Torbjörn Sundström

Altered cerebral blood flow in chronic neck pain patients but not in whiplash patients: a 99mTc-HMPAO rCBF study.

A cross-sectional study to investigate regional cerebral blood flow (rCBF) in patients with chronic whiplash syndrome and chronic neck pain patients without previous history of trauma along with a healthy control group. Chronic neck pain is a common disorder and a history of cervical spine injury including whiplash trauma constitute a risk factor for persistent neck pain. The aetiology of the late whiplash syndrome is unknown with no specific diagnostic criteria based on imaging, physiological, or psychological examination. Earlier studies indicate a parieto-occipital hypoperfusion but it is unclear if the hypoperfusion represents a response to chronic pain. The rCBF was monitored in 45 patients with chronic neck pain: 27 cases with chronic whiplash syndrome and 18 age and gender matched cases with non-traumatic chronic neck pain. The rCBF was estimated with single-photon emission computed tomography (SPECT) using technetium-99m hexamethylpropylene amine oxime (HMPAO). The non-traumatic patients displayed rCBF changes in comparison with the whiplash group and the healthy control group. These changes included rCBF decreases in a right temporal region close to hippocampus, and increased rCBF in left insula. The whiplash group displayed no significant differences in rCBF in comparison with the healthy controls. The present study suggests different pain mechanisms in patients with chronic neck pain of non-traumatic origin compared to those with chronic neck pain due to a whiplash trauma.

99mTc-DPD uptake reflects amyloid fibril composition in hereditary transthyretin amyloidosis

Abstract Aims In transthyretin amyloid (ATTR) amyloidosis various principal phenotypes have been described: cardiac, neuropathic, or a mixed cardiac and neuropathic. In addition, two different types of amyloid fibrils have been identified (type A and type B). Type B fibrils have thus far only been found in predominantly early-onset V30M and in patients carrying the Y114C mutation, whereas type A is noted in all other mutations currently examined as well as in wild-type ATTR amyloidosis. The fibril type is a determinant of the ATTR V30M disease phenotype. 99mTc-DPD scintigraphy is a highly sensitive method for diagnosing heart involvement in ATTR amyloidosis. The objective of this study was to determine the relationship between ATTR fibril composition and 99mTc-DPD scintigraphy outcome in patients with biopsy-proven ATTR amyloidosis. Methods Altogether 55 patients with biopsy-proven diagnosis of ATTR amyloidosis and amyloid fibril composition determined were examined by 99mTc-DPD scintigraphy. The patients were grouped and compared according to their type of amyloid fibrils. Cardiovascular evaluation included ECG, echocardiography, and cardiac biomarkers. The medical records were scrutinized to identify subjects with hypertension or other diseases that have an impact on cardiac dimensions. Results A total of 97% with type A and none of the patients with type B fibrils displayed 99mTc-DPD uptake at scintigraphy (p < 0.001). Findings from analyses of cardiac biomarkers, ECG, and echocardiography, though significantly different, could not differentiate between type A and B fibrils in individual patients. Conclusion In ATTR amyloidosis, the outcome of 99mTc-DPD scintigraphy is strongly related to the patients’ transthyretin amyloid fibril composition.

Subcentimeter Tumor Lesion Delineation for High-Resolution 18F-FDG PET Images: Optimizing Correction for Partial-Volume Effects

In PET, partial-volume effects cause errors in estimation of size and activity for small objects with radiopharmaceutical uptake. Recent methods for image reconstruction, compared with traditional reconstruction techniques, include algorithms for resolution recovery that result in images with higher resolution and enable quantification of size and activity of smaller objects. The purpose of this study was to evaluate a combination of 2 algorithms for volume delineation and partial-volume correction on uptake volumes smaller than 0.7 mL using image reconstruction algorithms with and without resolution recovery. Methods: Volumes of interests (VOIs) were delineated using a threshold intensity calculated as a weighted sum of tumor and background intensities. These VOIs were used for calculating correction factors by convolving a tumor mask with the system point-spread function. The methods algorithms were evaluated using a phantom constructed from 5 small different-sized balloons filled with 18F-FDG in background activity. Six different backgrounds were used. Data were acquired using a PET/CT scanner, and the images were reconstructed using 2 iterative algorithms, one of which used a resolution recovery algorithm. Results: For the images reconstructed using the resolution recovery algorithm, the method for volume delineation resulted in VOI sizes that were correct within 1 SD for all balloons of a volume of 0.35 mL (equivalent diameter, 8.8 mm) and larger, in all backgrounds. For the images reconstructed without resolution recovery, the VOI sizes were background-dependent and generally less accurate. Correct volume delineations generally led to accurate activity estimates. Conclusion: The algorithms tested on the phantom developed for this study could, for this PET camera and these reconstruction algorithms, be used for accurate volume delineation and activity quantification of lesions 0.35 mL and larger.

