Motion compensation for PET image reconstruction using deformable tetrahedral meshes.

Respiratory-induced organ motion is a technical challenge to PET imaging. This motion induces displacements and deformation of the organs tissues, which need to be taken into account when reconstructing the spatial radiation activity. Classical image-based methods that describe motion using deformable image registration (DIR) algorithms cannot fully take into account the non-reproducibility of the respiratory internal organ motion nor the tissue volume variations that occur during breathing. In order to overcome these limitations, various biomechanical models of the respiratory system have been developed in the past decade as an alternative to DIR approaches. In this paper, we describe a new method of correcting motion artefacts in PET image reconstruction adapted to motion estimation models such as those based on the finite element method. In contrast with the DIR-based approaches, the radiation activity was reconstructed on deforming tetrahedral meshes. For this, we have re-formulated the tomographic reconstruction problem by introducing a time-dependent system matrix based calculated using tetrahedral meshes instead of voxelized images. The MLEM algorithm was chosen as the reconstruction method. The simulations performed in this study show that the motion compensated reconstruction based on tetrahedral deformable meshes has the capability to correct motion artefacts. Results demonstrate that, in the case of complex deformations, when large volume variations occur, the developed tetrahedral based method is more appropriate than the classical DIR-based one. This method can be used, together with biomechanical models controlled by external surrogates, to correct motion artefacts in PET images and thus reducing the need for additional internal imaging during the acquisition.

Synchronous carcinoma of the ascending colon and caecum.

The caecum and the ascending colon are the colon segments most frequently affected by tumoral synchronism. Synchronous colorectal carcinoma etiopathogenesis is complex and most likely by malignancy of preexisting adenomas (adenoma-adenocarcinoma sequence). The following tumoral synchronism clinical case's particularity is represented by the simultaneous diagnosis of a flat-type adenocarcinoma of the caecum (less common histopathological type) and of a mucinous adenocarcinoma on the ascending colon. Tumor profiles of both carcinomas were examined histologically and immunohistochemically, emphasizing: (1) tumor proliferation different histological type; (2) residual adenomas in the periphery of the flat-type adenocarcinoma; (3) hardly microscopic detectable invasive character of the flat-type carcinoma; (4) mucinous carcinoma's infiltrating character and its immunohistochemical phenotype; (5) both tumor aggressiveness.

[Gastrointestinal stromal tumor in the cecum--a rare cause of ileo-cecal-colic invagination]. / Tumora stromala gastrointestinala (GIST) cu localizare cecala--cauza rara de invaginatie ileo-ceco-colica.

The gastrointestinal stromal tumors (GIST) are the rares mesenchymal tumors of the gastrointestinal tract (1-3% of all gastrointestinal neoplasias). The frequency of their location on the rectocolic site is quoted with the values lower than 10% of all GIST. The authors present a patient case 55 years aged, who presented a gastrointestinal stromal tumor cecal located. This tumor determined the invagination of the cec into the ascendent colon and then into transverse colon drawing the last ileal ansa and leading to an ileo-cecal-colic invagination, without development of a occlusive syndrome. We performed a computed tomography and an irigography. These investigations showed the complications of the case, but it could not find out a cause of the invagination. We discuss in our article the problem regarding find out the type of the tumor and its origin too. We also discuss about the therapy, etiopathogeny, evolution and prognosis of the GIST.

The immunohistochemical profile of the adenocarcinoma of upper gastric pole.

Although gastric adenocarcinoma continue to be the second continues to be the second cause of death worldwide, its incidence and mortality appear to have decreased in recent decades. Despite this decline, adenocarcinomas from proximal stomach tend to be more frequent during the last three decade. Adenocarcinomas with this location it seems that are a different, specific subtype of gastric carcinoma. The purpose of this study was to clarify the differences between gastric adenocarcinomas from upper and distal gastric pole using the immunohistochemistry. For this reason, we investigate histopathological and immunohistochemically 77 cases of upper gastric pole adenocarcinoma selected from a number of 472 gastric tumors. The immunohistochemistry was performing only in 32 cases by ABC technique with the following primary antibodies: Cytokeratin 7, Cytokeratin 19, Epithelial Membrane Antigen (EMA), Carcinoembryonic Antigen (CEA), Lysozyme, Vimentin, p53 protein, CD34 and Ki67 antigen. The acquired results do not distinguish a peculiar immunohistochemically profile unlike distal gastric adenocarcinomas. Nevertheless, we pointed out the predominance of diffuse adenocarcinomas type according to Laurens classification, which immunohistochemically were strong positive to cytokeratins, EMA, CEA and lysozyme. Moreover, investigation of some antigens likes lysozyme, p53, Ki67 and CD34 seems to be useful for prognostic estimation of carcinoma with this topography.

Intussusception of efferent intragastric loop after gastrojejunostomy--an exceptional cause of high occlusion and hematemesis.

