Margaret A. Hall-Craggs

Non-invasive perinatal necropsy by magnetic resonance imaging

BACKGROUND AT present necropsy is done in less than 60% of cases of perinatal death in the UK, despite the value of the procedure to the bereaved parents and their doctors. This low rate reflects the difficulty in discussing the examination during the acute distress after the death of a baby, and the personal and religious objections of many parents to necropsy. We compared post-mortem magnetic resonance imaging (MRI) of the fetus with internal perinatal necropsy to assess whether MRI examination is a feasible option for the 40% of cases where consent for necropsy is not given or requested. METHODS We examined 20 stillborn, miscarried, or aborted fetuses by MRI and necropsy. Scanning was done in a 1.5 T system, in accordance with our protocol, immediately before necropsy. The MRI and necropsy findings were compared to assess how much diagnostic information was obtained by each technique. FINDINGS In eight of the 20 cases the two examinations were in total agreement about the abnormalities present. In eight cases the necropsy provided more detailed information than MRI examination, but in four cases the MRI information was more extensive than that obtained at necropsy. In two of the latter cases, abnormalities of the central nervous system were seen only on MRI. Thus, in 12 (60%) of the 20 cases studied, MRI had equivalent or better diagnostic sensitivity than internal necropsy examination; in 18 (90%) of the 20 cases the two examinations were of similar clinical significance. INTERPRETATION MRI of the stillborn or aborted fetus provides non-invasive access to information previously available only from necropsy.

Cerebral CD8+ lymphocytosis in HIV-1 infected patients with immune restoration induced by HAART

In HIV infected persons, highly active antiretroviral therapy (HAART) has reduced both the morbidity and incidence of several disorders. Its effects on direct HIV-induced damage to the CNS remain controversial. In addition, HAART may provoke an “immune reconstitution inflammatory syndrome” (IRIS). Herein we report two patients who, despite HAART, developed a diffuse encephalopathy. Their clinical, radiological and neuropathological features are described. Immunohistochemical and PCR analyses were used to detect HIV and to exclude other viruses in brain tissue. The unusual inflammatory reaction in the brain tissue was defined by immunohistochemistry. Both patients had advanced HIV disease with low CD4 counts and high HIV “viral loads” before starting HAART. In both, HAART induced an increase in CD4 count and a marked reduction in HIV viral load, which was accompanied, in patient one, by worsening of pre-existing, and, in patient two, by development of, acute encephalopathy. At post-mortem examination, the brain of patient one showed HIV encephalitis. In addition, the brains of both patients revealed HIV–DNA by PCR, diffuse microglial hyperplasia and massive and diffuse perivascular and intraparenchymal infiltration by CD8+/CD4− lymphocytes. We suggest that the rapid immune reconstitution induced by HAART in these two patients led to a redistribution of lymphocytes into peripheral blood. This was followed by recruitment of CD8+ lymphocytes into the brain, which resulted in the diffuse infiltration described. The appearances in patient two further suggest that HIV brain infection, even without encephalitis, is sufficient to trigger this response.

Guidelines for the use of imaging in the management of myeloma

In 2001, reference to the use of imaging in the British Committee for Standards in Haematology guidelines for the diagnosis and management of myeloma was confined to the standard use of plain X‐rays in the diagnostic skeletal survey and emergency use of computed tomography (CT) and magnetic resonance (MR) imaging in the setting of cord compression. Since then, there has been a steady rise in interest in the use of various imaging techniques in the management of myeloma. The purpose of imaging in the management of myeloma includes the assessment of the extent and severity of the disease at presentation, the identification and characterisation of complications, and the assessment of response to therapy. Plain radiography, CT, and MR imaging are generally established examination techniques in myeloma whilst positron emission tomography (PET) and 99Technetium sestamibi (MIBI) imaging are promising newer scanning techniques under current evaluation. These stand‐alone imaging guidelines discuss recommendations for the use of each modality of imaging at diagnosis and in the follow up of patients with myeloma.

Three-dimensional CT analysis to determine acetabular retroversion and the implications for the management of femoro-acetabular impingement

This study examined the relationship between the cross-over sign and the true three-dimensional anatomical version of the acetabulum. We also investigated whether in true retroversion there is excessive femoral head cover anteriorly. Radiographs of 64 hips in patients being investigated for symptoms of femoro-acetabular impingement were analysed and the presence of a cross-over sign was documented. CT scans of the same hips were analysed to determine anatomical version and femoral head cover in relation to the anterior pelvic plane after correcting for pelvic tilt. The sensitivity and specificity of the cross-over sign were 92% and 55%, respectively for identifying true acetabular retroversion. There was no significant difference in total cover between normal and retroverted cases. Anterior and posterior cover were, however, significantly different (p < 0.001 and 0.002). The cross-over sign was found to be sensitive but not specific. The results for femoral head cover suggest that retroversion is characterised by posterior deficiency but increased cover anteriorly.

Reduced movement of median nerve in carpal tunnel during wrist flexion in patients with non-specific arm pain

Magnetic resonance scans on patients with non-specific arm pain (repetitive strain injury) show reduced median-nerve movement in the carpal tunnel, suggesting that this common condition may involve nerve entrapment.

