Discordance between labelled white blood cell scintigraphy and bone scan following suspicion of bone infection: what should be done about it?

BACKGROUND: Bone infection is a common issue in infectiology. The gold standard for evaluating bone infection is the white blood cell (WBC) scan. In our practice the WBC scan is coupled with a bone scan. Discordances in the results of these two examinations are a common occurrence in daily practice. We decided to investigate the meaning of these discordances. MATERIALS AND METHODS: Two hundred and ninety-six 99mTc-HMPA labelled white blood cells (WBC) and 99mTc-HMDP bone scanning (BS) examinations were performed in our department between 1997 and 2003 for evaluation of bone infection. Out of these 296 examinations, a first rating extracted 54 scans that were considered discordant. These 54 scans were reviewed by three observers. Clinical and paraclinical data were obtained for all the cases definitely considered as discordant by all three observers. RESULTS: The observers finally retained 18 cases as discordant from the initial 296 (6.1%). Thirteen patients were not infected,and five patients were considered infected based on clinical follow-up or bacteriological and histological data. For the 17 patients with WBC-, BS+, 4 (23.5%) were infected. CONCLUSION: Our study shows that in the vast majority(17 out of 18), discordances consist of a negative WBC scan with a positive bone scan. In these cases the accuracy of the WBC scan is diminished as 23.5% of the patients with a negative WBC and a positive bone scan are infected.

Sensory alien hand syndrome in corticobasal degeneration: a cerebral blood flow study.

The presence of alien hand syndrome (AHS) is suggestive of the diagnosis of corticobasal degeneration when it develops in a progressive way. Sensory AHS (sAHS) should be distinguished from the motor form described more commonly. The physiopathology of sAHS remains unclear. The aim of this study is to determine cerebral regions involved in sAHS. We compared perfusion single photon emission computer tomography scans of patients with sAHS (n = 3) and without (n = 4). We observed significant decrease of regional cerebral blood flow over the nondominant thalamus in sAHS+ compared to sAHS- patients. This result suggests the involvement of the nondominant thalamus in sAHS.

Cerebral hemodynamic changes in severe head injury patients undergoing decompressive craniectomy.

OBJECTIVE: To assess the intracranial hemodynamic modifications induced by a decompressive craniectomy (DC) after severe traumatic brain injury (TBI), using transcranial Doppler (TCD) ultrasonography and intracranial pressure (ICP) sensor. Mortality rate and neurological outcomes were also evaluated after this procedure. DESIGN: A prospective study was carried out on 26 TBI patients, measuring transcranial Doppler and ICP before, immediately after, and 48 hours after the DC, allowing for statistical analysis of hemodynamic changes. The mortality rate and the neurological outcomes were assessed. MEASUREMENTS AND RESULTS: After DC, ICP decreased from 37+/-17 to 20+/-13 mm Hg (P=0.0003). The global cerebral blood flow was modified with diastolic velocities rising from 23+/-15 to 31+/-13 cm/s (P=0.0038) and a pulsatility index decreasing from 1.70+/-0.66 to 1.18+/-0.37 (P=0.0012). This normalization of the global cerebral hemodynamics after the DC was immediate, symmetric, and constant during the first 48 hours. Outcome was evaluated at 6 months: good recovery or moderate disability was observed in 11 patients (42%), persistent vegetative state in 7 patients (27%), and 8 patients died (31%). CONCLUSIONS: The DC results in a significant, immediate, and durable improvement of ICP associated with a normalization of cerebral blood flow velocities in most TBI patients with refractory intracranial hypertension.

Iterative three-dimensional expectation maximization restoration of single photon emission computed tomography images: application in striatal imaging.

Single photon emission computed tomography imaging suffers from poor spatial resolution and high statistical noise. Consequently, the contrast of small structures is reduced, the visual detection of defects is limited and precise quantification is difficult. To improve the contrast, it is possible to include the spatially variant point spread function of the detection system into the iterative reconstruction algorithm. This kind of method is well known to be effective, but time consuming. We have developed a faster method to account for the spatial resolution loss in three dimensions, based on a postreconstruction restoration method. The method uses two steps. First, a noncorrected iterative ordered subsets expectation maximization (OSEM) reconstruction is performed and, in the second step, a three-dimensional (3D) iterative maximum likelihood expectation maximization (ML-EM) a posteriori spatial restoration of the reconstructed volume is done. In this paper, we compare to the standard OSEM-3D method, in three studies (two in simulation and one from experimental data). In the two first studies, contrast, noise, and visual detection of defects are studied. In the third study, a quantitative analysis is performed from data obtained with an anthropomorphic striatal phantom filled with 123-I. From the simulations, we demonstrate that contrast as a function of noise and lesion detectability are very similar for both OSEM-3D and OSEM-R methods. In the experimental study, we obtained very similar values of activity-quantification ratios for different regions in the brain. The advantage of OSEM-R compared to OSEM-3D is a substantial gain of processing time. This gain depends on several factors. In a typical situation, for a 128 x 128 acquisition of 120 projections, OSEM-R is 13 or 25 times faster than OSEM-3D, depending on the calculation method used in the iterative restoration. In this paper, the OSEM-R method is tested with the approximation of depth independent resolution. For the striatum this approximation is appropriate, but for other clinical situations we will need to include a spatially varying response. Such a response is already included in OSEM-3D.

