortical structures here found to decrease in volume indicative of radiosensitivity should be the focus of future studies investigating the relationship between neurocognitive decline and RT.

Overestimation of grey matter atrophy in glioblastoma patients following radio(chemo)therapy.

OBJECTIVE: Brain atrophy has the potential to become a biomarker for severity of radiation-induced side-effects. Particularly brain tumour patients can show great MRI signal changes over time caused by e.g. oedema, tumour progress or necrosis. The goal of this study was to investigate if such changes affect the segmentation accuracy of normal appearing brain and thus influence longitudinal volumetric measurements. MATERIALS AND METHODS: T1-weighted MR images of 52 glioblastoma patients with unilateral tumours acquired before and three months after the end of radio(chemo)therapy were analysed. GM and WM volumes in the contralateral hemisphere were compared between segmenting the whole brain (full) and the contralateral hemisphere only (cl) with SPM and FSL. Relative GM and WM volumes were compared using paired t tests and correlated with the corresponding mean dose in GM and WM, respectively. RESULTS: Mean GM atrophy was significantly higher for full segmentation compared to cl segmentation when using SPM (mean ± std: ΔVGM,full = - 3.1% ± 3.7%, ΔVGM,cl = - 1.6% ± 2.7%; p < 0.001, d = 0.62). GM atrophy was significantly correlated with the mean GM dose with the SPM cl segmentation (r = - 0.4, p = 0.004), FSL full segmentation (r = - 0.4, p = 0.004) and FSL cl segmentation (r = -0.35, p = 0.012) but not with the SPM full segmentation (r = - 0.23, p = 0.1). CONCLUSIONS: For accurate normal tissue volume measurements in brain tumour patients using SPM, abnormal tissue needs to be masked prior to segmentation, however, this is not necessary when using FSL.

Reduced diffusion in white matter after radiotherapy with photons and protons.

BACKGROUND AND PURPOSE: Radio(chemo)therapy is standard in the adjuvant treatment of glioblastoma. Inevitably, brain tissue surrounding the target volume is also irradiated, potentially causing acute and late side-effects. Diffusion imaging has been shown to be a sensitive method to detect early changes in the cerebral white matter (WM) after radiation. The aim of this work was to assess possible changes in the mean diffusivity (MD) of WM after radio(chemo)therapy using Diffusion-weighted imaging (DWI) and to compare these effects between patients treated with proton and photon irradiation. MATERIALS AND METHODS: 70 patients with glioblastoma underwent adjuvant radio(chemo)therapy with protons (n = 20) or photons (n = 50) at the University Hospital Dresden. MRI follow-ups were performed at three-monthly intervals and in this study were evaluated until 33 months after the end of therapy. Relative white matter MD changes between baseline and all follow-up visits were calculated in different dose regions. RESULTS: We observed a significant decrease of MD (p < 0.05) in WM regions receiving more than 20 Gy. MD reduction was progressive with dose and time after radio(chemo)therapy (maximum: -7.9 ± 1.2% after 24 months, ≥50 Gy). In patients treated with photons, significant reductions of MD in the entire WM (p < 0.05) were seen at all time points. Conversely, in proton patients, whole brain MD did not change significantly. CONCLUSIONS: Irradiation leads to measurable MD reduction in white matter, progressing with both increasing dose and time. Treatment with protons reduces this effect most likely due to a lower total dose in the surrounding white matter. Further investigations are needed to assess whether those MD changes correlate with known radiation induced side-effects.

Comparison of sequential and high-pitch-spiral coronary CT-angiography: image quality and radiation exposure.

New protocols for coronary computed tomography angiography (CCTA) could lower the radiation dose for patients but influence the image quality. To compare image quality and radiation exposure in step-and-shoot CCTA and high-pitch spiral CCTA. Fifty-nine pairs of patients matched for weight, height, sex and heart rate were included in this study (74 m, 44 f, average age 60 years, age range 29-94 years). Step-and-shoot CCTA and high-pitch spiral CCTA was performed on a third generation dual-source CT in equally sized patient groups. The signal-to-noise ratio (SNR) in the ascending aorta and the coronary arteries were determined for each dataset. Image quality was rated using a five-point scale. We used the t-test for paired samples to compare SNR and effective dose, and the Wilcoxon test to compare image quality scores. Mean effective dose for the step-and-shoot protocol (4.15 ± 3.07 mSv) was significantly higher in comparison to the high-pitch spiral protocol (1.2 ± 0.69 mSv; p < 0.0001). Mean SNR was higher with the step-and-shoot protocol compared to the high-pitch spiral protocol in the aorta, in the left main and peripheral coronary arteries (p < 0.01), in the proximal right coronary artery (p = 0.027). Image quality scores were significantly better for the step-and-shoot protocol (p = 0.0003). Step-and-shoot CCTA has significantly better SNR and overall image quality compared to high-pitch spiral CCTA, but with a mean effective dose more than thrice as high.

