Serial Single Photon Emission Computed Tomography Research Articles

A Conjugation Strategy to Modulate Antigen Binding and FcRn Interaction Leads to Improved Tumor Targeting and Radioimmunotherapy Efficacy with an Antibody Targeting Prostate-Specific Antigen.

Simple SummaryThe present study demonstrates that a radiolabeling strategy can positively modify hu5A10′s capacity to bind PSA and complex with the FcRn receptor, which results in a more homogenous activity distribution in tumors and enhanced therapy efficacy. These new innovative radiochemistry ideas could potentially decrease relapse of tumors in patients treated with internalizing antibodies.Background: The humanized monoclonal antibody (mAb) hu5A10 specifically targets and internalizes prostate cancer cells by binding to prostate specific antigen (PSA). Preclinical evaluations have shown that hu5A10 is an excellent vehicle for prostate cancer (PCa) radiotheranostics. We studied the impact of different chelates and conjugation ratios on hu5A10′s target affinity, neonatal fc-receptor interaction on in vivo targeting efficacy, and possible enhanced therapeutic efficacy. Methods: In our experiment, humanized 5A10 (hu5A10) was conjugated with DOTA or DTPA at a molar ratio of 3:1, 6:1, and 12:1. Surface plasmon resonance (SPR) was used to study antigen and FcRn binding to the antibody conjugates. [111In]hu5A10 radio-immunoconjugates were administered intravenously into BALB/c mice carrying subcutaneous LNCaP xenografts. Serial Single-photon emission computed tomography (SPECT) images were obtained during the first week. Tumors were harvested and radionuclide distribution was analyzed by autoradiography along with microanatomy and immunohistochemistry. Results: As seen by SPR, the binding to PSA was clearly affected by the chelate-to-antibody ratio. Similarly, FcRn (neonatal fc-receptor) interacted less with antibodies conjugated at high ratios of chelator, which was more pronounced for DOTA conjugates. The autoradiography data indicated a higher distribution of radioactivity to the rim of the tumor for lower ratios and a more homogenous distribution at higher ratios. Mice injected with ratio 3:1 111In-DOTA-hu5A10 showed no significant difference in tumor volume when compared to mice given vehicle over a time period of 3 weeks. Mice given a similar injection of ratio 6:1 111In-DOTA-hu5A10 or 6:1 111In-DTPA-hu5A10 or 12:1 111In-DTPA-hu5A10 showed significant tumor growth retardation. Conclusions: The present study demonstrated that the radiolabeling strategy could positively modify the hu5A10′s capacity to bind PSA and complex with the FcRn-receptor, which resulted in more homogenous activity distribution in tumors and enhanced therapy efficacy.

Reducing the number of CTs performed to monitor personalized dosimetry during peptide receptor radionuclide therapy (PRRT)

BackgroundPeptide receptor radionuclide therapy (PRRT) with [177Lu]-DOTA-TATE is an effective treatment of neuroendocrine tumors (NETs). After each cycle of treatment, patient dosimetry evaluates the radiation dose to the risk organs, kidneys, and bone marrow, the most radiosensitive tissues. Absorbed doses are calculated from the radioactivity in the blood and from single photon emission computed tomography (SPECT) images corrected by computed tomography (CT) acquired after each course of treatment. The aim of this work is to assess whether the dosimetry along all treatment cycles can be calculated using a single CT. We hypothesize that the absorbed doses to the risk organs calculated with a single CT will be accurate enough to correctly manage the patients, i.e., whether or not to continue PRRT.Twenty-four patients diagnosed with metastatic NETs undergoing PRRT with [177Lu]-DOTA-TATE were retrospectively included in this study. We compared radiation doses to the kidneys and bone marrow using two protocols. In the “classical” one, dosimetry is calculated based on a SPECT and a CT after each treatment cycle. In the new protocol, dosimetry is calculated based on a SPECT study after each cycle but with the first acquired CT for all cycles.ResultsThe decision whether or not to stop PRRT because of unsafe absorbed dose to the risk organs would have been the same had the classical or the new protocol been used. The agreement between the cumulative doses to the kidneys and bone marrow obtained from the two protocols was excellent with Pearson’s correlation coefficients r = 0.95 and r = 0.99 (P < 0.0001) and mean relative differences of 5.30 ± 6.20% and 0.48 ± 4.88%, respectively.ConclusionsDosimetry calculations for a given patient can be done using a single CT registered to serial SPECTs. This new protocol reduces the need for a hybrid camera in the follow-up of patients receiving [177Lu]-DOTA-TATE.

