-
1.
An optimized segmentation and quantification approach in microvascular imaging for OCTA-based neovascular regression monitoring.
Wu, S, Wu, S, Feng, H, Hu, Z, Xie, Y, Su, Y, Feng, T, Li, L
BMC medical imaging. 2021;(1):13
Abstract
BACKGROUND Quantification of neovascularization changes in terms of neovascular complex (NVC) acquired from the optical coherence tomography angiography (OCTA) imaging is extremely important for diagnosis and treatment monitoring of proliferative diabetic retinopathy (PDR). However, only few vessel extraction methods have so far been reported to quantify neovascular changes in NVC with proliferative diabetic retinopathy PDR based on OCTA images. METHODS Here we propose an optimized approach to segment blood vessels, which is based on an improved vascular connectivity analysis (VCA) algorithm and combined with morphological characterization and elimination of noise and artifacts. The length and width of vessels are obtained in the quantitative assessment of microvascular network. The feasibility of the proposed method is further studied by a treatment monitoring and statistical analysis process, as we have monitored and statistically analyzed the changes of NVC based on sampled OCTA images of PDR patients (N = 14) after treatment by intravitreal injection of conbercept. RESULTS The proposed method has demonstrated better performance in accuracy compared with existing algorithms and can thus be used for PRD treatment monitoring. Following the PDR treatment monitoring study, our data has shown that from the 1st day to 7th day of treatment, the averaged (arithmetic mean) length of NVC has been substantially shortened by 36.8% (P < 0.01), indicating significant effects of treatment. Meanwhile, the averaged (arithmetic mean) width of NVC from the 1st day to 7th day of treatment has been increased by 10.2% (P < 0.05), indicating that most of the narrow neovascularization has been reduced. CONCLUSION The results and analysis have confirmed that the proposed optimization process by the improved VCA method is both effective and feasible to segment and quantify the NVC with lower noise and fewer artifacts. Thus, it can be potentially applied to monitor the fibrovascular regression during the treatment period. Clinical Trial Registration This trial is registered with the Chinese Clinical Trial Registry (Registered 27 December 2017, http://www.chictr.org.cn , registration number ChiCTR-IPR-17014160).
-
2.
11C-methionine-PET for differentiating recurrent brain tumor from radiation necrosis: radiomics approach with random forest classifier.
Hotta, M, Minamimoto, R, Miwa, K
Scientific reports. 2019;(1):15666
Abstract
Differentiating recurrent brain tumor from radiation necrosis is often difficult. This study aims to investigate the efficacy of 11C-methionine (MET)-PET radiomics for distinguishing recurrent brain tumor from radiation necrosis, as compared with conventional tumor-to-normal cortex (T/N) ratio evaluation. We enrolled 41 patients with metastatic brain tumor or glioma treated using radiation therapy who underwent MET-PET. The area with a standardized uptake value > 1.3 times that of the normal brain cortex was contoured. Forty-two PET features were extracted and used in a random forest classifier and the diagnostic performance was evaluated using a 10-fold cross-validation scheme. Gini index was measured to identify relevant PET parameters for classification. The reference standard was surgical histopathological analysis or more than 6 months of follow-up with MRI. Forty-four lesions were used for the analysis. Thirty-three and 11 lesions were confirmed as recurrent brain tumor and radiation necrosis, respectively. Radiomics and T/N ratio evaluation showed sensitivities of 90.1% and 60.6%, and specificities of 93.9% and 72.7% with areas under the curve of 0.98 and 0.73, respectively. Gray level co-occurrence matrix dissimilarity was the most pertinent feature for diagnosis. MET-PET radiomics yielded excellent outcome for differentiating recurrent brain tumor from radiation necrosis, which outperformed T/N ratio evaluation.
-
3.
Cine MRI assessment of motility in the unprepared small bowel in the fasting and fed state: Beyond the breath-hold.
Khalaf, A, Nowak, A, Menys, A, Marciani, L, Taylor, SA, Spiller, RC, Gowland, PA, Moran, GW, Hoad, CL
Neurogastroenterology and motility. 2019;(1):e13466
Abstract
BACKGROUND The symptoms of functional bowel disorders are common in postprandial but investigations are generally undertaken in the fasted state using invasive procedures. MRI provides a noninvasive tool to study the gastrointestinal tract in an unperturbed, fed state. The aim of this study was to develop a technique to assess small bowel motility from cine MRI data in the unprepared bowel in fasting and fed states. METHODS Fifteen healthy volunteers underwent a baseline MRI scan after which they consumed a 400 g soup. Subjects then underwent a postprandial scan followed by further scans at regular intervals. Small bowel motility was assessed using single-slice bTFE cine MRI. An optimized processing technique was used to generate motility data based on power spectrum analysis of voxel-signal changes with time. Interobserver variability (n = 15) and intra-observer (n = 6) variability were assessed. Changes in the motility index were compared between fasted and immediate postprandial state. KEY RESULTS Excellent agreement between observers was seen across the range of motility measurements acquired, with intraclass correlation coefficient (ICC) of 0.979 (P < 0.0001) and Bland-Altman limits of agreement 95% CI: -28.9 to 45.9 au. Intra-observer variability was low with ICC of 0.992 and 0.960 (2 observers, P < 0.0001). Changes from the fasted to immediately postprandial state showed an average increase of 122.4% ± 98.7% (n = 15). CONCLUSIONS & INFERENCES This optimized technique showed excellent inter and intra observer agreement. It was sensitive to changes in motility induced feeding. This technique will be useful to study contractile activity and regional patterns along the gastrointestinal tract under physiological conditions.
