Christine B. Henk

Brain tumour imaging with PET: a comparison between [18F]fluorodopa and [11C]methionine

Imaging of amino acid transport in brain tumours is more sensitive than fluorine-18 2-fluoro-deoxyglucose positron emission tomography (PET). The most frequently used tracer in this field is carbon-11 methionine (MET), which is unavailable for PET centres without a cyclotron because of its short half-life. The purpose of this study was to evaluate the performance of 3,4-dihydroxy-6-[18F]fluoro-phenylalanine (FDOPA) in this setting, in comparison with MET. Twenty patients with known supratentorial brain lesions were referred for PET scans with FDOPA and MET. The diagnoses were 18 primary brain tumours, one metastasis and one non-neoplastic cerebral lesion. All 20 patients underwent PET with FDOPA (100xa0MBq, 20xa0min p.i.), and 19 of them also had PET scans with MET (800xa0MBq, 20xa0min p.i.). In all but one patient a histological diagnosis was available. In 15 subjects, histology was known from previous surgical interventions; in five of these patients, as well as in four previously untreated patients, histology was obtained after PET. In one untreated patient, confirmation of PET was possible solely by correlation with MRI; a histological diagnosis became available 10 months later. MET and FDOPA images matched in all patients and showed all lesions as hot spots with higher uptake than in the contralateral brain. Standardised uptake value ratios, tumour/contralateral side (mean±SD), were 2.05±0.91 for MET and 2.04±0.53 for FDOPA (NS). The benign lesion, which biopsy revealed to be a focal demyelination, was false positive, showing increased uptake of MET and FDOPA. We conclude that FDOPA is accurate as a surrogate for MET in imaging amino acid transport in malignant cerebral lesions for the purpose of visualisation of vital tumour tissue. It combines the good physical properties of 18F with the pharmacological properties of MET and might therefore be a valuable PET radiopharmaceutical in brain tumour imaging.

Spiral CT of the lung in children with malignant extra-thoracic tumors: distribution of benign vs malignant pulmonary nodules.

Abstract. The purpose of this paper is to clarify the distribution of benign vs malignant pulmonary nodules which are seen on spiral CT in children with malignant extra-thoracic solid tumors. Seventy-four children with known solid, extra-thoracic tumors underwent spiral CT of the chest. According to the initial and follow-up (interval 9.2 ± 4.7 months) findings, the children were graded into four groups: I = normal; II = solitary nodule unchanged at follow-up; III = multiple nodules with one or more than one unchanged at follow-up; and IV = solitary or multiple nodules all changed at follow-up. Nodules without change at follow-up were regarded as benign. Forty-nine children did present with normal pulmonary CT exams. In 7 cases solitary pulmonary nodules were found unchanged (group II) at follow-up and in 2 cases (group III) some of the nodules were stationary. Thus, 12 % (9 of 74) presented with at least one pulmonary nodule that did not change at follow-up. Solitary nodules (in groups II and IV) with a diameter < 5 mm were in 70 % (7 of 10) unchanged at follow-up and regarded as benign. In children with known solid extra-thoracic tumors at initial presentation, 70 % of solitary nodules ( < 5 mm) may be benign. To avoid overstaging, smaller solitary nodules must not automatically be regarded as metastases.