Reduced CBF recovery detected by longitudinal 3D‐SSP SPECT analyses predicts outcome of postoperative patients after subarachnoid haemorrhage

The aim of this study was to evaluate the impact of cerebral blood flow (CBF) recovery obtained from brain single-photon emission computed tomography (SPECT) images on postoperative outcome after aneurysmal subarachnoid haemorrhage (SAH). Twenty-nine patients who had undergone surgical clipping for ruptured anterior communicating artery aneurysms were analyzed prospectively. Routine measurements of CBF were performed using technetium-99m hexamethyl propyleneamine oxine SPECT on days 4 and 14 after SAH. Regional voxel data analyzed by three dimensional stereotactic surface projection (3D-SSP) were compared between patients and age-matched normal database (NDB). In 3D-SSP analysis of all patients, cortical hypoperfusion around the surgical site in bilateral frontal lobes was evident on day 4 (P<.05 vs NDB), which was improved significantly on day 14. However, the recovery was less complete in patients with poor clinical grades (P<.05) and presenting symptoms attributable to delayed cerebral ischaemia (DCI) (P<.05) than those without. Multivariate analysis showed that patients with mild to moderate CBF recovery (relative Z-score differences of <4) (P=.014; odds ratio, 2.5; 95% confidence interval, 1.93-3.31) was independently associated with poor functional outcome at 3months. We conclude that reduced CBF recovery detected by serial 3D-SSP SPECT image analyses can be a potential predictor of poor prognosis in postoperative patients after SAH.

Preserved regional cerebral blood flow in the occipital cortices, brainstem, and cerebellum of patients with V180I-129M genetic Creutzfeldt-Jakob disease in serial SPECT studies

Creutzfeldt-Jakob disease (CJD) with a causative point mutation of valine to isoleucine at codon 180 (V180I) is one of the major types of genetic CJD (gCJD) in Japan. V180I gCJD is rarely accompanied by a family history, and its clinical characteristics include late-onset, long disease duration, and edematous cortical hyperintensity in diffusion, fluid attenuate inversion and T2-weighted MRI. We performed serial imaging with single-photon emission computed tomography (SPECT) and MRI in three V180I gCJD cases over long-term observation. All cases were characterized by progressive dementia, parkinsonism, and the absence of cerebellar signs or cortical visual dysfunction in their clinical courses. Moreover, during the end-stage, SPECT findings showed preserved regional cerebral blood flow (rCBF) in the occipital cortices, brainstem, and cerebellum. Similarly, no apparent atrophy or increased signal intensities were observed in MRI images of the occipital and cerebellar regions. In conclusion, we report a decrease in rCBF predominantly in the frontal and temporal cortices during the early-stage, which became more widespread as the disease progressed. Importantly, rCBF was preserved in the occipital cortices, brainstem, and cerebellar regions until the end-stage, which may be distinct to V180I gCJD cases.

Visualizing dopamine transporter integrity with iodine-123-FP-CIT SPECT in combination with high resolution MRI in the brain of the common marmoset monkey

Considerable progress has been made in small animal single photon emission computed tomography (SPECT) imaging in the field of Parkinson's disease. In preclinical research, there is an increasing demand for in vivo imaging techniques to apply to animal models. Here, we report the first protocol for dopamine transporter (DAT) SPECT in common marmosets using the radioligand 123I-N-ω-fluoropropyl-2β-carbomethoxy-3β-{4-iodophenyl}nortropane (123I-FP-CIT). Serial SPECT images were obtained on an upgraded clinical scanner to determine the distribution kinetics of 123I-FP-CIT in the marmoset brain. After intravenous injection of approximately 60MBq of the radiotracer 123I-FP-CIT, stable and specific striatal uptake was observed for at least 4h. Analysis of plasma samples showed rapid disappearance of the radiotracer from blood plasma within a few minutes after application, with activity declining to 4.1% of the administered activity. Structural magnetic resonance imaging (MRI) at 400μm resolution provided the details of the underlying anatomy. In a marmoset model of Parkinson's disease, which was generated by unilateral injections of 6-hydroxydopamine (6-OHDA) into the nigro-striatal projection pathway, complete loss of striatal DAT binding in combination with behavioral deficits was observed. The presented study demonstrates that 123I-FP-CIT SPECT is a suitable tool to investigate DAT integrity in preclinical studies on common marmosets.