Analysis of cover of the femoral head in normal and dysplastic hips: NEW CT-BASED TECHNIQUE

We present a new CT-based method which measures cover of the femoral head in both normal and dysplastic hips and allows assessment of acetabular inclination and anteversion. A clear topographical image of the head with its covered area is generated. We studied 36 normal and 39 dysplastic hips. In the normal hips the mean cover was 73% (66% to 81%), whereas in the dysplastic group it was 51% (38% to 64%). The significant advantage of this technique is that it allows the measurements to be standardised with reference to a specific anatomical plane. When this is applied to assessing cover in surgery for dysplasia of the hip it gives a clearer understanding of where the corrected hip stands in relation to normal and allows accurate assessment of inclination and anteversion.

The Use of Ultrasound Imaging to Demonstrate Reduced Movement of the Median Nerve during Wrist Flexion in Patients with Non-Specific Arm Pain

Following clinical screening, we examined movement of the median nerve at the wrist using high-resolution (10–22 MHz) ultrasound in 16 controls and 12 patients with non-specific arm pain (also referred to as repetitive strain injury). Imaging was performed just proximal to the carpal tunnel with the wrist in neutral, 30 degrees of extension and 30 degrees of flexion. In control subjects the position of the median nerve was 4.8 (SE=0.4) mm more radial with the wrist flexed than with the wrist extended. In the twelve arm pain patients the average change was only 1.2 (SE=0.5) mm. It appears that ultrasound imaging may be helpful in diagnosing non-specific arm pain, a condition for which there are no well-defined diagnostic tests at present. The reduced nerve movement seen with ultrasound imaging confirms previous work with magnetic resonance imaging.

Proton MRS and quantitative MRI assessment of the short term neurological response to antiretroviral therapy in AIDS

OBJECTIVE To investigate MRI and proton spectroscopy changes in five patients with HIV associated dementia complex (HADC) treated with antiretroviral therapy. METHODS Three markers were evaluated: (1) CSF/intracranial volume ratio; (2) T2 weighted signal ratio between parieto-occipital white and subcortical grey matter; and (3) metabolite ratios from long echo time (TE=135 ms) single voxel proton spectra of parieto-occipital white matter. RESULTS Spectroscopic changes indicated initial increases in N-acetyl/(N-acetyl + choline + creatine) ratio (NA/(NA+ Cho+Cr)) and progression of atrophy after initiation of antiretroviral therapy in four of five patients. When the neurological status of the patients subsequently deteriorated (two of five patients), the NA/(NA+Cho+Cr) ratio also declined. CONCLUSIONS spectroscopic changes mirror reversible neuronal dysfunction. These objective, non-invasive techniques may be used for monitoring the neurological effects of antiretroviral drug therapy in patients with HADC.

Interstitial laser photocoagulation for the treatment of osteoid osteoma: RESULTS OF A PROSPECTIVE STUDY

We report the results of a prospective study of 23 patients in which interstitial laser photocoagulation (ILP) was used to treat an osteoid osteoma. ILP is a technique in which tumour tissue is destroyed by direct heating using low-power laser light energy delivered by thin (400 microm) optical fibres which are introduced percutaneously into the tumour under image guidance. Pain was evaluated before operation and at the latest follow-up using a visual analogue scale with 0 denoting no pain and 10 the worst pain imaginable. The mean follow-up was for 15 months. The results showed that the mean pain score decreased from 7.5 before operation to 0.95 at the latest follow-up. Fourteen patients had no pain and eight had minor discomfort, not requiring analgesia. One patient required a second procedure because placement of the fibre had not been accurate enough and one developed recurrent symptoms eight months after treatment. All patients were satisfied with the operation because of the rapid resolution of pain, the minimally invasive nature of the procedure, and the fact that there was no postoperative restriction of activity.

Analysis of acetabular version in the native hip: comparison between 2D axial CT and 3D CT measurements

ObjectiveTo compare two-dimensional (2D) axial with three-dimensional (3D) computerized tomography (CT) measurements of acetabular version in native hips.Materials and methodsCT scans of 34 hips in 17 consecutive patients being investigated for femoroacetabular impingement were analyzed. Acetabular version was measured using 2D CT at two different axial levels, one cranial (slice 2) and the other at the equator (slice 3). The measurements were repeated after correction for pelvic tilt. The results were compared to the measurements of anatomical version obtained using a 3D CT method that automatically corrects for pelvic tilt.ResultsThe mean acetabular version using the 3D CT method was 15.7° (SD 6.9°). The mean version using slice 2 was 9.3° (SD 6.5°) before correction for pelvic tilt and 15.7° (SD 8.0°) after the correction. The mean version using slice 3 was 16.4° (SD 4.2°) before tilt correction and 19.0° (SD 5.0°) after the correction. In relation to the 3D method, the intraclass correlation coefficient (ICC) was 0.58 for the uncorrected and 0.93 for the corrected slice 2 method. For the uncorrected and corrected slice 3 methods, the ICC was 0.64 and 0.89, respectively.ConclusionsThe 2D axial methods produced variable results. The results that correlated best with the 3D method were those of the cranial slice (slice 2) after correction for pelvic tilt. Interpretation of 2D axial CT measurements of acetabular version should be done with caution. The level at which the measurement is done and the presence of pelvic tilt appear to be significant factors.