Accelerated 3D echo-planar spectroscopic imaging at 4 Tesla using modified blipped phase-encoding.

Whole-brain echo-planar spectroscopic imaging (EPSI) often substantially lengthens MRI/MRSI (magnetic resonance spectroscopic imaging) protocols. To halve acquisition time, application of a blipped phase-encoding (PE) gradient during the EPSI readout (RO) was previously suggested by PE of the even RO echoes in k-space at an interstitial location along k(PE), separated from the odd RO echoes, effectively reducing the number of PEs by a factor of 2. However, the approach is very susceptible to phase inconsistencies between even and odd RO echoes in the presence of B(0) inhomogeneities and gradient imbalance, leading to ghosting in the PE direction. In this work, the blipped PE gradient is placed in between pairs of even/odd RO gradient lobes to avoid these problems. This approach is demonstrated in a phantom and in normal human brain in vivo at 4T. While the proposed method allows substantial reduction in metabolite ghosting, it may be limited by the presence of a relatively large spurious signal at the Nyquist frequency.     

Synthesis procedure for routine production of 2-[18F]fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[18F]F-A-85380).

2-[18F]Fluoro-3-(2(S)-azetidinylmethoxy)pyridine (2-[18F]F-A-85380) was among the first subtype selective radioligands to visualise the in vivo distribution of alpha4beta2-containing neuronal nicotinic acetylcholine receptors (nAChRs) in human brain. We developed a one-pot synthesis for the preparation of 2-[18F]F-A-85380 in a commercially available TRACERlab FXF-N synthesis module. The synthesis comprises a nucleophilic substitution followed by hydrolysis of a t-butyloxycarbonyl (BOC)-protected intermediate. After formulation for intravenous application up to 20 G Bq 2-[18F]F-A-85380 were produced from a starting activity of 100 G Bq [18F]fluoride in 60 min with a specific activity of about 4.10(5)GBq/mmol and a mean radiochemical purity of more than 99%.     

Manubriotomy versus median sternotomy in thymectomy for myasthenia gravis. Evaluation of the pulmonary status.

OBJECTIVE: In a prospective study, the effect of thymectomy on the pulmonary status of 50 consecutive patients with myasthenia gravis was evaluated over a time range of 4 years in the Chest and Chest surgery departments in the Cairo University Clinics and Thoracic Surgery Department of the Evangelisches Krankenhaus Duisburg-Nord. METHODS: The patients were divided into two groups: Group I included 26 patients who underwent thymectomy through median sternotomy. The mean age of the patients in this group was 24.8+/-10.5 (5-41) years. They were 19 females and seven males. Thirteen of the patients were in Myasthenia Gravis Foundation of America (MGFA) class IIa, and 12 were in class IIb, and one was in class IIIa. Group II included 24 patients who underwent thymectomy through manubriotomy. The mean age of the patients in this group was 25.2+/-9.2 (12-41) years. They were 13 females and 11 males. Eight of the patients were in MGFA class 2a, 14 were in class IIb, and two were in class IIIa. RESULTS: When compared to group I in which postoperative ventilation was required in 15.4% of patients, postoperative ventilation was not necessary in patients of group II with a statistically significant difference (P=0.04). The mean duration of stay in the intensive care unit was 111.4h in group II, and 169.7h in group I (P=0.03). The peak inspiratory flow rate and the forced vital capacity were also statistically significantly better in group II. There was no mortality in both groups, and the morbidity was higher in the median sternotomy group. CONCLUSION: Thymectomy through a manubriotomy, which allows extensive removal of ectopic thymic tissue in addition to the thymus through a less invasive approach than a full median sternotomy, is associated with a significantly smoother postoperative course and less pulmonary complications, when compared with thymectomy through a full median sternotomy.     

Laparoscopic management of a ruptured giant epidermoid splenic cyst.

BACKGROUND: Epidermoid splenic cysts are uncommon lesions of the spleen. They are known to become symptomatic as a consequence of enlargement, infection, or rupture, the latter being an exceedingly rare complication traditionally treated with open splenectomy. We herein report a unique case of a giant epidermoid splenic cyst that ruptured spontaneously and was successfully treated with the laparoscopic approach. CONCLUSION: Laparoscopic surgery may be considered an initial treatment option in cases of very large epidermoid cysts even when rupture occurs.     

Computer-assisted LISS plate osteosynthesis of proximal tibia fractures: feasibility study and first clinical results.