Das Ewing-Sarkom Bildgebende Diagnostik

ZusammenfassungDas Ewing-Sarkom ist ein hochmaligner Tumor des Knochens ungeklärter Herkunft, wobei eine enge Beziehung zu Tumoren neuralen Ursprungs besteht (Ewing-Gruppe). Es muß von anderen Rundzelltumoren wie Lymphom und Neuroblastom sowie vom Osteosarkom differenziert werden. Nativradiologisch manifestiert sich das Ewing-Sarkom als vorwiegend lytische oder lytisch-sklerotische, seltener als überwiegend sklerotische Läsion des Knochens mit einer Begrenzung nach Lodwick Grad III. Hauptsitz des Ewing-Sarkoms sind die Diaphysen und Meta-Diaphysenübergänge langer Röhrenknochen der unteren Extremität. Die Knochenläsion wird immer von einem großen Weichteilanteil begleitet. Die MRT ist heute die unbestrittene Methode der Wahl zur Abklärung der Ausdehnung des Primärtumors, zur Evaluierung des Erfolges der neoadjuvanten Chemotherapie und in der Nachsorge nicht primär chirurgisch resezierter Tumore. Die Knochenszintigraphie hat einen hohen Stellenwert in der Detektion von Skelettmetastasen, die 201Thalliumszintigraphie ist eine neuere Methode, die sich in der Chemotherapieevaluierung als sensitiv erwiesen hat. Die Computertomographie hat als Spiral-CT der Lunge zentrale Bedeutung im Tumorstaging und in der Tumornachsorge, nicht mehr jedoch (mit wenigen Ausnahmen) in der Bildgebung des Primärtumors.SummaryEwing’s sarcoma is a highly malignant neoplasm of the bone whose origin is still uncertain. A strong relationship exists between Ewing’s sarcoma and tumors of neural origin (Ewing family of tumors). Ewing’s sarcoma must be distinguished from other round-cell tumors like lymphoma and neuroblastoma and also must be differentiated from osteogenic sarcomas. On plain radiographs, Ewing’s sarcoma appears as a lytic or mixed lytic-sclerotic, rarely as predominantly sclerotic lesion with margins Lodwick grade III. It is located primarily in the diaphyseal and metadiaphyseal regions of the long bones of the lower extremities. A large soft tissue tumor is usually present. Magnetic resonance imaging is the imaging modality of choice to evaluate the extent of the primary lesion, to monitor the response to neoadjuvant chemotherapy and to follow up non-resected Ewing’s sarcomas. Bone scintigraphy is necessary to detect skeletal metastasis, and 201thallium scanning has been shown to be sensitive in the montitoring of treatment response. Today, computed tomography is not longer used to image the tumor site; however, spiral CT of the lungs plays a central role as a staging and follow-up tool.

Elimination of errors caused by first-order aliasing in velocity encoded cine-MR measurements of postoperative jets after aortic coarctation: in vitro and in vivo validation

Abstract. The aim of this study was to evaluate a velocity-encoded cine-MR (VEC-MR) sequence in measuring flow velocities up to two times the velocity encoding value (VENC) in a flow phantom and to validate the method for assessing poststenotic jet velocities in postoperative patients after aortic coarctation. In vitro, a flow phantom was used (0.5T; TR/TE: 51/8xa0ms, flip angle=30°, FOV=280xa0mm, 128×256 matrix VENC 40 or 80xa0cm/s). On binary images, maximum flow velocities (Vmax) were calculated with a region of interest (ROI, 8 pixels). With aliasing, Vmax was calculated by VENC+(Valiasing). In vivo, 16 postoperative patients after aortic coarctation underwent double-oblique VEC-MR imaging through the aortic arch (ECG triggering, 16 phases/RR, TR=600–800xa0ms, flow-encoding cranio-caudal, VENC=2xa0m/s). Peak systolic velocities were measured and transthoracic Doppler echocardiography (TTDE) was performed. In vitro, there were excellent correlations for MR velocity measurements with and without aliasing (r=0.99) and for true and MR-derived flow velocities (r=0.99). In vivo, there was good correlation between VEC-MR and TTDE-assessed Vmax values in the aorta at the former coarctation site (r=0.90, n=16). Aliasing occurred in 13 patients. VEC-MR is a useful modality for assessing jet velocities in the follow-up of patients after aortic coarctation. Despite of aliasing, accurate velocity measurements up to two times VENC are possible using binary images.

[CT and MRI characteristics of tumours of the temporal bone and the cerebello-pontine angle].

