Thorsten Leibecke

Radiation Dose to the Radiologist's Hand During Continuous CT Fluoroscopy-Guided Interventions

Computed tomography fluoroscopy (CT fluoroscopy) enables real-time image control over the entire body with high geometric accuracy and, for the most part, without significant interfering artifacts, resulting in increased target accuracy, reduced intervention times, and improved biopsy specimens [1–4]. Depending on the procedure being used, higher radiation doses than in conventional CT-supported interventions might occur. Because the radiologist is present in the CT room during the intervention, he is exposed to additional radiation, which is an important aspect. Initial experience with CT fluoroscopically guided interventions is from the work of Katada et al. in 1994 [5] and only relatively few reports on radiation aspects in CT fluoroscopy are found in the literature [1, 2, 6–11]. To date, there are no reported injuries to patients and radiologists occurring with CT fluoroscopy. The time interval since the wide use of CT fluoroscopy is too short to have data on late effects to the operator using CT fluoroscopy on a daily basis. In addition, the spectrum of CT fluoroscopically guided interventional procedures will expand and more sophisticated procedures requiring longer fluoroscopy times will be performed. Thus, effective exposure reduction is very important. The purpose of our study was to assess the radiation dose to the operator’s hand by using data from phantom measurements. In addition, we investigated the effect of a lead drape on the phantom surface adjacent to the scanning plane, the use of thin radiation protective gloves, and the use of different needle holders.

Magnetic resonance imaging and correlative gross anatomy of the ligamentum semicirculare humeri (rotator cable).

The purpose of this study has been to demonstrate macroscopic and MRI anatomy of the so‐called rotator cable, otherwise known as the ligamentum semicirculare humeri (LSCH) of the superior shoulder joint capsule. Twelve shoulder joints from eight cadavers were dissected; seven of which, from four of the cadavers, were studied using MR arthrography (1.5‐Tesla device Somatom Symphony®, Siemens, Erlangen, Germany) prior to dissection. The MRI protocol included T1WI, PDWI, and DESS 3D WI standard sequences. The results of MRI were compared with gross anatomic dissection findings. The macroscopically recognizable capsular bundle of LSCH fibers was identified by anatomic dissection in all specimens. On MRI, the entire ligament or parts of it could be identified in six of seven cases. It was best visualized on axial images. In the evaluation of magnetic resonance images of superior shoulder joint structures, additional knowledge on the anatomy of the LSCH can be used by the radiologist to facilitate detailed interpretation of the shoulder MRI. Clin. Anat. 21:420–426, 2008.

The anterior glenohumeral joint capsule: macroscopic and MRI anatomy of the fasciculus obliquus or so-called ligamentum glenohumerale spirale

The purpose of this study was to demonstrate the macroscopic and MRI anatomy of the fasciculus obliquus, otherwise known as the ligamentum glenohumerale spirale or spiral GHL of the anterior shoulder joint capsule. Conventional and MR arthrography (1.5-T device Somatom Symphony, Siemens with shoulder coil) images in standard planes were compared with gross anatomic dissection findings in six fresh shoulder specimens from three cadavers. The MR imaging protocol included T1, PD and DESS 3D WI sequences. The macroscopically recognisable band—the spiral GHL—was identified by anatomic dissection and MRI in all the specimens. It was best visualised by MR arthrography on axial and oblique sagittal planes (T1; PD WI) and appeared as a low signal intensity stripe within the superficial layer of the anterior joint capsule. The absence of the variable middle glenohumeral ligament did not influence the anatomic properties and the MR imaging of the spiral GHL. Diagnostic visualisation of the normal anatomic structures is a prerequisite to distinguish between normal and pathologic conditions. Anatomy of the spiral GHL can be used by radiologists for more detailed interpretation of the anterior shoulder joint capsule ligaments on MR images.

Tumorablation der Leber

ZusammenfassungMinimal-invasive Verfahren zur Ablation primärer und sekundärer Lebertumoren gewinnen zunehmend an klinischer Bedeutung. Dies gilt insbesondere vor dem Hintergrund, dass die chirurgische Resektion und Chemotherapien nur bei einer limitierten Anzahl von Patienten anwendbar bzw. nur von begrenztem Erfolg sind.Die lokalen tumorablativen Verfahren umfassen chemo- (perkutane Alkoholinstillation, transarterielle Chemoembolisation), thermo- (Radiofrequenz-, Laser-, Mikrowellen-, Kryoablation, hochintensiver fokussierter Ultraschall) und radioablative Verfahren (interstitielle Brachytherapie, selektive interne Radiotherapie). Die Methoden unterscheiden sich in der Durchführung und Wirkweise zum Teil erheblich, allen gemeinsam ist—bei korrekter Anwendung—die hohe therapeutische Effizienz bei gleichzeitig niedriger Komplikationsrate. Die Kenntnis spezifischer Indikationen und Kontraindikationen ist entscheidend, diese Methoden sinnvoll in multimodale Therapiekonzepte einzubringen.AbstractMinimal-invasive techniques for ablation of primary and secondary hepatic tumors gain increasingly clinical importance. This is especially true since surgical resection and classic chemotherapy is successful only in a limited number of patients.Local ablative methods incorporate chemo- (percutaneous alcohol instillation, transarterial chemoembolization), thermo- (radiofrequency-, laser-, microwave-, cryoablation, high intensive focused ultrasound) and radio-ablative techniques (interstitial brachytherapy, selective internal radiotherapy). Regarding their implementation and specific effects these methods are varying widely, nevertheless all of them have a high therapeutical efficacy together with a low complication rate in common—correct application presumed. The knowledge on specific indications and contraindications is crucial to implement these methods into multimodality therapy concepts.