Jejunogastric intussusception (GI) is an extremely rare complication of gastrojejunostomy (GJS) that may appear any time after surgical intervention. Less than 200 cases have been reported so far, on very small series. Young female, 32, who 12 years ago was operated for a gastroduodenal disease that she doesn't know many details about. She presented severe pain in the superior abdominal segment posteriorly irradiated, incoercible biliary nausea followed by hematemesis. The endoscopic, imaging and biological explorations suggested a huge gastric tumor that occupied the whole stomach and was bleeding diffusely. The rapid acute evolution asked for the urgent laparotomy that emphasized: soft tumour mass, intragastrically mobile without any scar at the stomach or duodenum level; adherent to the posterior of the stomach we discovered a ball of jejunal loops that couldn't be undone. The anterior gastrotomy sets the diagnosis: JGI of the efferent loops of a GJS. We hardly managed to reduce the intussusception, without resection, the loop being absolutely viable. In order to prevent a relapse, and because the anastomosis was not justified it was taken down. JGI in a patient presenting GJS must be taken into consideration in the presence of epigastric pain that would not cease, biliary nausea followed by hematemesis and rapid deterioration of general health status.

[A rare cause of upper digestive tract bleeding--pancreatic papillary adenocarcinoma]. / Hemoragie digestiva superioara de cauza rara--adenocarcinom papilifer pancreatic.

Authors present a rare case of upper digestive bleeding, the etiology of which is represented by a pancreatic papillary adenocarcinoma placed in the body and tail of the pancreas, with bleeding through the Oddi's sphincter, which causes difficult problems of medical and surgical diagnosis and treatment. The patient was known with acute cholecysto-pancreatitis of lithiasic cause, which has been surgically cured in 1977, being under treatment in the last years for the pancreatic injury which had been chronic pancreatitis and for hyperglycemia. The laboratory explorations emphasized a severe anaemia which was identified through upper digestive endoscopy (intermittent active bleeding from the major papilla) confirmed by echo and CT exam (heterogeneously body tissue of 10/8 cm diameter, involving the body and the tail of the pancreas). The medical treatment was complex, including proteic, hematologic, acido-basic, balance of hyperglycemia, and was followed by the surgical intervention consisting in body and tail pancreatico-splenectomy, followed by a postsurgical abscess, which required drainage. The surgical evolution was favorable. 6 months after leaving the hospital, the patient was admitted to medical diseases clinic with the diagnosis of deep right ileofemoral thrombophlebitis, duodenal acute ulcer and acute pneumonia of average right lobe, causing difficult problems of medical treatment. On this pathologic background, the diabetic failure also appears and the echo exam showing multiple secondary hepatic and peritoneal metastatic determinations. In medical literature we only met 13 similar communications, problems of diagnosis and treatment being very much alike to those presented.

[Upper digestive tract bleeding from ulcer with unusual etiology]. / Hemoragie digestiva superioara de etiologie ulceroasa cu sursa rara.

Case report of 40 year old female, admitted in emergency because signs and symptoms of upper digestive tract bleeding. Reappearance of bleeding, during haemodynamic compensation and dramatic installation of a haemorrhagic shock determines the surgical intervention for haemostasis. During surgery we discovered a duodenal ulcer with hypertrophic vessels, penetrating the gallbladder, that in its clinical course eroded the cystic artery. We performed bipolar cholecystectomy; removed the duodenal ulcer with anterior pilorectomy, Burlui antro-duodenostomy with a favorable postoperative course.

[Retroperitoneal Castleman's disease]. / Boala castleman retroperitoneala.

We present 2 cases of retroperitoneal localisation of Castleman's disease--hyalino-vascular histologic type. A 65 years old woman and a 67 years old man were admitted with the diagnosis of retroperitoneal tumour. The clinical findings were not specific. Surgical removal of the tumour is the treatment of choice. Focal recurrences didn't occur.

[Transhiatal esophagectomy]. / Esofagectomiile transhiatale.

Between 1991-2001, 40 patients underwent esophagectomy without thoracotomy for: caustic esophageal stenosis (26 cases), cervical esophageal cancer (1), lower esophageal cancer (7), and acute post-caustic oesophagitis (2). Thirty-four patients underwent transhiatal esophagectomy, 3 patients had an esophagectomy by "stripping" and in 3 other patients a combination of stripping and transhiatal esophagectomy. Postoperative complications included: injuries of the laryngeal recurrent nerve (2), pulmonary complications (13), anastomotic leakage (5). Two patients died in the postoperative period one from a myocardial infarction and the other from an acute myocardial dilatation. Trans-hiatal esophagectomy can be considered as a viable alternative to transthoracic esophagectomy in the management of the benign and malignant diseases of the esophagus. Transhiatal esophagectomy is a safe method of resection because of its reported lower morbidity and mortality and similar survival rates compared to transthoracic esophagectomy.