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Biomedical subjects

Donald M Hadley

Publications and source records attributed to Donald M Hadley.

11 recordsLinked to original sources
PubMed2006

Successful antiparkinsonian medication withdrawal in patients with Parkinsonism and normal FP-CIT SPECT.

Between 4% and 14% of patients diagnosed with Parkinson's disease and entering clinical trials have normal presynaptic dopaminergic imaging. The effects of antiparkinsonian therapy have varied in these studies, and the consequences of stopping treatment are not reported. We present 11 patients who initially fulfilled diagnostic criteria and were treated for Parkinson's disease but in whom emerging diagnostic doubts led to antiparkinsonian therapy withdrawal, which was achieved without deterioration. Such cases represent a nondegenerative form of Parkinsonism, which does not benefit from dopaminergic therapy. Prospective vigilance regarding this category is of importance in clinical practice and clinical trials.

Aged↗
PubMed2006

Assessment of 123I-FIAU imaging of herpes simplex viral gene expression in the treatment of glioma.

BACKGROUND: Herpes simplex virus 1716 (HSV1716), a selectively replication competent mutant of HSV1, is under investigation as an oncolytic viral therapy in human malignant glioma. As with similar therapies, a technique for measurement of viral replication and distribution over time following virus administration is required. Imaging expression of the HSV-thymidine kinase (HSV-tk) gene offers an opportunity for non-invasive assessment of viral distribution in living subjects. This is the first study to explore the use of HSV-tk as a reporter gene and radiolabelled thymidine analogue 5-[(123)I]iodo-1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl) uracil ((123)I-FIAU) as a marker substrate to non-invasively monitor HSV1716 replication in humans during treatment of high-grade glioma. METHODS: I-FIAU brain SPECT imaging was undertaken in eight patients receiving intra-tumoural injection of HSV1716, before and after administration of the virus. Baseline images were acquired 3 days prior to virus administration and between 1 and 5 days following virus administration. Region of interest analysis was used to investigate whether there was an increase in (123)I-FIAU concentration following virus administration due to HSV-tk expression. RESULT: Increased (123)I-FIAU accumulation due to HSV-tk expression was not detected in this study. The possible explanations for this finding are explored and design options for future studies are discussed.

Arabinofuranosyluracil↗
PubMed2006

Two-year follow-up in 150 consecutive cases with normal dopamine transporter imaging.

BACKGROUND AND AIMS: Functional pre-synaptic dopamine brain imaging is generally abnormal when parkinsonism is degenerative (such as in idiopathic Parkinson's disease) and normal in patients with non-degenerative movement disorder (such as essential tremor). However, some patients diagnosed as early Parkinson's disease have normal presynaptic dopamine imaging. Follow-up of patients with normal imaging should help determine whether such patients truly have degenerative parkinsonism (and therefore represent false negative imaging results), or emerge as cases of non-degenerative parkinsonism (and therefore represent initial clinical over-diagnosis of Parkinson's disease). METHODS AND RESULTS: One hundred and fifty cases with normal I-FP-CIT SPECT undertaken during routine care over a 3-year period were reviewed 2.4 years (interquartile range, 2.2-3.1 years) after SPECT. Diagnosis after follow-up was non-degenerative parkinsonism or tremor in 146 (97%), who did not progress clinically, and degenerative parkinsonism in four (3%), in whom clinical progression was noted. Anti-Parkinson therapy was used in 36, and withdrawn in 27 with no deterioration in 25. Patients strictly fulfilling Brain Bank criteria (part 1) were more likely to undergo a trial of anti-Parkinson therapy (P < 0.05) but were no more likely to maintain or respond to anti-Parkinson therapy than those not fulfilling criteria. CONCLUSION: The clinical profile and therapy response during follow-up of patients with normal presynaptic dopamine imaging supports the diagnosis of a non-degenerative movement disorder in nearly all cases.

Antiparkinson Agents↗
PubMed2005

Measurement of tumor "size" in recurrent malignant glioma: 1D, 2D, or 3D?