Reply to the Editor-in-Chief

Sir: Thank you for giving us the opportunity to clarify an issue that is very important to us. Regarding our recent publications [1, 2], there has been concern over violation of commonly accepted ethical rules of scientific writing, namely reuse of already published material. We never had the intention of increasing the number of our publications by publishing the same data twice. In the process of manuscript preparation, we realised that it would be impossible to adequately deal with all the different aspects of the study in a single paper. We were also confronted with the fact that it would breach the German laws on animal protection to carry out redundant animal experiments in order to generate completely new data sets for a second publication. Our article in Intensive Care Medicine (ICM) was conceptually designed as a medical research paper comparing electrical impedance tomography (EIT) and computer tomography analysis in an animal model. The article by Luepschen et al., submitted to Physiological Measurement (PM) about 4 weeks later (for publication in a congress supplement), is primarily a technical article for a rather technically oriented readership, discussing the suitability of EIT measurements for use in automated protective ventilation procedures such as the Open Lung Concept. A major goal of the PM study was to derive new mathematical features from EIT measurements for eventual use as process variables for an automated closed-loop controller. As is common practice in the engineering community, we reused some of the raw data of the ICM paper to develop new algorithms and to test their suitability and efficiency. The salient mathematical feature of the PM article is the dynamic centre of gravity index ycog, which is neither shown nor discussed in the ICM article. To illustrate this index, we included a partly overlapping illustration in the PM article, i.e. the tidal volume and PaO2 curve of Fig. 3 in ICM. We regret that we did not precisely follow the “Uniform Requirements for Manuscripts Submitted to Biomedical Journals: Writing and Editing for Biomedical Publication”, published by the International Committee of Medical Journal Editors (www.ICMJE.org), by not informing the editors of PM and ICM that the two papers partly used the same data base. It has also been criticised that the PM paper includes no mention of the ICM paper. The reason for this is that during the editorial process we were asked by the editorial office of PM to update the reference to the ICM article. We then dropped the reference, because a major revision of the ICM article was still pending. We nevertheless apologise for not having referenced the PM article in the final edit of the ICM paper. In conclusion, the two papers address different aspects of the topic aimed at different readerships and, hence, result in different deductions that do not contradict but rather complement each other. Thus, we believe that there is no substantial overlap between the two papers, so that in our view they cannot be regarded as selfplagiarism resulting in a duplicate or redundant publication.

Reply to the comment by Dr. Borges

Sir: First of all, we want to thank Dr. Borges for mentioning some important points regarding the problem of alveolar gas absorption and assessment of pulmonary recruitment. One of the points of Dr. Borges’ criticism is the design of the positive end-expiratory pressure (PEEP) trial in our study. We never denied, and now fully confirm, the statement that only a decremental PEEP titration after a recruitment maneuver (RM) can determine the lung specific closing pressure. However, we do not think it can be advocated, on the basis of recent experimental and clinical data, that a special PEEP trial will lead to a better outcome in ventilated patients. Our RM abandoned high airway pressure periods, in contrast to the maneuver favored by Borges et al. [1]. The use of such high airway pressure requires additional fluid therapies and administration of higher levels of catecholamines. The consequences of this intensive supplemental therapy have not been sufficiently explored and it could potentially lead to a higher mortality rate in patients with ARDS, and presumably in our animal model. Furthermore, our RM also opened the lung sufficiently, because a PaO2/FiO2 of 500 mmHg could be achieved in our animals – equivalent, according to Borges et al. [1], to nearly 0% of collapsed lung mass. It is generally accepted that different factors play a role in the development of lung collapse after a RM in ARDS: decrease of transpulmonary pressure, deterioration of surfactant function, gas absorption, and fluid filling of alveoli [2]. Hence, Dr. Borges’ argument that the duration of each decremental PEEP level is too short, solely because of the ongoing process of absorption of oxygen, might not hold for our acute lung injury model. Because this phenomenon is also dependent on the individual size of the gas pockets and the fluid filling of the alveoli, it is difficult to predict the optimal time of equilibration for the process to stop, particularly in lungs with high PEEP. Recently it was shown in patients with acute lung injury that high PEEP can prevent absorption atelectasis [3]. To minimize alveolar gas absorption, FiO2 concentrations have to be reduced and low Va/Q areas have to be avoided. In lungs which can easily be recruited, as in our lavage-induced model, a decrease of intrapulmonary shunt after a RM is established and will minimize the problem of gas absorption. Additionally, the 2-min duration was sufficient to achieve a stationary curve of relative impedance change. Furthermore, Dr. Borges advised using the ratio between mass of atelectatic tissue and total lung mass for the prediction of recruitment. We agree that this is the common calculation used by Gattinoni et al. [4] to measure recruitment in CT. Nevertheless, the objective of our study was to clarify whether EIT is able to evaluate the amount of functional regional recruitment during a PEEP trial. Because EIT is not able to directly detect pulmonary tissue mass, we decided to mainly compare the EIT measurement with the tidal volume calculation from CT, similar to Victorino et al. [5]. The increase of global and regional tidal volumes in pressure-controlled ventilation in our study can be defined as reflecting previously occurring functional recruitment. These EITand CT-based tidal volumes showed comparable behavior in most of our analyses; therefore, we cannot assent to Dr Borges’ statement that our methods underestimate functional derecruitment. To really find the “best protective PEEP”, also dynamic regional lung perfusion to estimate overdistension has to be measured, and until this measurement is available it cannot be claimed that PEEP was underoptimized.