Inferiorly located retrobulbar hydatid cyst: CT and MRI features.

Orbital hydatid cyst is rare. Hydatid cysts in other organ systems are not mentioned in the previous papers emphasizing an orbital hydatid. Four cases of inferiorly located retrobulbar hydatid cysts have been reported previously. We present a rare inferiorly located retrobulbar hydatid cyst case in a Turkish child that also had multiple hydatid lesions in the lungs and the liver. We present the orbital CT and MRI findings. Preoperative diagnosis is important to avoid cyst rupture. Although hydatid disease is prevalent in South America, Australasia, the Middle East and Mediterranean countries, increased travel-isolated cases can be seen anywhere in the world.

Klippel-Feil syndrome in association with posterior fossa suboccipital dermoid cyst.

We present the second case of Klippel-Feil syndrome in association with a posterior fossa dermoid cyst extending through the occipital bone and presenting as a suboccipital subcutaneous mass. We describe its radiographic, CT, and MRI appearances as well as on MRI diffusion-weighted images. Posterior cranial fossa dermoid cysts and sinuses should be added to the list of congenital abnormalities which must be sought in patients with Klippel-Feil syndrome. Diffusion-weighted images of brain may differentiate these masses from cerebral spinal fluid collections.

The thyroid and parathyroid glands. CT and MR imaging and correlation with pathology and clinical findings.

Thyroid imaging approach is based on the preliminary clinical evaluation. Lesions that are smaller than 2 cm should be assessed with US, which is capable of discriminating masses as small as 2 mm and distinguishing solid from cystic nodules. US-guided FNAB provides tissue for cytologic examination of thyroid nodules. CT and MR imaging are indicated for larger tumors (greater than 3 cm diameter) that extend outside the gland to adjoining structures, including the mediastinum, and retropharyngeal region. Metastatic lymph nodes in the neck and invasion of the aerodigestive tract are also in the realm of CT and MR imaging. Thyroid nodules are categorized on scintigraphy as hot or cold nodules. Hot nodules are rarely malignant, whereas cold nodules have an incidence of 10% to 20% of malignancy. Calcifications (amorphous, globular, nodular, and linear) occur in adenomas and carcinomas and have no differential diagnostic features except for psammomatous calcifications, which are a pathognomonic finding in papillary carcinomas and a small percentage of medullary carcinomas. Papillary carcinoma is the most common malignant tumor (80%) followed by follicular (20% to 25%); medullary (5%); undifferentiated; anaplastic carcinomas (< 5%); lymphoma (5%); and metastases. Lymph node metastases are common in papillary carcinoma, 50% at presentation, and less common in follicular carcinomas. The metastatic nodes in papillary carcinoma may enhance markedly (hypervascular); show increased signal intensity on T1-weighted images (increased thyroglobulin content or hemorrhage); and reveal punctate calcifications. Localized invasion of the larynx, trachea, and esophagus occurs predominantly in papillary and follicular carcinomas; the incidence is less than 5%. Ectopic thyroid tissue may be encountered in the tongue (foramen cecum); along the midline between posterior tongue and isthmus of thyroid gland; lateral neck; mediastinum; and oral cavity. Goiter and malignant tumors, notably papillary carcinoma, may develop in ectopic thyroid tissue. Carcinomas may also arise in thyroglossal duct cysts, which develop from duct remnants between the foramen cecum and thyroid isthmus. Infectious disease of the thyroid gland is not common and the CT and MR imaging findings are similar as described under neck infection. Other types of inflammatory disorders including Hashimoto's thyroiditis, granulomatous thyroiditis, and Riedel's struma display no specific imaging features. Imaging studies may, however, be indicated to confirm a suspected clinical diagnosis and assess compromise of the airway (Riedel's struma). HPT is a clinical diagnosis in which hypercalcemia is the most important finding. Parathyroid hyperplasia, adenoma, and carcinoma represent underlying lesions. To relieve the patient's symptoms surgical extirpation is indicated. The surgical success rate without imaging is 95%. The indications for imaging studies vary but it is generally agreed that reoperation after a previous failed surgical attempt and suspicion of an ectopic parathyroid adenoma should be investigated by imaging. These consist of US, nuclear medicine studies, CT and MR imaging. US and technetium sestamibi scanning have the highest accuracy rate for localizing an adenomatous gland at and near the thyroid gland. Ectopic adenomas, particularly if they are located in the mediastinum, are preferrably investigated with CT and MR imaging with gadolinium and fat suppression. Carcinomas and parathyroid cysts are optimally evaluated by CT and MR imaging. On MR imaging adenomas are low in signal intensity on T1-weighted images, high in signal intensity on T2-weighted images, and enhance post introduction of gadolinium.

Artifactual thickening of the sinus walls on computed tomography: a phantom model and clinical study.

Measuring sinus wall thickness on computed tomography may be important for distinguishing between acute and chronic inflammation of the paranasal sinuses or in cases of a suspected neoplasm. The objective of this study was to investigate the effects of opacified and aerated sinuses on the appearance of sinus wall thickness. A phantom model consisting of a skull half-immersed in water was scanned, and various slice thicknesses and different windows were used. The sinus walls of the water-immersed side appeared to be thicker than those of the aerated side. Bone windows did not completely eliminate this partial volume effect. It was concluded that comparison between a fluid- or tissue-filled sinus and an air-filled counterpart is not accurate enough for evaluating sinus wall thickness. Bone windows do not completely eliminate the artifactual thickening of the bony wall of a filled sinus.

Hajdu-Cheney syndrome with growth hormone deficiency and neuropathy.