A SPECT study of wandering behavior in Alzheimer's disease.

BACKGROUND: Among behavior disturbance during Alzheimer's disease (AD), wandering is one of the most common. Different psychological processes have been suggested to explain the wandering behavior. The aim of this study was to examine whether wandering during AD was associated with cerebral perfusion patterns measured by (99 m)Tc-labeled bicisate (ECD) brain SPECT. METHODS: We compared SPECT scans of 13 AD subjects with wandering behavior (sex ratio M/F, 4/9; age, 73.1 years, SD 7.4; Mini Mental Status Examination score, median 20 interquartile range [16-23]), 13 AD subjects without wandering behavior (matched for age [ +/- 2 years], sex and MMSE score [ +/- 2 points]) and 13 healthy controls (matched for age [ +/- 2 years] and sex) without cognitive impairment. Wandering was defined on the Neuro-Psychiatric Inventory. Score of leukoaraiosis, assessed with the scale of Blennow and number of lacuna infarction were compared on CT scan. SPECT imaging was compared using statistical parametric mapping (SPM 2). RESULTS: There were no significant differences between the groups in term of educational level and CT scan analysis. SPECT imaging was consistent with the diagnosis of AD in both wanderers and AD subjects without wandering behavior. Despite similar clinical dementia severity, wanderers had more severely reduced regional cerebral blood flow (rCBF) in the left parietal-temporal lobe than AD subjects without wandering behavior. CONCLUSION: Wandering behavior could be facilitated by a specific patterns of cerebral blood flow. Wandering, as a physical activity, could also enhance the recruitment of the cortical network.

Effectiveness of lymphoscintigraphic sentinel node detection for cervical staging of patients with squamous cell carcinoma of the head and neck.

PURPOSE: To evaluate the feasibility and staging ability of the sentinel node (SN) technique for patients with squamous cell carcinoma of the oral cavity or oropharynx and clinically negative necks. This prospective study compares the histopathologic status of the SN with that of the remaining neck dissection tissues. PATIENTS AND METHODS: Thirty previously untreated patients with T1 to T4 squamous cell carcinoma of the oral cavity or oropharynx and clinically negative necks (N0) were included in the study. Injection of 99m Tic-radiolabeled sulfur colloid around the primary tumor and lymphoscintigraphy were performed the day before surgery. Intraoperatively, the SN(s) was localized with a gamma probe and removed during neck dissection. The tumor was resected at the same time. RESULTS: For 1 patient, lymphoscintigraphy revealed no SN. SN were identified in 29 patients/37 necks. In 29 necks, there were no positive SN. In 5 patients, the SN was the only histopathologically positive node. In 1 patient, SN and other nodes in the remaining neck tissue were positive. There was 1 false negative case; the first case of the study, indicating the need for a learning curve for the technique. CONCLUSION: This prospective study shows that the SN is useful for the staging of N0 necks. The SN technique has the potential to decrease the need for neck dissections, which are usually performed in clinically negative necks, thus reducing both associated morbidity for patients and cost.

Multimodal image registration for localization of sentinel nodes in head and neck squamous cell carcinoma.

PURPOSE: The aim of this clinical study was to propose a new method of preoperative 3-dimensional localization of the neck sentinel node in clinically and radiographically N0 squamous cell carcinoma of the oral cavity. PATIENTS AND METHODS: This prospective study was carried out between August 2002 and August 2003. Ten patients with staged oral squamous cell cancer underwent this method of preoperative localization of the sentinel lymph node. At the present time, lymphoscintigraphy is recognized as the investigation of choice for the preoperative detection of sentinel nodes. Although we found it to be highly sensitive (100% in our study), it does not allow precise localization of the sentinel node in the anatomic context of the neck. To overcome this drawback, we used multimodal image registration applied to the cervical region in association with the imaging modalities of scintigraphy (single-photon emission computed tomography [SPECT] and gamma transmission) and computed tomography (CT). SPECT and gamma transmission (barium-133 sources) were carried out with a triple-head Philips-Marconi camera (Philips Medical System, Cleveland, OH), and CT was carried out with a General Electric console (GE Medical Systems, Milwaukee, WI). Gamma transmission was used to place the SPECT images in a reference cervical anatomic context (CT images). Registration involved the use of a manual method based on definition of homologous volume structures. RESULTS: Preoperative image registration effectively localized the cervical sentinel node in 9 of the 10 patients, enabling a guided surgical approach in 90% of cases. The sentinel node was localized and resected using a hand-held gamma probe. CONCLUSIONS: This original study adapts a new tool (multimodal image registration) to obtain precise preoperative localization of the cervical sentinel node in N0 oral squamous cell carcinoma. We confirmed the feasibility of this method in this indication. Although this method is a novel one, we believe that it will become extremely useful once a consensus has been reached on exclusive excision of the cervical sentinel node in oral cancers, as is the case for melanoma or breast cancer.