Serial diffusion-weighted MRI and SPECT findings in a Creutzfeldt–Jakob disease patient with V180I mutation

We report serial changes of diffusion-weighted imaging (DWI) and single photon emission computed tomography (SPECT) in a patient with Creutzfeldt–Jakob disease with V180I mutation (CJD180). DWI abnormalities in our patient were more predominantly observed in the left cerebral cortex than left basal ganglia. Hemilateral abnormalities progressed over 5 months to involve the contralateral side with increasing DWI signals. At 6 months, SPECT showed hypoperfusion in the left parietal and frontal lobes and the hypoperfusion region spread to the bilateral basal ganglia, right parietal and frontal lobes. SPECT imaging revealed marked cerebral blood flow reduction, predominantly in the cerebral cortex corresponding to brain areas with high-intensity DWI signals. During the follow-up period of CJD180, DWI was more sensitive than conventional FLAIR and T2-weighted images (T2WI) to detect and monitor the progression of abnormal hyperintense lesions. We suggest that serial DWI and SPECT findings are useful for not only early diagnosis of CJD but also for monitoring disease progression.

Direct Minimally Invasive Intramyocardial Injection of Bone Marrow-Derived AC133+ Stem Cells in Patients with Refractory Ischemia: Preliminary Results

Bone marrow-derived stem cells (BMSC) may represent a viable option for patients with myocardial ischemia refractory to conventional treatments. In 5 patients (4 males and 1 female, mean age 64 +/- 8 years) with untreatable angina pectoris (Canadian Cardiovascular Society Class III/IV), myocardial segments with stress-induced ischemia as assessed by gated single-photon emission computed tomography were injected with 4 to 12 million CD133+ BMSC. Cells were injected into the myocardium (2 anterior, 2 lateral, 1 inferior wall) through minimally invasive approaches (left minithoracotomy [n = 4] and subdiaphragmatic approach [n = 1]). At baseline, at 6 months and at 1 year of follow-up, an exercise test, gated single-photon emission computed tomography (SPECT), 2-D echocardiography and coronary angiography were performed to assess exercise capacity, myocardial perfusion, LV function and coronary anatomy. Intramyocardial injection of autologous CD133+ BMSC cells was safe. No early or long-term complications were observed. After an average of 3.8 weeks from cell inoculation, all patients experienced a significant improvement of CCS class (from 3.8 to 1.8 at 6 months) and serial SPECT documented improvements of rest and stress perfusion in the injected territories at 6 months from operation. In 3 cases, coronary angiography showed an increase in the collateral score of the target areas. Clinical improvements still persist unchanged in 4 out of 5 cases at a mean of 36.5 months postoperatively. After stand-alone BMSC transplantation for refractory myocardial ischemia, we observed long-term clinical and perfusion improvements in the absence of adverse events.

Bone mineral density and single photon emission computed tomography changes after total knee arthroplasty: a 2‐year follow‐up study

Dual X-ray absorptionmetry (DXA) provides a highly reproducible method for quantitative analysis and monitoring periprosthetic bone mineral density (BMD) after total knee arthroplasty (TKA). Single photon emission computed tomography (SPECT) with bone avid radiopharmaceuticals reflects bone metabolic activity and circulation. We combined information from DXA and SPECT to assess the evaluation of the dynamic balance between BMD and bone turnover. Sixteen patients underwent serial DXA (Lunar Expert XL) and 99mTc-methylene diphosphonate SPECT measurements until 2 years after TKA. A rapid bone loss, up to 25.5%, was detected in femur during the first six postoperative months. However, tibial periprosthetic BMD remained close to baseline. There was a significant correlation between 12-month SPECT uptake and preceding BMD change in medial tibia (r = 0.5, P = 0.044). At 12 months, SPECT uptakes in the operated knee were notably higher compared with those of the control knee. SPECT uptakes showed statistically significant decreases from 12 months to 24 months, while SPECT uptake in the control knee remained stable. In tibia, the results are more complex; referring that increased bone remodelling is continuing below the tibial tray. Furthermore, femoral diaphyseal uptake remained elevated, while corresponding tibial uptake had levelled off at 2 years. Increased SPECT uptake during the first 2 years after uncomplicated TKA results most likely from normal postoperative bone remodelling. Levelling of SPECT uptake may indicate a new balance between bone loss and regain.

