PubMed Health⌕ Search

Biomedical subjects

J D Piekarski

Publications and source records attributed to J D Piekarski.

At least 19 recordsLinked to original sources
PubMed2006

[Vascular tumours and malformation of the orbit].

Vascular diseases are an important part of orbital pathology. We describe vascular tumours of the orbit and vascular diseases with repercussion on the orbit, from intra or extra orbital origin. The classification of these abnormalities is difficult and several terms are used to describe the same histological entity. The objective of this work is, using the current classification, to illustrate the different imaging aspects of the most frequent vascular diseases of the orbit.

Aneurysm↗
PubMed2005

[Imaging of postoperative failures and complications in stapes surgery for otosclerosis].

Otosclerosis (OS) is a dysplasia of the otic capsule located in most cases on the anterior margin of the oval window or fissula ante fenestrum. Progressive conductive hearing loss is the major clinical symptom, due to stapedovestibular ankylosis. Stapes surgery is the only effective treatment of OS, with excellent functional results in more than 90% of cases. However, failures and complications of the surgery may be observed. In theses cases, the etiologic work-up includes imaging evaluation (CT and MRI). Imaging findings are extremely useful in the therapeutic decision. Surgical failure represents 80% of the causes for surgical revision. The main causes of failure are: displacement of the prosthesis, fibrosis of the oval window, erosion of the long process of the incus, incudo-mallear dislocation, obliterative otosclerosis. CT is essential for diagnosis. MR imaging is rarely indicated in the work-up of surgical failures. Labyrinthine complications account for less than 20% of surgical revisions. Etiologies of labyrinthine complications are: intravestibular penetration of the prosthesis, perilymphatic fistula, intra-vestibular granuloma, labyrinthitis and intravestibular bleeding. CT and MRI are complementary for the work up of these complications.

Adult↗
PubMed2004

[Imaging of neuro-ophthalmological emergencies].

MRI often is mandatory in the diagnostic work-up of visual loss, visual field alterations and oculomotor problems. It is performed emergently in patients with painful diplopia associated to mydriasis, to exclude aneurysm, or in patients with painful Horner syndrome to exclude dissection of the internal carotid artery. CT scan in emergency remains useful in case of acute lateral hemianopsia or acute post traumatic visual loss. Progressive neuro-ophthalmological symptoms may require imaging examination in a short delay to define the therapeutic strategy: monocular transient blindness (dissection or carotid stenosis), progressive visual loss (optic nerve compression), bitemporal hemianopsia (optic chiasm lesion), painful visual loss (optic neuritis). A very precise clinical indication is helpful for the choice of imaging protocol and to improve its diagnosis value.

Acute Disease↗
PubMed2002

[How to investigate a patient with exophthalmos?].

Exophthalmos is the main symptom revealing orbital masses. This sign needs to be imaged mainly by MRI and/or CT. As Graves disease is the main etiology of exophthalmos, CT scan should be performed as the initial imaging modality. Indications for US and Doppler are mostly limited to the study of ocular masses, and eventually may help the characterization of extra-ocular lesions. In all cases, imaging is useful to characterize: the precise location of the lesion which can be the intra-conal space (including muscles), the extra-conal space (associated or not to an extra-orbital lesion), or the eyeball; the features of the lesion (density, signal, enhancement.). These findings are used to generate a differential diagnosis. Imaging is also useful to precise the extension of the mass, and in some cases to select the appropriate surgical approach, and for follow-up.

Diagnosis, Differential↗
PubMed2001

[Transcranial Doppler imaging: state of the art].