Detecting Small Liver Tumors With

In 111In-pentetreotide single-photon emission computed tomography (SPECT), the tumor-to-background-uptake ratio is generally high. The noise is, however, also usually on a high level, and in combination with the low spatial resolution of SPECT, this may lead to difficulties in the detection of small tumors. This is especially the case in regions with a relatively high background activity, such as in the liver, which is a common region for somatostatin-positive metastases. Visually detecting the small tumors is important for a successful treatment of the cancer disease. In this paper, we compare three different parallel-hole collimators for 111In-pentetreotide SPECT regarding contrast as a function of image noise for a phantom simulating small tumors in liver background. The corresponding contrast-to-noise ratios are also presented. All raw-data projections are produced using Monte Carlo simulations. The collimators are of type low-energy general-purpose (LEGP), extended LEGP (ELEGP), and medium-energy general-purpose (MEGP). Reconstructions were performed with OSEM both with and without model-based compensation. Of the investigated collimators, the ELEGP collimator proved to be the most optimal for the smallest tumors, both with and without model-based compensation included in the reconstruction. It is also shown that model-based compensation outperforms the conventional reconstruction technique.

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Previously we have investigated a depth-independent compensation for collimator detector response (CDR) included in the OSEM reconstruction, intended for SPECT images that have been corrected for scatter and septal penetration using convolution-based methods. In this work, the aim was to study how different filtering strategies affect contrast as a function of noise when using Gaussian smoothing filters in combination with the above-described CDR compensation. The evaluation was performed for (123)I dopamine transporter (DAT) SPECT images. Prefiltering with 2D Gaussian filter kernels, where the deterioration in resolution is included in the depth-independent CDR compensation, was compared to conventional postfiltering with 3D Gaussian filter kernels. Images reconstructed without filtering are also included in the comparison. It was found that there is little benefit in noise reduction when using CDR compensation. However, this variant of prefiltering gives consistently higher contrasts as a function of noise compared with the postfiltering alternative, and that could be of interest when using other types of filters with contrast improving properties.

In-Pentetreotide SPECT—A Collimator Study Based on Monte Carlo Simulations

PurposeAlzheimer’s disease (AD) is a primary degenerative disease that progressively affects all brain functions, with devastating consequences for the patient, the patient’s family and society. Rest regional cerebral blood flow (rCBF) could have a strategic role in differentiating between AD patients and normal controls, but its use for this purpose has a low discriminatory capacity. The purpose of this study was to evaluate whether the diagnostic sensitivity of rCBF single-photon emission computed tomography (SPECT) could be increased by using an episodic memory task provocation, i.e. memory-provoked rCBF-SPECT (MP-SPECT).MethodsEighteen persons (73.2±4.8 years) with mild AD and 18 healthy elderly (69.4±3.9 years) were included in the study. The subjects were injected with 99mTc-hexamethylpropylene amine oxime (HMPAO) during memory provocation with faces and names, followed by an rCBF-SPECT study. The rCBF 99mTc-HMPAO SPECT images were analysed using statistical parametric mapping (SPM2). Peaks with a false discovery rate corrected value of 0.05 were considered significant.ResultsOn MP-SPECT, the AD group showed a significant rCBF reduction in the left parietal cortex in comparison with healthy elderly. At rest, no significant group differences were seen.ConclusionMemory provocation increased the sensitivity of rCBF-SPECT for the detection of AD-related blood flow changes in the brain at the group level. Further studies are needed to evaluate MP-SPECT as a diagnostic tool at the individual level. If a higher sensitivity for AD at the individual level is verified in future studies, a single MP-SPECT study might be sufficient in the clinical setting.

Gaussian prefiltering of 123I DAT SPECT images when using depth-independent resolution recovery

Background DPD scintigraphy has been advocated for imaging cardiac amyloid in ATTR amyloidosis. PET utilizing 11C-Pittsburgh compound B (PIB) is the gold standard for imaging brain amyloid in Alzheimer’s disease. PIB was recently shown to identify cardiac amyloidosis in both AL and ATTR amyloidosis. In the ATTR population, two types of amyloid fibrils exist, one containing fragmented and full-length TTR (type A) and the other only full-length TTR (type B). The aim of this study was to further evaluate PIB-PET in patients with hereditary ATTR amyloidosis.

Memory-provoked rCBF-SPECT as a diagnostic tool in Alzheimer's disease?