Crossed Cerebellar Diaschisis in Acute Ischemic Stroke: A Study with Serial SPECT and MRI

This study evaluated the relationship between crossed cerebellar diaschisis (CCD) and (1) lesion volume and location in the acute phase and 1 week after stroke onset and (2) clinical outcome. Twenty-two patients with cerebral ischemic stroke underwent single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) within 48 h and on day 8 from onset. Interhemispheric asymmetric indices (AI) on SPECT were calculated for medial, intermediate, and lateral zones of the cerebellum. Lesion volumes and locations were obtained from diffusion-weighted MRI. Neurological status and 3-month clinical outcome were evaluated. Within 48 h, lesion locations in the temporal association cortex and pyramidal tract of the corona radiata were independent determinants for the AI of the medial zone (R(2)=0.439). Lesion locations in the primary, premotor, and supplementary motor cortices, primary somatosensory cortex, and anterior part of the posterior limb of the internal capsule were determinants for the AI of the intermediate zone (R(2)=0.785). Lesions in the primary motor cortex, premotor, and supplementary motor cortices and in the genu of the internal capsule were determinants for the AI of the lateral zone (R(2)=0.746). On day 8, the associations were decreased. The AIs of the intermediate and lateral zones and lesion location in the parietal association cortex were independently associated with the 3-month clinical outcome (R(2)>0.555). Acute CCD is a result of functional deafference, while in the subacute phase, transneuronal degeneration might contribute to CCD. CCD in the intermediate and later zones is a better indicator than that in the medial zone.

123I-IMT SPECT for evaluation of the response to radiation therapy in high grade gliomas: a feasibility study

Assessing response to radiation therapy in patients with high grade gliomas is needed upon making decisions toward further therapy strategies. Currently used standard imaging tools such as CT and MRI are not sensitive enough to detect early therapy effects. We prospectively investigated if single photon emission computed tomography (SPECT) using radiolabelled amino acid derivate (123)I-methyltyrosine (IMT) would be useful for this aim. 10 patients with histologically proven high grade gliomas, who were candidates for radiation therapy, were enrolled in this investigation. All patients were examined by IMT SPECT before radiation therapy and 4 weeks after the initiation of the hypofractionated application of 40 Gy. Patients were followed up for 39 months; the tumours to background ratios (T/B) for IMT under/before radiation therapy were correlated to survival times. Initially, SPECT depicted an abnormal intratumoural IMT uptake in all patients (mean T/B ratios 1.37-1.87). In four out of 10 patients, the mean T/B ratios decreased by more than 10% under radiation therapy. In six other patients, the BQ decreased by less than 10% or increased. There were no significant correlations between the degree of changes in T/B and survival (r = -0.1, p = 0.973). Serial IMT SPECT measurements allow detection of changes in amino acid accumulation in high-grade gliomas under radiation therapy. However, these changes seem to possess no prognostic value in respect to survival prediction.

Brain serotonin transporter availability predicts treatment response to selective serotonin reuptake inhibitors

Few studies have investigated the predictive value of central serotonin transporter (SERT) availability for treatment response to serotonin reuptake inhibitors (SSRIs). This study used brain imaging to examine the relationship between pretreatment brain SERT availability and transporter occupancy by SSRIs with treatment response in two independent depressed populations. Study 1: Twenty-three patients with major depression underwent a single photon emission computed tomography (SPECT) measurement of brain SERT availability using [123I]beta-CIT ([123I]methyl 3beta-(4-iodophenyl) tropane-2beta-carboxylate. The SERT availability was correlated with treatment response to fluoxetine (20 mg/day) assessed with weekly Hamilton Depression Rating Scale (HDRS) for 6 weeks. Study 2: The second group included 10 depressed patients who received 6 weeks of paroxetine treatment (20 mg/day) and serial SPECT scans (baseline, during, and after the treatment). In Study 1, higher pretreatment diencephalic SERT availability significantly predicted better treatment response 4 weeks later. Similar results were found in Study 2 and supported Study 1 findings. The data showed that greater occupancy of diencephalic transporters by paroxetine correlated with better treatment response. Higher pretreatment availability and greater occupancy of SERT in diencephalon may predict better treatment course in response to SSRIs.

Modelling of cardiac imaging data with spatial correlation.