A Hajdu-Cheney syndrome is a very rare congenital dysplastic bone disease including acro-osteolysis, short stature, characteristic facies, osteopenia, abnormalities of spine, skull and long bones. A 9 year-old boy presented at our clinic with a chief complaint of short stature and frequent lower respiratory tract infections. He had typical physical and radiographic features of Hajdu-Cheney syndrome associated with growth hormone (GH) deficiency and peripheral motor neuropathy. To our knowledge, this is the first report describing GH deficiency and neuropathy in Hajdu-Cheney syndrome.

Association of intracerebral venous angioma and true arteriovenous malformation: a rare, distinct entity.

We report a mixed cerebrovascular malformation in which a true arteriovenous malformation drained into associated venous angiomas. We describe the MRI and angiographic appearances and review the literature on mixed vascular malformations.

Treatment of hypertension with perindopril reduces plasma atrial natriuretic peptide levels, left ventricular mass, and improves echocardiographic parameters of diastolic function.

BACKGROUND: Hypertension is a major independent risk factor for cardiac deaths, and diastolic dysfunction is a usual finding during the course of this disease. HYPOTHESIS: This study was designed to investigate the effects of chronic therapy with perindopril on left ventricular (LV) mass, left atrial size, diastolic function, and plasma level of atrial natriuretic peptide (ANP) in patients with hypertension. METHODS: Twenty four patients who had not been previously taking any antihypertensive medication and without prior history of angina pectoris, myocardial infarction, congestive heart failure, dysrhythmias, valvular heart disease, or systemic illnesses received 4-8 mg/day of perindopril orally. Echocardiographic studies were acquired at baseline and 6 months after the initiation of therapy. RESULTS: Systolic and diastolic blood pressure decreased from 174 +/- 19.7 and 107.5 +/- 7.8 mmHg to 134 +/- 10.6 and 82 +/- 6.7 mmHg, respectively (p < 0.001). Left ventricular mass decreased from 252.4 +/- 8.3 to 205.7 +/- 7.08 g and left atrial volume from 20.4 +/- 5.1 to 17.6 +/- 5.2 ml, respectively (p < 0.001). Transmitral Doppler early and atrial filling velocity ratio (E/A) increased from 0.69 +/- 0.06 to 0.92 +/- 0.05 m/s and plasma ANP level decreased from 71.9 +/- 11.7 to 35.3 +/- 7.8 pg/ml (p < 0.001). Reduction of LV mass correlated positively with a reduction in ANP levels (r = 0.66, p < 0.0005). CONCLUSIONS: Perindopril caused a significant reduction of LV mass, left atrial volume, and plasma ANP levels, as well as improvement in Doppler parameters of LV filling in this group of patients with hypertension.

Symptomatic cervical synovial cyst associated with an os odontoideum diagnosed by magnetic resonance imaging: case report and review of the literature.

STUDY DESIGN: The first case of a synovial cyst of the upper cervical spine associated with os odontoideum diagnosed by magnetic resonance imaging is presented. OBJECTIVES: To evaluate distinct magnetic resonance imaging findings of a cervical synovial cyst located anterior to the cord and discuss its association with os odontoideum. These findings may guide further investigations. BACKGROUND: Synovial cysts of the spine are uncommon findings. They occur mostly dorsolaterally and with greatest frequency in the lumbar spine and are rarely symptomatic. No association with os odontoideum has been reported before. METHODS: A single subject with symptoms of deterioration in his hand functions was examined by a 2. 0-T magnetic resonance imager. RESULTS: Magnetic resonance imaging of the cervical spine showed an os odontoideum connected to the body of C2 by a synovial joint that had a cystic extension posteriorly compressing the cord. CONCLUSION: Synovial cysts should be considered in the differential diagnosis of an extradural mass of the upper cervical spine. Magnetic resonance imaging should be the choice in the investigation of such cases.

Dynamic contrast-enhanced brain perfusion imaging: technique and clinical applications.

Magnetic resonance (MR) and computed tomographic (CT) perfusion imaging are evolving noninvasive imaging techniques that, unlike conventional MR and CT angiographic methods, can be used to evaluate capillary level tissue perfusion. These techniques can provide early, highly accurate delineation of ischemic tissue, allowing the underlying hemodynamic disturbances of disorders such as stroke and vasospasm to be further analyzed, as well as defining abnormal regions of blood pool in brain tumors. Because MR perfusion (MRP) and CT perfusion (CTP) imaging can assess physiologic parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT), they offer additional data that can be useful in the detection and characterization of entities such as tumor, infection, inflammation, and infarction, which all can have similar appearances on both contrast and noncontrast enhanced conventional CT and MR images. They can also facilitate the further evaluation of processes such as early dementia, psychiatric illnesses, and migraine headaches, which may appear normal on routine CT and MR imaging. MRP and CTP might also be of value in distinguishing residual or recurrent tumor from treatment effects such as radiation-induced necrosis. This article reviews the background principles, scanning techniques, and clinical applications of noninvasive cerebral perfusion imaging.

CT and MR imaging of contact lenses and intraocular lens implants.

To study the image of contact lenses and intraocular lens implants in vitro and in vivo by CT and MRI prospectively. Soft and rigid contact lenses can be seen in vitro in both methods but in vivo imaging was insensitive. Intraocular lens implants were detected in CT and MRI in vitro. In vivo, intra ocular lens implants were detected in all CT, but were harder to detect by the MRI.

Choroid plexus papilloma of foramen of Luschka with multiple recurrences and cystic features.

We present a rare cerebellopontine angle choroid plexus papilloma arising at the foramen of Luschka, without an associated intraventricular component. Distinct features of the tumour on MRI, of multiple recurrences with cystic features, are described, with a review of the literature.