Assessment of organ dose and image quality in head and chest CT examinations: a phantom study.

The purpose of this study is to assess dose for radiosensitive organs and image quality in head and chest computed tomography (CT) examinations. Our focus was in the brain, eye lens and lung organs using two protocols; one protocol with fixed mAs and filtered back projection (FBP) and another with tube current modulation (TCM) and sinogram affirmed iterative reconstruction (SAFIRE). Measurements were performed on a 128-slice CT scanner by placing thermoluminescent dosimeters (TLDs) in an anthropomorphic adult phantom. Results were compared to a CT-Expo software. Objective image quality was assessed in terms of signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). SPSS software was used for data analyses. Results showed that, using TCM, doses were reduced by 22.84%-25.06% for brain, by 21.82%-23.48% for eye lens and by 54%-53.22% for lung with TLD and CT-Expo respectively. The increased SNR and CNR values achieved for scans performed with TCM combined with iterative reconstruction techniques were 38.68%-58.81% and 38.91%-43.60% respectively. We conclude that, using TCM, a significant mean organ dose reduction is achieved for brain, eye lens and lung organs. Then, combined with iterative reconstruction, image quality was well maintained in terms of SNR and CNR. Thus it is highly recommended in clinical practice optimization in head and chest CT examinations.

[Cervicobrachial neuralgia revealing neurosarcoma]. / Névralgie cervicobrachiale révélatrice d'un neurofibrosarcome (MPNST) cervical.

Malignant peripheral nerve sheath tumor (MPNST) or neurofibrosarcoma, previously described as malignant Schwannoma or neurosarcoma, is an extremely rare cause of malignancy localized in the neck. Half of reported cases occurred in patients with neurofibromatosis in Von Recklinghausen disease type I. Typical features include high grade malignancy and a tendency to recurrence and distant metastases. We report the case of a 56-year-old woman with neurosarcoma of the neck, which was revealed by a cervicobrachial neuralgia. The physical examination found a mass on the left side of the neck. Plain radiographs showed osteoarthritis. MRI showed a well-defined paravertebral mass. Pathologic diagnosis was neurosarcoma. Radiotherapy was delivered.

[Aneurysmal bone cyst of the ethmoid bone]. / Kyste osseux anévrismal de l'ethmoïde.

Aneurysmal bone cysts is a benign, slow growing expansile lesion usually found in long bones or vertebrae. Only 5 cases of ABC of the ethmoid bone have been reported in the literature. Plain radiographs are not specific. CT and MRI are very useful to depict the extent of the lesion and demonstrate the presence of blood-fluid levels, which is a characteristic finding of ABC. We present one atypical case of ABC of the ethmoid bone in a 15-year-old female characterised by its extensive involvement and its rare location.

[Bone hydatidosis. 12 cases]. / L'hydatidose osseuse. 12 cas.

The hydatic cyst is a parasitic disease caused by the development in man of the larval form of echinococcus granulosus. All parts of the body may be involved, but the liver and lungs are the main locations of the disease. The bone site is rare, accounting for 0.9 to 2% of all hydatic lesions. Between 1982 and 1988, we have compiled 12 cases of hydatic disease of bone. They were located in the skull (4 cases), the iliac bone (4 cases), the omoplate (1 case), the ribs (1 case), the femur (1 case) and the fibula (1 case). These lesions are generally considered as primary, but association with visceral locations was noted in 3 cases in our series.

[Splenic nodules and sickle cell anemia]. / Nodules spléniques et drépanocytose.

OBJECTIVE: We report 4 patients with sickle cell anemia presenting with intra-splenic benign nodules corresponding to islands of preserved tissue within splenic ferro-calcinosis. MATERIAL AND METHODS: Ultrasound, CT and MRI findings were evaluated and compared to a follow-up study by ultrasound and CT done after 6 to 12 months. RESULTS: Ultrasound showed multiple well-defined rounded nodules appearing hypoechoic compared to the rest of the spleen that was hyperechoic. On CT, the nodules were homogenous, hypodense relative to the spleen, isodense to the liver in 3 cases and hypodense to the liver in 1 case. On MRI, the nodules appeared relatively hyperintense within low-signal-intensity spleens. The ultrasound and CT follow-up study demonstrated no remarkable change. CONCLUSION: In sickle cell patients, intra-splenic benign nodules corresponding to normal splenic tissue may be identified on imaging studies. The differential diagnosis is discussed.

[Mondini's malformation. Apropos of a case]. / La malformation de Mondini. A propos d'un cas.

Mondini's malformation is a rare internal ear malformation. It's often discovered in childhood in the course of perception deafness check up, or repetitive meningitis in some other cases. The authors report a case of complex Mondini's malformation with fistulas of cerebro-spinal-fluid in oval and round windows, and stress the interest of high resolution computed tomography.

[Thrombophlebitis of the ovarian vein. Apropos of 2 cases]. / La thrombophlébite de la veine ovarienne. A propos de 2 cas.