Clinical Relevance of Computed Tomography Pulmonary Venography.

BACKGROUND: In clinical routine, the pulmonary contrast-enhanced chest computer tomography (CT) is usually focussed on the pulmonary arteries. The purpose of this pictorial essay is to raise the clinicians' awareness for the clinical relevance of CT pulmonary venography. CASE PRESENTATION: A pictorial case series illustrates the clinical consequences of different pulmonary venous pathologies on systemic, pulmonary and bronchial circulation. CONCLUSION: Computed tomography pulmonary venography must be considered before atrial septal defect (ASD) closure and pulmonary lobectomy. Computed tomography pulmonary venography should be considered for patients with right ventricular overload and pulmonary hypertension, as well as for patients with unclear recurrent pulmonary infections, progressive dyspnoea, pleural effusions, haemoptysis, and for patients with respiratory distress after lung-transplantation.

Evaluation and automatic correction of metal-implant-induced artifacts in MR-based attenuation correction in whole-body PET/MR imaging.

The aim of this paper is to describe a new automatic method for compensation of metal-implant-induced segmentation errors in MR-based attenuation maps (MRMaps) and to evaluate the quantitative influence of those artifacts on the reconstructed PET activity concentration. The developed method uses a PET-based delineation of the patient contour to compensate metal-implant-caused signal voids in the MR scan that is segmented for PET attenuation correction. PET emission data of 13 patients with metal implants examined in a Philips Ingenuity PET/MR were reconstructed with the vendor-provided method for attenuation correction (MRMap(orig), PET(orig)) and additionally with a method for attenuation correction (MRMap(cor), PET(cor)) developed by our group. MRMaps produced by both methods were visually inspected for segmentation errors. The segmentation errors in MRMap(orig) were classified into four classes (L1 and L2 artifacts inside the lung and B1 and B2 artifacts inside the remaining body depending on the assigned attenuation coefficients). The average relative SUV differences (ε(rel)(av)) between PET(orig) and PET(cor) of all regions showing wrong attenuation coefficients in MRMap(orig) were calculated. Additionally, relative SUV(mean) differences (ε(rel)) of tracer accumulations in hot focal structures inside or in the vicinity of these regions were evaluated. MRMap(orig) showed erroneous attenuation coefficients inside the regions affected by metal artifacts and inside the patients' lung in all 13 cases. In MRMap(cor), all regions with metal artifacts, except for the sternum, were filled with the soft-tissue attenuation coefficient and the lung was correctly segmented in all patients. MRMap(cor) only showed small residual segmentation errors in eight patients. ε(rel)(av) (mean ± standard deviation) were: (-56 ± 3)% for B1, (-43 ± 4)% for B2, (21 ± 18)% for L1, (120 ± 47)% for L2 regions. ε(rel) (mean ± standard deviation) of hot focal structures were: (-52 ± 12)% in B1, (-45 ± 13)% in B2, (19 ± 19)% in L1, (51 ± 31)% in L2 regions. Consequently, metal-implant-induced artifacts severely disturb MR-based attenuation correction and SUV quantification in PET/MR. The developed algorithm is able to compensate for these artifacts and improves SUV quantification accuracy distinctly.

Comparative study of elbow disorders in young high-performance gymnasts.

The study aimed to investigate the prognosis of osteochondral affection (e.g., osteochondritis dissecans (OCD), cartilage lesions, fractures and bone edema in the elbows of high-performance gymnasts (n=30) compared to prognosis results with athletes not undergoing excessive stress on the upper extremity (n=29). The study also tested a novel isotropic 3D-FSE-sequence (CUBE) technique as an early diagnostic modality. Standard protocol was used to conduct the MRI examinations, which were then compared to results from the CUBE - sequence. The gymnast group (p=0.012) presented a significantly higher prevalence of complaints in the elbow joint compared to the other athlete group. Furthermore, osteochondral lesions in MRIs appeared more frequently in the group of gymnasts (n=10, 33%, p=0.033), including 7 cases (23%) of OCD. In the control athlete group 2 asymptomatic cases of OCD and one case of bone edema were detected. The MRI investigation with the CUBE - sequence showed similar results as the standard MRI protocol in terms of the diagnosis sensitivity. The current study indicates that juvenile gymnasts are at a higher risk for osteochondral lesions of the elbow than athletes without excessive stress on the upper extremities.