Cardiac imaging with single photon emission computed tomography (SPECT) is a common approach for quantifying myocardial perfusion. Fusing serial SPECT studies allows detection and quantification of changes in myocardial perfusion such as those resulting from disease progression or successful treatment therapy for patients with coronary artery disease. The abundance of data for each subject along with the inherent intra-subject correlation due to spatial proximity of multiple perfusion measurements present special analytical challenges. We utilize a standard physiological model of the left ventricle (LV) to construct a general statistical model for cardiac perfusion that incorporates spatial correlation. We illustrate the use of mixed effects models and linear models with correlated errors to estimate myocardial perfusion counts and to compare these counts across serial studies. We address different types of spatial correlation among perfusion measurements in the LV, and we consider various parametric structures for these correlations. We apply the model to data from serial SPECT studies conducted while subjects were in both restful and stressful states approximately two days and one year following a myocardial infarction.

Variability of serial same-day left ventricular ejection fraction using quantitative gated SPECT

Background. The accuracy of quantitative gated single photon emission computed tomography (SPECT) (QGS) and the potential limitations for estimation of left ventricular ejection fraction (LVEF) have been extensively evaluated. However, few studies have focused on the serial variability of QGS. This study was conducted to assess the serial variability of QGS for determination of LVEF between 2 sequential technetium 99m sestamibi–gated SPECT acquisitions at rest in both healthy and unhealthy subjects. Methods and Results. The study population consisted of 2 groups: group I included 21 volunteers with a low likelihood of CAD, and group II included 22 consecutive patients with documented CAD. Both groups underwent serial SPECT imaging. The overall correlation between sequential images was high (r = 0.94, SEE = 5.3%), and the mean serial variability of LVEF was 5.15% ± 3.51%. Serial variability was lower for images with high counts (3.45% ± 3.23%) than for images with low counts (6.85% ± 3.77%). The mean serial variability was not different between normal and abnormal high-dose images (3.0% ± 1.56% vs 3.9% ± 2.77%). However, mean serial variability for images derived from abnormal low-dose images was significantly greater than that derived from normal low-dose images (9.6% ± 2.22% vs 3.1% ± 2.12%, P < .05). Conclusions. Although QGS is an efficacious method to approximate LVEF values and is extremely valuable for incremental risk stratification of patients with coronary artery disease, it has significant variability in the estimation of LVEF on serial images. This should be taken into account when used for serial evaluation of LVEF. (J Nucl Cardiol 2002;9:377-84)

Evaluation of myocardial infarct size in rat heart by pinhole SPECT

Background. High-resolution single photon emission computed tomography (SPECT) with a pinhole collimator is a new method for evaluating the regional properties of radiopharmaceuticals in small laboratory animals in vivo. Although several reports of normal images of rat taken by this new technique are available, there are as yet few reports on its use in disease models, such as myocardial infarction. In this study, we clearly visualized myocardial flow in the rat heart with myocardial infarction using this system, and evaluated the relationship between SPECT images and histologic analysis. Methods and Results. For visualization of myocardial flow in rat heart, 201Tl images were taken just before and 24 days after left coronary artery ligation. The images were taken using a 4-head SPECT scanner with pinhole collimators. The percent infarct size on 201Tl-SPECT imaging (%SI) and the defect score were then assessed and compared with the percent infarct size on histologic analysis (%HI). Both the %SI and defect score correlated well with %HI ( r= 0.97 and 0.74, respectively). Conclusion. Serial SPECT imaging using pinhole collimators permits estimates of myocardial flow even in small laboratory animals noninvasively in vivo.

A single photon emission computed tomography study of cerebral regional perfusion changes induced by a learning task in subjects with mild memory impairment

Fifteen nondemented subjects with memory complaints underwent serial single photon emission computed tomography (SPECT) studies with technetium-99m- d,l-hexamethyl-propylene amine oxime (HMPAO) as tracer. Scans were carried out under a baseline condition and during the learning phase of the Memory Efficiency Profile (MEP), a combined visual perception and memory task developed by Rey. Results indicate a positive correlation between activation, as indexed by HMPAO uptake, and neuropsychological assessment. Right temporal activation was correlated with MEP immediate recall. The right cerebellum was correlated with both MEP immediate and delayed recall. This study suggests that SPECT can show cortical activation during cognitive performance in subjects with mild memory impairment.

Grafted bone used in acetabular reconstruction: assessment by SPECT scintigraphy.