BACKGROUND AND PURPOSE: Tumor "size" is used internationally as a surrogate marker for overall survival when following current response assessment protocols (World Health Organization and Response Evaluation Criteria in Solid Tumors). With little evidence of a relationship between tumor "size" and survival in intrinsic brain tumors, this study was undertaken to investigate the predictive value of MR imaging-defined tumor size for survival in patients with recurrent malignant glioma and to compare the different measures of tumor size used in these current response assessment protocols. METHODS: Volumetric, bidimensional, and unidimensional measurements of tumor size were made using baseline contrast-enhanced T1-weighted images of 70 patients with recurrent malignant glioma receiving intravenous chemotherapy. Cox's proportional hazards model was used to investigate the prognostic importance of tumor size using survival as the end point. Further statistical analysis was undertaken to investigate the relationship between the different measurement techniques. RESULTS: Only the volumetric measurement of tumor size was found to be predictive of survival in recurrent malignant glioma on both univariate and multivariate analysis. Furthermore, analysis demonstrated that the unidimensional and bidimensional measures of tumor were not comparable with the more accurate and direct volumetric measurement. CONCLUSION: Indirect unidimensional and bidimensional measurement techniques do not have a significant association with overall survival or adequately assess tumor size in recurrent malignant glioma. These findings have serious implications about the validity of using current response assessment protocols in therapy trials for recurrent malignant glioma.

Adult↗
PubMed2004

Perfusion SPECT in cochlear implantation and promontory stimulation.

BACKGROUND: Recent studies of profoundly deaf patients with cochlear implants have demonstrated that these patients are able to process sound in the auditory cortex in a similar way to normal subjects. However, there are large variations in outcome. Various clinical criteria are used for subject selection and the decision as to which ear is to be implanted involves electrical stimulation of the promontory which is used to confirm the persistence of auditory neurones and fibres that can be utilized by the cochlear implant. In this study we have used SPECT with Tc-HMPAO to investigate activation of the auditory cortex in cochlear implantees post-surgery. In addition we also investigated whether electrical stimulation of the promontory does produce change in blood flow in the auditory cortex in pre-surgery candidates, which would indicate viable auditory networks that can be utilized by a cochlear implant device. METHODS AND RESULTS: Image analysis was performed with SPM99. Results of a simple subtraction paradigm indicated bilateral activation of auditory cortex and Wernicke's area in the post-implant group during auditory stimulus (speech) and bilateral activation of the ventral lateral posterior thalamus and bilateral auditory association cortex BA21/22/42, in the pre-implant group during electrical stimulus but no activation of the primary auditory cortex. A conjunction analysis used to investigate the common areas of activation across both groups during the stimulus condition showed that there was a common bilateral activation of the primary auditory cortex in both groups (BA22/41/42). In addition, analysis of a subset of the seven post-implant subjects who did not comprehend the speech in our study showed an activation (Pu<0.05, where Pu is the peak voxel threshold, uncorrected for multiple comparisons) in the left auditory cortex that extended into area BA22 synonymous with Wernicke's area. This supports the theory that this region has a sensory role.

Adult↗
PubMed2003

Prospective study of presynaptic dopaminergic imaging in patients with mild parkinsonism and tremor disorders: part 1. Baseline and 3-month observations.

To record prospectively, from early presentation, the clinical features of parkinsonism and tremor disorders, in relation to evidence of dopaminergic deficit shown with [(123)I]-FP-CIT (DaTSCAN, Amersham Health) single photon emission computerised tomography (SPECT). Clinical signs were recorded in 62 patients, of whom 24 failed standard Parkinson's disease (PD) and essential tremor criteria, and 38 fulfilled UK Brain Bank step 1 PD criteria. Striatal radioligand uptake was graded visually as normal or abnormal, and specific:nonspecific ratios were calculated. Bradykinesia and rigidity showed significant overall association with abnormal scans (P < or = 0.003), but rest tremor did not (P = NS). In the 24 patients not fulfilling specific criteria (mean age 63 [SD 9] years, disease duration 3 [SD 4] years), 10 (42%) had abnormal visual SPECT assessment and 14 (58%) had normal scans. Of 38 patients with early PD by clinical criteria (mean age 60 [SD 9] years, disease duration 3 [SD 1.7] years), 33 (87%) were visually abnormal. Baseline clinical diagnosis corresponded with SPECT imaging results in 51 of 62 cases (82%), which increased to 56 of 62 cases (90%) with amendment of seven clinical diagnoses at 3 months (blind to SPECT results). Akinetic-rigid cardinal diagnostic features of parkinsonism associate well with dopaminergic deficit in patients with early and mild clinical features. When these clinical features are uncertain, or the patient fails clinical diagnostic criteria, testing for dopaminergic deficit with [(123)I]-FP-CIT SPECT may assist the diagnostic process.

Adult↗
PubMed2002

MRI safety review.