Initially introduced in the early 1980's, transcranial Doppler followed by transcranial Doppler sonography were used in neurosurgical units for management and follow-up of intracranial vasospasm in patients with subarachnoid hemorrhage. This imaging technique, more sensitive and less invasive than catheter angiography, also proved to be of value for diagnosis of intracranial atherosclerosis, management of patients with head trauma, and evaluation of collateral flow through the circle of Willis. Doppler US would also allow prediction of the risk of symptomatic embolic events through monitoring of HITS. Evaluation of the middle cerebral arteries during carotid occlusion testing is useful for evaluating the need for particular revascularization techniques. Finally, Doppler imaging is useful to assess patients with possible brain death. A recent advance in Doppler imaging is the ability to provide a three-dimensional projection (3D Doppler) of the intracranial arteries enabling improved detection and evaluation of stenoses involving the circle of Willis and improved characterization of intracranial aneurysms. These new applications benefit from the use of US contrast agents and harmonic US imaging.

Brain Death↗
PubMed2001

Pilocytic astrocytoma: unusual feature.

Juvenile pilocytic astrocytoma is a well-defined brain tumor. It most often occurs in children and young adults. It is located in the posterior fossa and has typical imaging features, associating cystic and strongly contrast enhancing mural nodule. After complete surgical removal, its prognosis is excellent. Adult cases are seldom observed. They develop almost exclusively within the cerebral hemispheres and share the same imaging and prognostic characteristics as the pediatric forms. We describe the case of a 42-years-old man presenting with a huge heterogenous posterior fossa lesion. Histopathological analysis of the lesion after surgical resection diagnosed a juvenile pilocytic astrocytoma. These peculiar location and imaging features in an adult patient may be misdiagnosed for infectious lesions and must be recognized.

Adult↗
PubMed2000

Hemodynamic effect of iodinated high-viscosity contrast medium in the rat kidney: a diffusion-weighted MRI feasibility study.

RATIONALE AND OBJECTIVES: To assess the abilities of dynamic diffusion-weighted MRI to demonstrate the effects in vivo of a high-viscosity iodinated contrast agent on medullary and cortical blood flow in the rat kidney. METHODS: Dynamic diffusion-weighted, echoplanar MR images obtained from five b-value single-shot acquisitions and their isotropic apparent diffusion coefficient maps were obtained from nine rats anesthetized by pentobarbital sedation, before and after intravenous injection of a high-viscosity, dimeric iso-osmolar iodinated contrast medium (iodixanol), and compared with those obtained from four control rats that received saline. RESULTS: The mean baseline apparent diffusion coefficient values were 1.64 +/- 0.05 x 10(-3) mm2/s for the cortex and 1.75 +/- 0.06 x 10(-3) mm2/s for the medulla. In the iodixanol group, a significant decrease in renal diffusion was observed at 12 minutes and lasted at least until 24 minutes. The decrease in diffusion occurred earlier for the cortex and lasted less than for the medulla. There was no significant modification in diffusion over time in the control group. CONCLUSIONS: This preliminary experience in rats shows that dynamic diffusion-weighted MRI can be used to study noninvasively the in vivo renal hemodynamic response after injection of iodinated contrast.

Animals↗
PubMed1999

[Value of MRI and computerized tomography scanner in oro-buccopharyngeal cancers with bone invasion].

The purpose of this prospective study was to assess the impact of Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) in the surgical management of carcinomas with mandibular bone invasion. Thirty-five patients with squamous cell carcinoma of oral cavity or oropharynx, with mandibular spread, were studied with both imaging methods before surgical treatment. We compared the radiographic findings with histologic examination. Sensitivity of CTScan and MRI was respectively 25% and 80% to identify bone invasion. CTScan was found less effective in the assessment of bone invasion before mandibular resection and was considered more radiologist dependent. MRI is becoming the imaging method of choice for these cancers, despite inherent disadvantages including limited availability and increased cost over CTScan. MRI is accurate in large oropharyngeal tumors with extension of base of tongue and pterygoid muscle, and to study bone invasion before surgery in oral cavity tumors.

Adult↗
PubMed1998

[3-dimensional computed tomography with model preparation before mandibular reconstruction].