Influence and compensation of truncation artifacts in MR-based attenuation correction in PET/MR.

UNLABELLED: The goal of this article is to quantify the influence of truncation artifacts in the magnetic resonance (MR)-based attenuation map (MRMap) on reconstructed positron emission tomography (PET) image volumes and to propose a new method for minimizing this influence. METHODS: PET data sets of 20 patients investigated in a Philips Ingenuity PET/MR were reconstructed with and without applying two different methods for truncation compensation (TC1 vendor-provided, TC2 newly developed). In this patient group, the extent of truncation artifacts and quality of the truncation compensation (TC) was assessed visually in the MRMaps. In three additional patients MRMaps generated by algorithm TC2 could be compared to the ground truth of transmission-based attenuation maps obtained with a Siemens ECAT HR(+) scanner. The influence of truncation on regional SUVs in lesions, other hot structures (bladder, kidney, myocardium) and the arms was assessed in suitable volume of interests (VOI). RESULTS: Truncation compensated MRMaps exhibited residual artifacts in the arms in 16 patients for algorithm TC1 and to a lesser extent in eight patients for algorithm TC2. Compared to the transmission-based attenuation maps algorithm TC2 slightly overestimated the size of the truncated arms by 0.3 cm in the radial direction. Without truncation compensation, VOIs located in the trunk showed an average SUVmax underestimation of less than 5.4% relative to the results obtained with TC2. Inside the patients' arms underestimations up to 46.5% were found. CONCLUSION: In the trunk, standardized uptake values (SUV) underestimations due to truncation artifacts in the MRMap are rather small. Inside the arms, severe SUV underestimations can occur. Therefore, reliable TC is mandatory and can be achieved by applying the newly developed algorithm TC2 which has yielded promising results so far. Implementation of the proposed method is straightforward and should be easily adaptable to other PET/MR systems.

[Hemoptysis because of pulmonary vein stenosis and occlusion after pulmonary vein isolation for atrial fibrillation]. / Hämoptysen infolge Pulmonalvenenstenose und -verschluss nach Pulmonalvenen-Isolation bei Vorhofflimmern.

HISTORY AND ADMISSION FINDINGS: A 49-year-old woman was admitted because of hemoptysis for four months. Several bronchoscopies and thoracic computed tomographies at other hospitals had not revealed the cause of the sustained hemoptysis. Eight months before admission she had undergone pulmonary vein ablation (PVA) for paroxysmal atrial fibrillation. After the PVA she had initially received oral anticoagulation, but this had been stopped because of the hemoptysis. Physical examination at admission to our hospital was unremarkable except for moderate obesity and arterial hypertension INVESTIGATIONS: Ventilation/perfusion scintigraphy demonstrated combined ventilation and perfusion deficits in the left lower lobe. Transesophageal echocardiography strongly suggested stenoses of the left pulmonary veins. 3-D reconstruction of previously recorded computed tomographic images showed absence of the left inferior pulmonary vein (LIPV) and marked stenosis of the left superior pulmonary vein (LSPV). DIAGNOSIS: It was confirmed that the hemoptysis was caused by stenosis of the left pulmonary veins, resulting from the previous PVA. TREATMENT AND COURSE: Percutaneous transseptal balloon dilatation of the upper and lower pulmonary veins was successfully performed. The patient was put on oral anticoagulation and discharged home free of symptoms. CONCLUSION: Pulmonary vein stenosis must be considered as the most likely cause of hemoptysis and respiratory symptoms after pulmonary vein ablation for atrial fibrillation. Because of ever more frequent interventions to treat atrial fibrillation and other atrial arrhythmias, great clinical vigilance and an interdisciplinary approach is mandatory to assure optimal assessment of patients with acquired pulmonary vein stenosis.

[Acute pulmonary embolism]. / Die akute Lungenembolie.