Magnetic resonance is an extremely powerful imaging tool which does not expose patients to ionizing radiation. However, there are risks associated with the MR environment which all staff must be aware of and eliminate. The aim of this article is to highlight the well known and not so well known potentially adverse interactions. Although many safety investigations have been carried out at up to 1.5T, the reader will be reminded that as many centres install magnets of 2.0T and above, much of the current safety literature cannot be simply extrapolated to these higher field strengths and further investigations will be required to reassure staff and patients of the limits of their safe use.

Foreign Bodies↗
PubMed2002

MR findings in intralabyrinthine schwannomas.

AIM: Intralabyrinthine schwannomas (ILS) are rare benign tumours. They are not always recognized on routine magnetic resonance imaging (MRI). We aimed to study the clinical presentation and MRI findings in our patients with ILS. MATERIALS AND METHODS: Retrospective analysis of patients with vestibular schwannomas treated at this center. RESULTS: Of 144 vestibular schwannomas studied at this centre, three patients had an ILS. The most common presenting symptoms were unilateral hearing loss, tinnitus and vertigo. Two patients demonstrated a progressive sensorineural hearing loss (SNHL). The third patient had a severe SNHL at presentation. MRI enhanced with contrast medium was positive in the two patients with progressive SNHL and negative in the patient with the severe SNHL. CONCLUSION: This series demonstrates the ability of MRI to identify schwannomas filling the labyrinth, and also its inability to identify extremely small ILS. It underlines the importance of sending the cristae of patients undergoing labyrinthectomy for presumed Ménière's disease for histological examination.

Adult↗
PubMed2002

SPECT imaging in head injury interpreted with statistical parametric mapping.

UNLABELLED: This study investigated regional cerebral blood flow in head-injured patients using statistical parametric mapping (SPM) to detect hypoperfusion on (99m)Tc-hexamethylpropyleneamine oxime (HMPAO) SPECT scans. METHODS: Acute and follow-up SPECT and MRI scans from 61 patients who were admitted to a regional neurosurgical unit were examined. Patients had acute MRI and SPECT at 2-18 d after injury and on follow-up between 130 and 366 d after injury. Thirty-two scans from non-head-injured patients were used as a SPECT control group. The SPECT images were first aligned to the Talairach-Tournoux atlas and then analyzed statistically with SPM. RESULTS: SPECT detected more extensive abnormality than MRI in acute and follow-up stages. This effect was more pronounced on follow-up of patients with diffuse injury. Examination of a focal injury group indicated the involvement of frontal and temporal lobes and the anterior cingulate. Blood flow abnormalities persist, to a lesser extent, on follow-up scans. The diffuse group displayed low blood flow in the frontal and temporal lobes, including cingulate involvement, which persists at follow-up with additional involvement of the thalamus. CONCLUSION: SPM has a role in SPECT image interpretation because it allows better visualization than other methods of quantitative analysis of the spatial distribution of abnormalities in focal and diffuse head injury. Frontal lobe blood flow abnormality (particularly anterofrontal regions and mesiofrontal areas) is common after head injury.

Adolescent↗
PubMed2002

3D stereophotogrammetric image superimposition onto 3D CT scan images: the future of orthognathic surgery. A pilot study.

The aim of this study was to register and assess the accuracy of the superimposition method of a 3-dimensional (3D) soft tissue stereophotogrammetric image (C3D image) and a 3D image of the underlying skeletal tissue acquired by 3D spiral computerized tomography (CT). The study was conducted on a model head, in which an intact human skull was embedded with an overlying latex mask that reproduced anatomic features of a human face. Ten artificial radiopaque landmarks were secured to the surface of the latex mask. A stereophotogrammetric image of the mask and a 3D spiral CT image of the model head were captured. The C3D image and the CT images were registered for superimposition by 3 different methods: Procrustes superimposition using artificial landmarks, Procrustes analysis using anatomic landmarks, and partial Procrustes analysis using anatomic landmarks and then registration completion by HICP (a modified Iterative Closest Point algorithm) using a specified region of both images. The results showed that Procrustes superimposition using the artificial landmarks produced an error of superimposition on the order of 10 mm. Procrustes analysis using anatomic landmarks produced an error in the order of 2 mm. Partial Procrustes analysis using anatomic landmarks followed by HICP produced a superimposition accuracy of between 1.25 and 1.5 mm. It was concluded that a stereophotogrammetric and a 3D spiral CT scan image can be superimposed with an accuracy of between 1.25 and 1.5 mm using partial Procrustes analysis based on anatomic landmarks and then registration completion by HICP.

Algorithms↗