John P. Stack

The Role of Discography in Lumbar Disc Disease: A Comparative Study of Magnetic Resonance Imaging and Discography

This study reviews prospectively a series of 29 patients who were examined by magnetic resonance imaging (MRI) and discography for degenerative disc disease. All had persistent low-back pain and non-diagnostic initial investigations, including plain films, myelography and/or computed tomography (CT). The imaging characteristics for degenerative disc disease correlated in 65 out of 73 intervertebral levels. All symptomatic discs were degenerate on both MRI and discography. Features of degenerative disc disease on MRI were assessed retrospectively, with a view to identifying the symptomatic level as defined by discography. MRI could not reliably detect this level, particularly in those with multi-level degenerative disc disease. Positive reproduction of symptoms at discography was the criteria used for surgery. All 12 patients in this group had posterior spinal fusion performed. Nine improved and three were unchanged. Of the ancillary features associated with disc degeneration, only a bulging annulus fibrosis proved to be of any value on MRI. Nonetheless, MRI should be used as the primary investigation in this patient group as it can lead to a marked reduction in the number of disc levels requiring injection.

A comparison of modern imaging modalities in osteonecrosis of the femoral head

Eleven symptomatic and seven asymptomatic patients, considered to be at high risk of osteonecrosis of the hip, were studied using plain radiography, scintigraphy, computed tomography (CT) with multiplanar reconstruction (MPR), and magnetic resonance imaging (MRI), to determine the precise roles of the various imaging modalities in detecting and staging femoral head osteonecrosis, and to evaluate the incidence in an asymptomatic high-risk patient group. Osteonecrosis was best detected by MRI and was particularly useful for the diagnosis of early disease when other imaging modalities were negative. It is recommended that MRI be performed for the detection of early osteonecrosis, while CT/MPR be used for accurate staging and treatment planning in the established disease.

Digital subtraction in Gd-DTPA enhanced imaging of the breast.

PURPOSE This study examines the role of digital subtraction magnetic resonance imaging (MRI) of the breast in the interpretation of the morphology and characteristics of breast disease. METHODS Thirty-one patients with an abnormal mammogram or clinically palpable abnormality underwent MRI of the breast prior to surgical excision of the lesion. FLASH 3-D images of the breast were acquired before and after IV contrast injection of Gd-DTPA. Digital subtraction was performed on selected images. The images were independently assessed by two radiologists experienced in both mammography and MRI. RESULTS Accurate diagnosis was possible in 29 out of 31 patients using the subtraction technique compared to 23 cases using the pre-subtraction images alone. The actual extent of disease and multicentricity were also better appreciated on the subtracted image. Subtraction also provided better identification of tumour recurrence in the post-operative and post-radiotherapy breast. Chest wall and lymph node involvement were more easily appreciated on the subtraction images. CONCLUSION Digital subtraction is a simple, effective and relatively cheap technique which can aid in the interpretation of magnetic resonance imaging of the breast.

One-and-a-half syndrome following intravenous morphine injection in a drug user

A 25-year-old man presented with a history of headache; dizziness and diplopia after intravenous injection of dissolved morphine sulphate tablets. He had no other symptoms of cerebellar or brainstem dysfunction. On examination, a left one-and-a-half syndrome, right paralytic pontine exotropia and left partial lower facial nerve palsy were found. Radiological examination with M.R.I, brain scan showed a pontine infarct at the level of the facial and auditory nerve complex. Gradual recovery after dexamethasone therapy.

Segmentation of the biliary tree in MRCP data

Magnetic Resonance Cholangiopancreatography (MRCP) is a type of MR imaging which utilizes protocols designed to enhance stationary fluids in the imaged volume. In this way it visualizes the pancreatobiliary tract by highlighting the bile and pancreatic juices in the system. Current practice sees this data being assessed directly, with little or no processing being performed prior to review. MRCP data presents three main difficulties when it comes to image processing. The first is the relatively noisy nature of the data. Second is its low spatial resolution, especially in the inter-slice direction. And third, the variability observed between MRCP studies, which makes consistent results difficult to attain. This paper describes the initial phase of research which aims to develop assistive image analysis techniques to aid in the interpretation of MRCP data. The first stage in this process is the robust segmentation of the pancreatobiliary system. To this end a segmentation procedure has been developed using an approach based on the tools and techniques of the mathematical morphology. This paper examines the task at hand and presents initial results, describing and assessing the segmentation approach developed.

Large pontine lesions in demyelinating disease may mimic brainstem gliomas on magnetic resonance imaging

This paper reports two patients who had clinical disorders of eye movements which suggested discrete brainstem lesions. When magnetic resonance imaging (MRI) was performed, areas of demyelination far larger than expected were demonstrated and which had mass effect mimicking brainstem glioma. In both cases, there was clinical improvement with resolution of the MRI lesions without steroids or other treatment. The literature on MRI scanning in demyelinating disease is reviewed. MRI is an invaluable diagnostic tool in eye movement disorders related to demyelination, although the clinician must be aware of its limitations in tissue differentiation. We suspect that many ophthalmologists are unaware that the MRI appearances of demyelination may mimic tumour, particularly if it has mass effect.