ZusammenfassungTumoröse Veränderungen des Schläfenbeins und Kleinhirnbrückenwinkels sind selten. Diese Tumoren können in benigne und maligne Veränderungen eingeteilt werden.In dieser Arbeit sollen die CT- und MRT-Charakteristika der Tumoren des Schläfenbeins und Kleinhirnbrückenwinkels gezeigt werden. Die Computertomographie (HRCT) wird in axialer Schichtführung in der Auswertung mit hochauflösendem Knochenfenster durchgeführt. Die koronalen Schichten können aus dem axialen Datensatz rekonstruiert oder direkt in koronaler Ebene hergestellt werden.Mit der MRT kann zunächst mit einer FLAIR-Sequenz in axialer Ebene das gesamte Gehirn untersucht werden, um einen Tumoreinbruch nach intrakraniell auszuschließen oder nachzuweisen.Danach werden axiale T2-gewichtete Fast-(Turbo-) Spinechosequenzen oder fettunterdrückte Inversion-recovery-Sequenzen in hochauflösender Technik über die Schläfenbeinregion angefertigt, gefolgt von axialen T1-gewichteten Spinechosequenzen vor und nach Kontrastmittel-(KM-)Gabe in hochauflösender Technik.Zuletzt können koronale T1-gewichtete Spinechosequenzen in hochauflösender Technik mit Fettunterdrückung nach KM-Gabe über die Schläfenbeinregion durchgeführt werden.Die HRCT kann die knöcherne Ausdehnung und dazugehörige Knochenveränderungen darstellen, die MRT erfasst genau die Tumorausdehnung in den Weichteilen. Mit der HRCT und der MRT gemeinsam lässt sich die exakte Tumorausdehnung zur therapeutischen Planung bestimmen. Die HRCT zeigt die knöchernen Veränderungen ausgezeichnet. In Einzelfällen – wie z.B. bei Exstosen des äußeren Gehörgangs – kann es genügen, lediglich eine HRCT des Schläfenbeins durchzuführen.Aufgrund des Aggressivitätsverhaltens des Tumors in der HRCT sind auch Rückschlüsse auf einen eher benignen oder malignen Tumortyp möglich. Mit der MRT können aufgrund des sehr hohen Weichteilkontrastes auch manche Tumoren – insbesondere vaskuläre wie z.B. Glomustumoren – gewebemäßig charakterisiert und in eher benigne und maligne unterteilt werden.Somit sind die HRCT und die MRT des Schläfenbeins exzellente Methoden, um tumoröse Läsionen darzustellen und einzuordnen.Die Methoden sollten nicht als konkurrierend, sondern als komplementär betrachtet werden und haben u. U. einen großen Einfluss auf das therapeutische Vorgehen.AbstractTumours lesions of the temporal bone and of the cerebello-pontine angle are rare.This tumours can be separated into benign and malignant lesions. In this paper the CT and MRI characteristica of tumours of the temporal bone and the cerebello-pontane angle will be demonstrated. High resolution CT (HRCT) as usually performed in the axial plane are using a high resolution bone window level setting, coronal planes are the reconstructed from the axial data set or will be obtained directly. With the MRI FLAIR sequence in the axial plane the whole brain will be scanned either to depict or exclude a tumour invasion into the brain.After this,T2-weighted fast spin echo sequences or fatsuppressed inversion recovery sequences in high resolution technique in the axial plane will be obtained from the temporal bone and axial T1-weighted spinecho sequences before and after the intravenous application of contrast material will be obtained of this region. Finally T1-weighted spinecho sequences in high resolution technique with fatsuppression after the intravenous application of contrast material will be performed in the coronal plane. HRCT and MRI are both used to depict the most exact tumorous borders. HRCT excellently depicts the osseous changes for example exostosis of the external auditory canal, while also with HRCT osseous changes maybe characterized into more benign or malignant types. MRI has a very high soft tissue contrast and may therefore either characterize vascular space-occupying lesions for example glomus jugulare tumours or may differentiate between more benign or malignant lesions. In conclusion HRCT and MRI of the temporal bone are excellent methods to depict and mostly characterize tumour lesions and can help to differentiate between benign and malignant lesion.These imaging methods shall be used complementary and may have a great impact for the therapeutic planning.