Acute pulmonary embolism (APE) presents with a broad clinical spectrum ranging from an even asymptomatic course to sudden cardiac death. Because APE is potentially life-threatening every suspicion of APE has to be clarified promptly by validated diagnostic algorithms. On the basis of the patients haemodynamic instability high-risk APE and non-high-risk APE is differentiated. Based on the presence of shock or hypotension every patient with suspicion of APE should promptly be stratified as high-risk APE or non-high-risk APE. There is a considerable difference in the diagnostic and therapeutic algorithms between high-risk and non-high-risk APE. In suspicion of high-risk APE the patients require immediate diagnosis by multidetector CT or echocardiography and immediate recanalization of the occluded pulmonary arteries by thrombolysis or embolectomy. In haemodynamically stable patients sequential diagnostic workup and prompt therapeutic anticoagulation is recommended.

[Minimally invasive management of metastases from gastrointestinal stromal tumors]. / Minimalinvasive Therapieoptionen bei Metastasen gastrointestinaler Stromatumoren.

Minimally invasive radiological procedures can lead to an improvement in the prognosis and the clinical symptoms in cases of metastases of gastro-intestinal stromal tumors (GIST) in the context of multimodal therapy concepts. In the context of interdisciplinary therapy decision-making radiofrequency ablation (RFA) and transarterial tumor embolization should be considered.

[Direct costs for Parkinson's treatment in private neurology practices in Berlin]. / Direkte Kosten der Parkinson-Behandlung : Eine Erhebung in neurologischen Schwerpunktpraxen in Berlin.

BACKGROUND: Aim of this study was to assess the direct costs of Parkinson's disease (PD) within a 3-month period (i.e. the accounting period for the German statutory health insurance) in 12 neurological outpatient practices in Berlin during 2006. MATERIAL AND METHODS: A total of 425 patients (age 69.1+/-9.3 years, 185 females) were recruited, and sociodemographic and clinical data were obtained by a specific questionnaire. The distribution of costs was analyzed based on several clinical and patient parameters. The costs were calculated with different approaches: (1) prospectively, with the practices' accounting according to German uniform scales (GoA, EbM) and (2) retrospectively, with questionnaires for the Parkinson's patients. Costs were calculated according to current German guidelines of the statutory health insurance. Clinical parameters were assessed with a questionnaire for physicians. RESULTS: The direct medical costs totaled 1,667 EUR (range 1,436-1,995 EUR, CI 95%) per patient per 3 months. Charges by physicians were 42 EUR (39-45 EUR, CI 95%) for patients with statutory health insurance and 135 EUR (106-177 EUR, CI 95%) for those with private insurance. Disease severity and disease duration correlated with higher direct medical costs. Motor fluctuations and depression also were major factors influencing cost. CONCLUSION: Our study emphasizes the large economic burden caused mainly by PD medication and hospitalization. For the first time a direct comparison between costs and actual physicians' reimbursement was possible. In combination with further economic studies, this comparison will help to define shortcomings and excesses in PD health care services.

Computed tomography of the human pineal gland for study of the sleep-wake rhythm: reproducibility of a semi-quantitative approach.

PURPOSE: To propose a semi-quantitative computed tomography (CT) protocol for determining uncalcified pineal tissue (UCPT), and to evaluate its reproducibility in modification of studies showing that the degree of calcification is a potential marker of deficient melatonin production and may prove an instability marker of circadian rhythm. MATERIAL AND METHODS: Twenty-two pineal gland autopsy specimens were scanned in a skull phantom with different slice thickness twice and the uncalcified tissue visually assessed using a four-point scale. The maximum gland density was measured and its inverse graded on a non-linear four-point scale. The sum of both scores was multiplied by the gland volume to yield the UCPT. The within-subject variance of UCPT was determined and compared between scans of different slice thickness. RESULTS: The UCPT of the first measurement, in arbitrary units, was 39+/-52.5 for 1 mm slice thickness, 44+/-51.1 for 2 mm, 45+/-34.8 for 4 mm, and 84+/-58.0 for 8 mm. Significant differences of within-subject variance of UCPT were found between 1 and 4 mm, 1 and 8 mm, and 2 and 8 mm slice thicknesses (P<0.05). CONCLUSION: A superior reproducibility of the semi-quantitative CT determination of UCPT was found using 1 and 2 mm slice thicknesses. These data support the use of thin slices of 1 and 2 mm. The benefit in reproducibility from thin slices has to be carefully weighted against their considerably higher radiation exposure.