Confirmation by spiral CT of a partially occlusive thrombus of the right pulmonary artery suggested by a V/Q lung scan.

Findings on perfusion and ventilation imaging in a 24-year-old woman with anterior chest pain were consistent with pulmonary embolism involving the right lung. An astute physician raised the possibility of a thrombus occluding the right pulmonary artery, and subsequent spiral computed tomography confirmed the suspicion of an occluding thrombus at that site. Had spiral computed tomography been done first, the diagnosis would have been made much more rapidly.

Quantification of dopamine transporter by 123I-PE2I SPECT and the noninvasive Logan graphical method in Parkinson's disease.

UNLABELLED: (E)-N-(3-iodoprop-2-enyl)-2beta-carbomethoxy-3beta-(4'-methyl-phenyl) nortropane (PE2I), a cocaine analog, is a new, highly specific tracer for imaging dopamine transporter labeled with (123)I for in vivo SPECT. Its reversible binding on dopamine transporter and its rapid kinetics allow quantification of its binding potential according to a 3-compartment model. For quantification of distribution volume of reversible tracer, Logan developed a noninvasive and graphical method that allows accurate estimation of binding potential. In this study, we performed (123)I-PE2I SPECT on healthy volunteers and patients with Parkinson's disease (PD) to validate the Logan graphical method for quantification of (123)I-PE2I binding and to analyze the relationship between (123)I-PE2I SPECT and clinical features of this frequent degenerative disease. METHODS: Eight PD patients (3 women, 5 men; mean age, 64 +/- 7.9 y; disease duration range, 1-8 y, Hoehn and Yahr stage range, 1-2.5) and 8 age-matched healthy volunteers (4 women, 4 men; mean age, 61.5 +/- 9.5 y) were included in 2 centers and studied with SPECT. Four sequential SPECT imaging sessions of 15-min duration were performed from 5 to 65 min after bolus injection of 140 +/- 30 MBq of (123)I-PE2I. RESULTS: The kinetics of PE2I in healthy volunteers and PD patients were rapid, and the Logan graphical method allowed quantification of distribution volume ratio (DVR) in the caudate nucleus and putamen. (123)I-PE2I striatal specific binding was significantly reduced in PD patients, compared with healthy volunteers, in the caudate and putamen. The decrease of DVR in the putamen was significantly and inversely correlated to disease duration and Hoehn and Yahr stage. In asymmetric PD patients, (123)I-PE2I uptake was significantly more reduced in the putamen contralateral to the side with predominant clinical symptoms. However, (123)I-PE2I uptake was also significantly reduced in the ipsilateral putamen, compared with that in healthy volunteers, suggesting that (123)I-PE2I SPECT can detect nigrostriatal degeneration before the appearance of clinical symptoms. CONCLUSION: Our data indicate that the Logan graphical method is accurate for noninvasive quantification of PE2I and that (123)I-PE2I SPECT is a useful quantitative method for accurate estimation of nigrostriatal dopaminergic nerve terminal degeneration. The close relationships between SPECT findings and clinical data suggest that this method is useful for objectively following the progression of PD and for assessing the effect of potential neuroprotective treatments. Finally, our findings suggest that (123)I-PE2I SPECT can be used for preclinical and early diagnosis of PD.

Acupuncture meridians and radiotracers.

Acupuncture is frequently used and in particular for the treatment of pain. One of the cornerstones of its use, at least in Western countries, is the concept of the acupuncture meridian. Yet, their existence has never actually been proven. Recently, a report was published stating that injection of a radiotracer at an acupuncture point allows the visualization of the corresponding meridian in the shape of a radioactive path which is apparent on scintiscans. The present work confirms the appearance of radioactive paths after the injection of a radiotracer at acupuncture points. However, the cross-checks made with the method used (counting the radioactivity of the venous blood, studying radioactivity of the organs which normally take up the tracer, scintiscan study of the complete meridian paths as they are described in traditional Chinese medicine and studying the effect of venous blockade on the observed radioactive paths) show that the radioactive paths in fact correspond to vascular drainage of the radiotracer.