BackgroundRadiation treatment with simultaneous integrated boost against suspected lymph node metastases may be a curative therapeutic option in patients with high-risk prostate cancer (>15% estimated risk of pelvic lymph node metastases according to the Cagiannos nomogram). 11C-acetate positron emission tomography/computed tomography (PET/CT) can be used for primary staging as well as for detection of suspected relapse of prostate cancer. The aims of this study were to evaluate the association between positive 11C-acetate PET/CT findings and the estimated risk of pelvic lymph node metastases and to assess the impact of 11C-acetate PET/CT on patient management in high-risk prostate cancer patients.MethodsFifty consecutive prostate cancer patients referred for primary staging with 11C-acetate PET/CT prior to radiotherapy with curative intention were enrolled in this retrospective study.ResultsAll patients showed increased 11C-acetate uptake in the prostate. Pelvic lymph node uptake was seen in 42% (21/50) of the patients, with positive external iliac lymph nodes in 71% (15/21) of these. The overall observed proportion of PET/CT-positive pelvic lymph nodes at patient level was higher than the average estimated risk, especially in low-risk groups (<15%). There was a significant association between observed proportion and estimated risk of pelvic lymph node metastases in groups with ≤45 and >45% estimated risk. Treatment strategy was altered due to 11C-acetate PET/CT findings in 43% (20/47) of the patients.ConclusionsThe observed proportion of 11C-acetate PET/CT findings suggestive of locoregional metastases was higher than the estimated risk, suggesting that the Cagiannos nomogram underestimates the risk for metastases. The imaging results with 11C-acetate PET/CT have a considerable impact on patient management.

Positron Emission Tomography (PET) utilizing Pittsburgh compound B (PIB) detects amyloid heart deposits in hereditary transthyretin amyloidosis (ATTR).

Abstract Objectives: To compare cumulative ionizing radiation in patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) for the years 2001–2011. To study how radiation exposure change over time in patients with newly diagnosed IBD and factors associated with radiation exposure. Material and methods: All radiological investigations performed between 1 January 2001 and 31 December 2011 were retrospectively recorded in patients with Crohn’s disease (CD) (n = 103), ulcerative colitis (UC) (n = 304) and IBS (n = 149). Analyses were done with Mann–Whitney and Chi-Square test. Results: The median total cumulative radiation exposure in mSv for CD (20.0, inter quartile range (IQR) 34.8), UC (7.01, IQR 23.8), IBS (2.71, IQR 9.15) and the proportion of patients who had been exposed for more than 50 mSv during the study period (CD 19%, UC 11%, IBS 3%) were significantly higher in the patients with CD compared to patients with UC (p < .001) and IBS (p < .001), respectively. In turn, patients with UC had significantly higher doses than patients with IBS (p = .005). Risk factors for radiation exposure were female gender (CD), early onset (UC), ileocolonic location (CD), previous surgery (CD and UC), depression (IBS) and widespread pain (IBS). In newly diagnosed CD, there was a significant decline in median cumulative radiation dose in mSv (17.2 vs. 12.0; p = .048) during the study period. Conclusions: Patients with CD are at greatest risk for high cumulative radiation exposure, but there is a decline in exposure during the late 2000s. Non-colectomized patients with UC and patients with IBS have a relatively low risk of cumulative radiation exposure.

11 C-acetate PET/CT in pre-therapeutic lymph node staging in high-risk prostate cancer patients and its influence on disease management - a retrospective study

In 111In-pentetreotide SPECT, it can be difficult to detect small tumors because of high noise levels and low spatial resolution. The aim of this study was to perform optimization of tumor detection in the liver, with regards to the acquisition and reconstruction protocol for 111In-pentetreotide SPECT with model-based compensation included in the OSEM reconstruction. We were also interested in the effect of performing the examination in half of the time or with half the administered activity. Image reconstruction without model-based compensation was also included for comparison. The study concentrates on the acquired number of projections and the subset size in the OSEM reconstruction, and evaluates contrast as a function of noise for a range of OSEM iterations. The raw-data projections are produced using Monte Carlo simulations of a patient-like anthropomorphic phantom with realistic 111ln-pentetreotide uptake, including spherical tumors in the liver. Two collimators are evaluated, the extended low-energy general-purpose (ELEGP) and the medium-energy general-purpose (MEGP) collimator. ELEGP proved to be a better collimator when using model-based compensation. The results also indicate that a relatively low number of subsets is advantageous, and that 60 projection angles or even lower is a better choice than 120. For both collimators the time-reduced scan including model-based compensation was better compared to the full-time reconstructions without model-based compensation.