To investigate incorporation of the grafted bone used for acetabular reconstruction. Single photon emission computed tomography (SPECT) was carried out at the 1st, 6th, and 12th month after the operation and the uptakes on serial SPECT scintigrams were normalized. The horizontal histogram of scintigraphic activity at the level of the central grafted bone in the coronal image was designated the profile curve. Seven patients who had undergone bipolar hip arthroplasty for osteoarthritis of the hip were randomly selected. Five of seven profile curves obtained at the 1st month demonstrated a single peak at the host-graft junction. The profile curve obtained at the 6th month showed two peaks at the host-graft junction and the periphery of the grafted bone in all patients. The profile curve at the 12th month showed slightly increased activity in the center of the grafted bone. This preliminary study demonstrates that comparison of the serial profile curves on SPECT is valuable in evaluating the progress of incorporation of the grafted bone in hip arthroplasty.

Contribution of Diaschisis to the Clinical Deficit in Human Cerebral Infarction

Regions of decreased cerebral blood flow are often seen on single-photon emission computed tomography (SPECT) after stroke and have been widely reported to add to the clinical deficit. However, such reports have not distinguished between correlation and causation. We analyzed 124 serial SPECT scans performed in 50 patients to assess the role of diaschisis in the clinical deficit after stroke. SPECT with the use of 99mTc-hexamethylpropyleneamine oxime (99mTc-HMPAO) was performed in a prospective, unselected series of 50 patients with cerebral infarcts studied at a median of 1.1, 6.8, and 95 days after ictus. Patients were also assessed with the use of the Canadian Neurological Scale, the Barthel Index, a neuropsychological evaluation, and infarct volume measurement. One hundred twenty-four serial SPECT scans were done in 50 patients. Diaschisis was identified at 168 sites. There was insufficient correlation between diaschisis and the clinical measurements to support the suggestion that diaschisis independently causes clinical deficits beyond those due to the infarct itself. Unlike the clinical status, diaschisis showed little tendency to resolve during the 3-month follow-up period of the study. Several of the instances of correlation were shown to be of a noncausal kind, with both the diaschisis and the clinical deficit being due to the lesion directly; there was no known mechanism for the diaschisis to cause the clinical deficit. Diaschisis does not independently add to the clinical deficit after stroke. It is more likely that it simply represents part of the damage done by the stroke.

Asymmetrical blood flow in the temporal lobe in the Charles Bonnet syndrome: serial neuroimaging study.

Clinical features and results of neuroimagings of an 86 year old woman with the Charles Bonnet syndrome are reported. She had become completely blind bilaterally due to cataracts and glaucoma. Shortly after an operation for cataracts, she developed visual hallucinations which lasted for 22 years. She had no deterioration of intelligence. Computed tomography (CT) and magnetic resonance imaging (MRI) showed moderate generalized atrophy, particularly of the temporal lobes. A serial single photon emission computed tomography (SPECT) study during visual hallucinations demonstrated hyperperfusion in the left temporal region and the basal ganglia and hypoperfusion in the right temporal region. These findings suggest that asymmetrical blood flow, particularly in the temporal regions, may be correlated with visual hallucination in the Charles Bonnet syndrome.

Asymmetrical Blood Flow in the Temporal Lobe in the Charles Bonnet Syndrome: Serial Neuroimaging Study

Clinical features and results of neuroimagings of an 86 year old woman with the Charles Bonnet syndrome are reported. She had become completely blind bilaterally due to cataracts and glaucoma. Shortly after an operation for cataracts, she developed visual hallucinations which lasted for 22 years. She had no deterioration of intelligence. Computed tomography (CT) and magnetic resonance imaging (MRI) showed moderate generalized atrophy, particularly of the temporal lobes. A serial single photon emission computed tomography (SPECT) study during visual hallucinations demonstrated hyperperfusion in the left temporal region and the basal ganglia and hypoperfusion in the right temporal region. These findings suggest that asymmetrical blood flow, particularly in the temporal regions, may be correlated with visual hallucination in the Charles Bonnet syndrome.

Incorporation of allograft for acetabular reconstruction. Single photon emission CT in 21 hip arthroplasties followed for 2.5-5 years.

We studied 21 hips in 20 patients who had acetabular reconstruction with a femoral head allograft in primary (n 2) and secondary (n 19) total hip arthroplasty. The fate of the graft was evaluated by serial bone SPECTs (single photon emission computed tomography). With a mean follow-up period of 37 (30-60) months, 14 of the 21 hips showed evidence of incorporation at earliest 13 (6-18) months after operation. There was no correlation between the fate of allograft and the compatibility of A, B, O blood typing between host and donor, the use of bone cement in the fixation of acetabular component, or loosening of the acetabular component.