Die klinische Anwendung der Densitometrie

ZusammenfassungEine frühe Diagnose der Osteoporose und eine akkurate Beurteilung von Behandlungserfolgen stehen im Mittelpunkt der radiologischen Bestrebungen. Die häufigsten klinisch angewendeten Methoden, um das periphere Skelett sowie das Achsensekelett zu beurteilen sind die 2-Spektren-Röntgenabsorptimetrie (DXA, ”dual x-ray absorptiometry”), die quantitative Computertomographie (QCT) and der quantitative Ultraschall (QUS). Generell werden die Meßergebnise eines Individuums mit einer alters-, geschlechts-, und rassenspezifischen Kontrollgruppen verglichen. In diesem Zusammenhang ist die Bestimmung der Knochenmasse ein Indikator des künftigen Frakturrisikos eines Patienten. Die radiologische Diagnose der Osteoporose kann durch die Bestimmung der Knochenmasse erfolgen, auch wenn keine prävalenten Frakturen vorliegen. Das Frakturrisiko für den Meßwert eines Individuums steigt um etwa das 1,5- bis 2,5fache für jede Standardabweichung (SD) unter der Spitzenknochenmasse der Normbevölkerung (T-Wert). Die Wahl des Meßortes und der Untersuchungstechnik zur Bestimmung der Knochenmasse oder des Frakturrisikos muß sich nach individuellen Gegebenheiten am Patienten sowie den Stärken und Limitationen der Technik richten.SummaryAn early diagnosis of osteoporosis and an accurate estimation of treatment outcome are the focus of the radiological efforts. The most commonly applied methods for the evaluation of the peripheral and axial skeleton are dual x-rax absorptiometry, quantitative computed tomography, and quantitative ultrasound. Data of an individual are generally compared to an age-, sex-, and ethically-matched control population. The bone mass measurement predict a patients future risk of fracture and the presence of osteoporosis can be diagnosed even in the absence of prevalent fractures. Fracture risk increases approximately 1.5–2.5 times for every 1.0 standard deviation an individual’s bone mass is below the mean peak mass of healthy young individuals (T-score). The choice of the appropriate measurement sites may vary depending on the specific circumstances of the patient. The choice of the appropriate technique in any given clinical circumstance should be based on the strength and limitations of the different techniques.

Automated vessel edge detection in velocity-encoded cine-MR (VEC-MR) flow measurements: a retrospective evaluation in critically ill patients.

OBJECTIVEnTo assess feasibility of automated edge detection in magnetic resonance (MR) flow calculations in a clinical setting with critically ill patients.nnnMATERIAL AND METHODSnVelocity encoded cine-MR (VEC-MR) flow measurements cross-sectional area (CSA), mean spatial velocity (MSV), instantaneous flow (IF), flow (F), 0.5 T Philips, TR 800-800, TE=8 ms, 30 degrees flip angle, FOV 280 mm, 128 x 256 matrix, temporal resolution 16 time frames/RR, VENC=120 cm/s) were obtained in 20 major thoracic human vessels (ascending aorta, main, right and left pulmonary artery-AAO, MPA, RPA, LPA) of five patients, suffering from severe chronic thromboembolic pulmonary hypertension (CTEPH). Flow maps were evaluated by two independent observers using conventional manual edge detection (INTER m/m). Flow calculations were performed by one observer using both, manual and automated edge detection (INTRA m/a), by a second observer using automated edge detection two times (INTRA a/a) and by two independent observers using automated edge detection (INTER a/a). Evaluation time was measured. Linear regression analysis and Students t-test were performed.nnnRESULTSnOverall regression coefficients (r2) for INTER m/m, INTRA m/a, INTER a/a and INTRA a/a, respectively, were as follows: CSA, 0.91, 0.91, 0.96, 0.98; MSV, 0.97, 0.99, 0.99, 0.99; IF, 0.98, 0.99, 0.99, 0.99; F, 0.98, 0.99, 0.99, 0.99. Manual CSA values differed significantly from automated data in MPA (P=0.01), RPA (P=0.0008) and LPA (P=0.02). No difference was found for the other assessed parameters of the pulmonary circulation. Average evaluation time per vessel was 20.2+/-2.6 min for manual and 2.1+/-0.7 min for automated edge detection (P<0.00001).nnnCONCLUSIONnThe software program used provided reproducible data, lead to a 90% reduction in evaluation and calculation time and, therefore, might excel the utilization of VEC-MR flow measurements. Despite variations in the evaluation of the pulmonary circulation CSAs, flow assessment is feasible in critically ill patients.