Thrombophlebitis of the ovarian vein is a rare post-partum complication. Its diagnosis is said to be difficult, but was greatly facilitated by the progress made in imaging. The authors report about two cases identified with computed tomography. Evolution was favorable in both cases with an anticoagulant and antibiotic treatment.

[Septic thrombosis of the cavernous sinus complicating malignant staphylococcal infection of the face]. / La thrombose septique des sinus caverneux compliquant la staphylococcie maligne de la face.

Septic thrombosis of the cavernous sinuses most commonly follows staphylococcal infections of the middle third of the face. Orbital symptoms are constant. We report six cases diagnosed only by CT. At present, MR imaging is the diagnostic procedure of choice. Its findings are thought to reflect the septic nature of the thrombosis.

[A rare cause of multiple lacunae of the cranial vault and temporal bone in adults: histiocytosis X]. / Une cause rare de lacunes multiples de la voûte et de l'os temporal chez l'adulte: l'histiocytose X.

Histiocytosis X is an uncommon disease. Temporal bone involvement is a frequent head and neck manifestation. Most patients are under fifteen years of age. The authors report a case of a bilateral extensive temporal involvement complicated with vertigo and peripheric facial palsy. CT plays a dominant role in the diagnosis because of the ability to identify bone destruction, soft tissue involvement and intra-cranial histiocytosis more accurately.

[Pelvic hydatidosis in women. Apropos of 3 cases]. / L'hydatidose pelvienne chez la femme. A propos de 3 cas.

In 80 to 90% of cases, hydatid disease affects the liver and the lung. In only 2% of cases is it localised in the pelvis. On the clinical level there is no specific sign of pelvic hydatid disease. The diagnosis used to be difficult but it has become easy, thanks to modern methods of imaging. The authors report 3 cases that were diagnosed by ultrasound and tomodensitometry. Surgical removal, which was carried out in each case without difficulty, was successful. They review the ultrasound and tomodensitometry pictures of hydatid disease and the principles of its surgical treatment.

[Chylothorax caused by thrombosis of the superior vena cava in Behçet's disease]. / Chylothorax par thrombose de la veine cave supérieure au cours d'une maladie de Behçet.

The occurrence of chylothorax due to thrombosis of the subclavicular venous drainage is reported. This occurred in a young adult with previously undiagnosed Behçet's disease which had been developing over three years. Venous thromboses during the course of Behçet's disease are extremely frequent and are currently one of the diagnostic criteria. When these thromboses involve the central veins, in particularly the superior vena cava or one of its branches a chylothorax is possible due to blockage of the lymphatic circulation and may be a grave complication, given its location.

[Extramedullary hematopoiesis: multiple mediastinal localizations]. / Hématopoïèse extra-médullaire: localisations médiastinales multiples.

Intrathoracic extra-medullary hematopoiesis is a compensatory mechanism usually seen in thalassemia. The authors report a case with multiple mediastinal localisations fortuitously discovered. CT has allowed diagnosis and led percutaneous biopsy.

Dedifferentiated adamantinoma associated with fibrous dysplasia.

A 21-year-old patient presented with an aggressive lesion of the left tibia associated to lymph nodes and lung metastasis. Histological examination revealed a high grade spindle cell sarcoma involving some areas of cytokeratine positive cells. Ultrastructural examination showed the presence of epithelial features in the sarcomatoid cells. The diagnosis of dedifferentiated spindle-celled adamantinoma was established. A second lesion of the right tibia was diagnosed as fibrous dysplasia. The patient had a leg amputation. He died 2 years later with multiple lung and bone metastases. The diagnosis of dedifferentiated adamantinoma should be considered when a clinician is confronted with a tibial biopsy of a "keratin-positive sarcoma". The association with fibrous dysplasia in this case is discussed.

Bizarre Parosteal Osteochondromatous Proliferation: Nora's Lesion.

The purpose of this study was to review the imaging and anatomopathologic findings and to discuss the main differential diagnosis of bizarre parosteal osteochondromatous proliferation (BPOP) or Nora's lesion, a rare benign surface lesion of the bone. Histologically confirmed plain radiographs, ultrasound, CT and MRI images of four patients with BPOP were obtained and retrospectively reviewed. Three cases involving the hand and one involving the foot are reported. On plain radiographs, BPOP is a wellmarginated, calcified or ossified mass arising directly from the cortical surface of the underlying bone. Ultrasound images show a low echoic peripheral cap around the lesion. CT images show the wide base of the lesion. On MRI, BPOP was of a low signal on T1, enhancing following gadolinium administration. Underlying bone and adjacent surrounding soft tissues were normal.

[Intraperitoneal vascular emergencies]. / Urgences vasculaires intrapéritonéales.

Intraperitoneal vascular lesions constitute severe causes of acute abdomen. These disorders include ischemia and infarction of colon and small bowel and abdominal hemorrhage. In case of intestinal ischemia, the radiologic procedures are performed in order to establish the diagnostic, identify the site of ischemia, and detect the etiology of ischemia. Plain radiography of the abdomen, ultrasonography, CT scan and angiography may be performed. In case of intestinal hemorrhage, angiography may be performed when endoscopy fails to establish the diagnosis. Embolization can be performed in selected cases.