Fluoroscopy is the most common tool for the intraoperative control of long-bone fracture reduction. Limitations of this technology include high radiation exposure for the patient and the surgical team, limited visual field, distorted images, and cumbersome verification of image updating. Fluoroscopy-based navigation systems partially address these limitations by allowing fluoroscopic images to be used for real-time surgical localization and instrument tracking. Existing fluoroscopy-based navigation systems are still limited as far as the virtual representation of true surgical reality is concerned. This article, for the first time, presents a reality-enhanced virtual fluoroscopy with radiation-free updates of in situ surgical fluoroscopic images to control metaphyseal fracture reduction. A virtual fluoroscopy is created using the projection properties of the fluoroscope; it allows the display of detailed three-dimensional (3D) geometric models of surgical tools and implants superimposed on the X-ray images. Starting from multiple registered fluoroscopy images, a virtual 3D cylinder model for each principal bone fragment is constructed. This spatial cylinder model not only supplies a 3D image of the fracture, but also allows effective fragment projection recovery from the fluoroscopic images and enables radiation-free updates of in situ surgical fluoroscopic images by non-linear interpolation and warping algorithms. Initial clinical experience was gained during four tibia fracture fixations that were treated by LISS (Less Invasive Stabilization System) osteosynthesis. In the cases operated on, after primary image acquisition, the image intensifier was replaced by the virtual reality system. In all cases, the procedure including fracture reduction and LISS osteosynthesis was performed entirely in virtual reality. A significant disadvantage was the unfamiliar operation of this prototype software and the need for an additional operator for the navigation system.     

Sentinel Bleeding After Pancreaticoduodenectomy: A Disregarded Sign

Introduction Delayed massive hemorrhage induced by pancreatic fistula after pancreaticoduodenectomy is a rare but life-threatening complication. The purpose of this study was to analyze the clinical course of patients with late hemorrhage, with or without sentinel bleeding, to better define treatment options in the future. Material and Methods From April 1998 to December 2006, 189 pancreaticoduodenectomies were performed. Eleven patients, including two patients referred from other hospitals, were treated with delayed massive hemorrhage occurring 5 days or more after pancreaticoduodenectomy. Sentinel bleeding was defined as minor blood loss via surgical drains or the gastrointestinal tract with an asymptomatic interval until development of hemorrhagic shock. The clinical data of patients with bleeding episodes were analyzed retrospectively. Results Eight of the 11 patients had sentinel bleeding, and seven of them had it at least 6 h before acute deterioration. Seven out of 11 patients died, five out of eight with sentinel bleeding. No differences could be detected between patients with or without sentinel bleeding before delayed massive hemorrhage. The only difference found was that non-surviving patients were significantly older than surviving patients. Delayed massive hemorrhage is a common cause of death after pancreaticoduodenostomy complicated by pancreatic fistula formation. The observation of sentinel bleeding should lead to emergency angiography and dependent from the result to emergency relaparotomy to increase the likelihood of survival.     

18F-FDG PET for mediastinal staging of lung cancer: which SUV threshold makes sense?

(18)F-FDG PET is the most accurate noninvasive modality for staging mediastinal lymph nodes in lung cancer. Besides using visual image interpretation, some institutions use standardized uptake value (SUV) measurements in lymph nodes. Mostly, an SUV of 2.5 is used as the cutoff, but this choice was never deduced from respective studies. Receiver operating characteristic (ROC) analyses demonstrated that SUV thresholds of more than 4 resulted in the highest accuracy. But these high cutoffs imply high false-negative rates (FNRs). The aim of our evaluation was to determine an optimal SUV threshold and to compare its diagnostic performance with the results of visual interpretation. METHODS: This retrospective study included 95 patients with suspected lung cancer who underwent mediastinoscopy/mediastinal lymphadenectomy after (18)F-FDG PET (90-150 min after 250 MBq of (18)F-FDG). Maximum SUV was measured in 371 lymph node regions biopsied afterward and visually interpreted using a 6-level score (- - - through + + +). Diagnostic performance was assessed by ROC analysis. FNR and false-positive rate (FPR), the sum of both error rates (FNR + FPR), and diagnostic accuracy were plotted against a hypothetical SUV threshold to determine the optimum SUV threshold. RESULTS: SUVs in metastatic lymph nodes were higher (mean +/- SD, 7.1 +/- 4.5; range, 1.4-26.9; n = 70) than in tumor-free lymph node stations (2.4 +/- 1.7; range, 0.6-14.9; n = 301; P < 0.01). Inflammatory lymph nodes exhibited slightly increased SUVs (2.7 +/- 2.0; range, 0.8-14.9; n = 146). The plot of error rates featured a minimum of the sum FNR + FPR for an SUV of 2.5. With increasing SUV threshold, the FPR decreased most prominently up to that value whereas a continuous rise of FNR was noticed. Highest diagnostic accuracy was achieved with an SUV of 4.5. The areas under the ROC curves demonstrated that visual interpretation tends to be more accurate than SUV quantification (visual, 0.930 +/- 0.022; SUV, 0.899 +/- 0.025; P = 0.241). Using an SUV of 2.5 as the threshold, the resulting sensitivity, specificity, and negative predictive value were 89%, 84%, and 96%, respectively. CONCLUSION: For mediastinal staging, the choice of an SUV of 2.5 as the threshold is justified because FNR + FPR is minimized. The resulting high negative predictive value of 96% allows the omission of mediastinoscopy in patients with negative mediastinal findings on (18)F-FDG PET images. For the experienced observer, visual analysis should be relied on primarily, with calculation of the SUV used, at most, as a secondary aid. For the less experienced observer, the SUV may be of greater value.