[Computed tomography and magnetic resonance imaging of acquired abnormalities of the inner ear and cerebello-pontine angle].

ZusammenfassungBei erworbenen Veränderungen des Innenohrs und der Kleinhirnbrückenwinkelregion zeigen CT und MRT typische Bildcharakteristika, wobei die Bildgebung der zu suchenden Veränderung angepasst werden sollte.Die CT liefert hochauflösend (HRCT) einen exzellenten Knochen-, die MRT einen hervorragenden Weichteilkontrast.Akute entzündliche Veränderungen sind in der HRCT nicht erkennbar, sondern nur in der kontrastmittelverstärkten MRT. Die HRCT erfasst am besten knöcherne Veränderungen wie Ossifikationen des membranösen Labyrinths im Rahmen einer chronischen Entzündung, otosklerotische und traumatische Veränderungen – selbst wenn diese nur diskret sind. Tumoröse Veränderungen, die zu keiner ossären Veränderung führen wie kleine Schwannome sowie posttraumatische Einblutungen im Innenohr und/oder Kleinhirnbrückenwinkel werden am besten mit der MRT dargestellt.Die MRT ist die Methode der Wahl, um tumoröse Veränderungen der Innenohrregion zu erfassen.Auch fibrotische Veränderungen im Labyrinth – nach einer akuten Labyrinthitis – können nur mit der MRT gezeigt werden.Somit kann zusammengefasst gesagt werden, dass die HRCT und die MRT je nach Einsatzgebiet exzellente Methoden sind,um erworbene Veränderungen in der Innenohr- und Kleinhirnbrückenwinkelregion abzuklären. Die HRCT erfasst am besten die knöchernen Veränderungen,während die MRT am besten Weichteilveränderungen erfasst, selbst wenn es sich um sehr diskrete Veränderungen handelt.Die HRCT und die MRT in hochauflösender Technik sind somit bei der Abklärung von erworbenen Prozessen der Innenohr- und Kleinhirnbrückenwinkelregion als komplementäre Methoden zu sehen.AbstractCT and MRI of acquired abnormalities of the inner ear and cerebello-pontine angle present themselves with very typical findings. The imaging should be adapted to the pathology looked for and either CT or MRI should be used alone or in combination.CT, especially high resolution CT (HRCT), provides an excellent bone contrast, while MRI has a much superior soft tissue contrast. Acute inflammatory changes of the inner ear are solely depicted by contrast-enhanced MRI.HRCT excellently depicts osseous changes of the inner ear and cerebellopontine angle such as chronic ossifying labyrinthitis occurring after acute labyrinthitis, otosclerotic or traumatic changes.Tumorous changes not yielding to bony changes are best delineated by MRI.Posttraumatic hemorrhage and chronic fibrotic changes within the labyrinth are depicted by MRI, only.In conclusion HRCT and MRI are excellent methods to delineate acquired abnormalities of the inner ear and cerebello-pontine angle. HRCT best depicts osseous changes while MRI best depicts soft tissue changes. HRCT and MRI are not concurrent methods but should better be used as complementary methods for imaging acquired abnormalities of inner ear and cerebellopontine angle.