Extended mandibular defects resulting from cancer resection are amenable to reconstruction with a free vascularized bone graft transplantation. Between 1992 and 1995, 12 patients were enrolled in a protocol including a preoperative 3D-CT used to develop a custom-made acrylic model of the mandible. Besides contributing to the assessment of tumor extension, 3D-CT helps determine the adequate limits of mandibular resection. 3D-CT has the advantage of providing the surgeon with a more familiar image of the mandible and the mandibular model, allowing better and quicker conformation of the bone flap. The graft can be shaped at the donor site before cutting its vascular pedicle, resulting in a shorter period of ischemia. This series demonstrated that preoperative mandibular modeling with 3D-CT helps improve functional and cosmetic results in mandibular reconstruction.

Acrylic Resins↗
PubMed1997

[The nasopharynx and deep spaces of the face: anatomy and applications to pathology].

Deep facial spaces are anatomically delineated by the layers of deep cervical fascia. They are located between the skull base and the hyoid bone. Each space contains specific anatomic structures, which can be responsible for specific pathologic processes. Deep facial spaces can be divided in two medial odd spaces (pharyngeal mucosal and retropharyngeal spaces), and in three lateral even spaces (retrostylian, prestylian, and masticator spaces). The dividing of these core tissues are useful for the analysis of the lesions found in this area. CT scan and MRI (with axial and coronal views) provide precise analysis. The main lesions are: -medially, adenoidal hyperplasias and squamous cell carcinomas (pharyngeal mucosal space), adenopathies and abscess (retropharyngeal space). -laterally, salivary tumors (prestylian space), adenopathies, schwannomas and paragangliomas (retrostylian space). Masticator space (and especially pterygopalatine fossa) is an important way of communication and is often involved by the extension of locoregional pathologic processes.

Adenoids↗
PubMed1994

[Collar-button choroidal melanoma. Anatomo-radiologic correlations].

Malignant melanomas of the choroid are the most frequent symptomatic eye tumours in adults. They often have a pathognomonic appearance, being collar-button or mushroom shaped due to rupture of Bruch's membrane by the tumoral mass. The ultrasonographic image of collar-button melanoma is well known: the head of the tumour is hyperechogenic and its base hypoechogenic. According to some authors, this is caused by difference in blood supply between the two parts. At MRI strongly pigmented melanomas emit a high-intensity signal on T1-weighted sequences and a low-intensity signal on T2-weighted sequences, but these characteristic features are inconstant. We present a case of collar-button melanoma explored by ultrasonography, colour Doppler Flow Imaging (CDFI) ultrasound and MRI, then enucleated. Flows and signals were different in front of, or behind the rupture of Bruch's membrane: ultrasounds showed a hyperechogenic image at the head and a hypoechogenic image at the base; on T2-weighted MRI sections intensity was greater in the head than in the base (head: 69 ms, base 180 ms) on CDFI, no flow was detectable in the head and very high flows were seen in the base of the tumour. Comparisons of these images with pathological findings, where there was no difference between head and base in melanin concentration and in cellular type (mixed or mainly epithelioid), led us to believe that the differences observed in images were essentially due to differences in blood supply between the two parts of the tumour constricted by the sides of the ruptured Bruch's membrane.

Bruch Membrane↗
PubMed1992

Adenoid cystic carcinoma of the head and neck: evaluation with MR imaging and clinical-pathologic correlation in 27 patients.

Twenty-seven adenoid cystic carcinomas (ACCs) of the head and neck in 27 patients were evaluated in a retrospective study based on findings at magnetic resonance (MR) imaging and pathologic and clinical examination. Clinical follow-up was obtained over a mean period of 6.3 years (range of follow-up, 3 months to 17 years); all patients underwent one to seven MR examinations. On T2-weighted images, lesions with low signal intensity corresponded to highly cellular tumors (solid subtype) with a poor prognosis; lesions with high signal intensity corresponded to less cellular tumors (cribriform or tubular subtype) with a better prognosis. MR images were not specific in differentiation of ACCs from other types of tumors; this result underscores the need for biopsy to ensure correct diagnosis. Local, intracranial, osseous, and perineural invasion was depicted, but because of its lack of specificity, MR imaging caused overdiagnosis of tumor extension, particularly perineural spread and bone abnormalities.

Adolescent↗