Flachbilddetektorsysteme in der Skelettradiologie

ZusammenfassungDurch Aufstellung und komplette digitale Integration von Flachbild-(Festkörper-) Detektoren anstelle von Film-Folien- bzw. Phosphorspeicherplattensystemen kommt es in einer radiologischen Abteilung zu einer Straffung des Arbeitsablaufes.Unter Einsatz der Flachbilddetektorentechnologie reduziert sich der eigentliche Bilderzeugungsprozess (von Patientenlagerung bis zur Bildfertigstellung) um über 30%.Wesentliche Vorteile dieser Totalintegration von RIS,PACS und Flachbilddetektorsystem sind die enorm gesteigerte Qualität durch fehlende Verwechslungsmöglichkeit von Bild- und Befunddaten, leichteres Handling, da in 95% aller Fälle keine Kassetten verwendet werden, und die Möglichkeit zur Bildnachbearbeitung. Die diagnostische Qualität der Skelettbilder ist im Vergleich zu konventionellen Röntgenaufnahmen zumindest adäquat, in den meisten Fällen zeigen sich jedoch deutliche Verbesserungen der Beurteilungsparameter bei einer Erniedrigung der Strahlenexposition um 30–50%.In Anbetracht der zahlreichen Vorteile der digitalen Aufnahmetechniken wird die Flachbildradiographie trotz der bis jetzt deutlich höheren Beschaffungskosten mit sehr hoher Wahrscheinlichkeit die konventionellen Röntgenaufnahmen mittelfristig ersetzen können.AbstractImplementation of flat-panel detectors and digital integration of the technique instead of the use of conventional radiographs leads to a shortening of the work process.With flat-panel technology the image production process is shortened by more than 30%. Major advantages in the implementation of integrated RIS,PACS and flat-panel detector system are increases in quality because most mistakes in picture labeling can be avoided, easier handling without the need for cassettes, and the possibility of image post-processing. The diagnostic quality of the images in the field of musculoskeletal radiology is, in comparison to conventional radiographs, at least adequate and in most cases markedly improved with a marked reduction in radiation exposure of around 30–50%.With respect to the numerous advantages of the digital techniques and especially flat-panel technology there is a very high likelihood that conventional radiographs will be substituted in the coming years, even though the cost of the new technology is currently significantly higher compared to conventional systems.

'The Closer'-percutaneous vascular suture device: evaluation of safety and performance in neuroangiography

OBJECTIVEnTo evaluate the use of the suture mediated vascular closure device concerning practicability and safety in clinical angiography practice.nnnMATERIAL AND METHODSnOne hundred and seventeen patients (59 female, 58 male, mean age 40.9+/-13.4) underwent percutaneous closure of common femoral arterial puncture sites following diagnostic neuroangiography using the suture device the Closer (Perclose Inc., Redwood City, CA, USA). Primary success, early problems (within 24 h) and late complications were evaluated. Complications were graded as minor and severe with or without need of surgical intervention and categorized by type. Parameters such as age, gender, sheath size and number of previous arterial punctures were evaluated with respect to complications.nnnRESULTSnPercutaneous closure was primary successful in 85% (100/117). The overall complication rate was 32% (28% mild n=35, 4% severe n=6, which needed surgical intervention). All but one problem occurred within the first 24 h after the suture. Additional manual compression was necessary in 32 cases (25%). There was no significant difference in age and gender between the groups with and without complications. Sheath size was significantly larger (P<0.01) and numbers of preceeding angiograms were significantly higher (P<0.01) in the complications group compared with uncomplicated cases.nnnCONCLUSIONnThe evaluated percutaneous vascular suture device is useful in clinical practice but limitations concerning patient selection seem to emerge in order to avoid complications.