-
4.
Motion Correction of 18F-NaF PET for Imaging Coronary Atherosclerotic Plaques.
Rubeaux, M, Joshi, NV, Dweck, MR, Fletcher, A, Motwani, M, Thomson, LE, Germano, G, Dey, D, Li, D, Berman, DS, et al
Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2016;(1):54-9
Abstract
UNLABELLED Ruptured coronary atherosclerotic plaques commonly cause acute myocardial infarction. It has recently been shown that active microcalcification in the coronary arteries, one of the features that characterizes vulnerable plaques at risk of rupture, can be imaged using (18)F-NaF PET. We aimed to determine whether a motion correction technique applied to gated (18)F-NaF PET images could enhance image quality and improve uptake estimates. METHODS Seventeen patients with myocardial infarction (n = 7) or stable angina (n = 10) underwent (18)F-NaF PET and prospective coronary CT angiography. PET data were reconstructed in 4 different ways: the first was 1 gated bin (end-diastolic phase with 25% of the counts), the second was 4 gated bins (consecutive 25% segments), the third was 10 gated bins (consecutive 10% segments), and the fourth was ungated. Subsequently, with data from either 4 or 10 bins, gated PET images were registered using a local, nonlinear motion correction method guided by the extracted coronary arteries from CT angiography. Global noise levels and target-to-background ratios (TBR) defined on manually delineated coronary plaque lesions were compared to assess image quality and uptake estimates. RESULTS Compared with the reference standard of using only 1 bin of PET data, motion correction using 10 bins of PET data reduced image noise by 46% (P < 0.0001). TBR in positive lesions for 10-bin motion-corrected data was 11% higher than for 1-bin data (1.98 [interquartile range, 1.70-2.37] vs. 1.78 [1.58-2.16], P = 0.0027) and 33% higher than for ungated data (1.98 [1.70-2.37] vs. 1.49 [1.39-1.88], P < 0.0001). CONCLUSION Motion correction of gated (18)F-NaF PET/coronary CT angiography is feasible, reduces image noise, and increases TBR. This improvement may allow more reliable identification of vulnerable coronary artery plaques using (18)F-NaF PET.
-
5.
Quantification of metabolic tumor activity and burden in patients with non-small-cell lung cancer: Is manual adjustment of semiautomatic gradient-based measurements necessary?
Obara, P, Liu, H, Wroblewski, K, Zhang, CP, Hou, P, Jiang, Y, Chen, P, Pu, Y
Nuclear medicine communications. 2015;(8):782-9
-
-
Free full text
-
Abstract
PURPOSE Metabolic tumor burden (MTB) measurements including metabolic tumor volume and total lesion glycolysis have been shown to have prognostic value in non-small-cell lung cancer (NSCLC). The calculation of MTB typically utilizes software to semiautomatically draw volumes of interest around the tumor, which are subsequently manually adjusted by the radiologist to include the entire tumor. The manual adjustment step can be time-consuming and observer-dependent. We compared the agreement of MTB values obtained using the semiautomatic method with and without manual adjustment in NSCLC patients. METHODS This IRB-approved prospective study included 134 patients with histologically proven NSCLC who underwent fluorine-18 fluorodeoxyglucose PET/computed tomography. The MTB of the primary tumor was measured with a semiautomatic gradient-based method without manual adjustment (the semiautomatic gradient method) and with manual adjustment (the manually adjusted semiautomatic gradient method) by two radiologists using the MIM PETedge tool. The paired t-test, Wilcoxon signed-rank test, and concordance correlation coefficient (CCC) were calculated to evaluate the agreement between MTB measures obtained with these two methods, as well as agreement between the two radiologists for each method. RESULTS Maximum standardized uptake value was identical between the two methods. No statistically significant difference was present for peak standardized uptake value, metabolic tumor volume, and total lesion glycolysis values between the two methods (P=0.23, 0.45, and 0.37, respectively). Excellent agreement between the two methods was found in terms of CCC (CCC>0.98 for all measures). Interobserver reliability was excellent for all measures (CCC>0.90). CONCLUSION The semiautomatic gradient-based tumor-segmentation method can be used without the additional manual adjustment step for MTB quantification of primary NSCLC tumors.
-
6.
Semiautomatic region-of-interest validation at the femur in (18)F-fluoride PET/CT.
Puri, T, Blake, GM, Curran, KM, Carr, H, Moore, AE, Colgan, N, O'Connell, MJ, Marsden, PK, Fogelman, I, Frost, ML
Journal of nuclear medicine technology. 2012;(3):168-74
Abstract
UNLABELLED The assessment of regional skeletal metabolism using (18)F-fluoride PET ((18)F-PET) requires segmentation of the tissue region of interest (ROI). The aim of this study was to validate a novel approach to define multiple ROIs at the proximal femur similar to those used in dual x-ray absorptiometry. Regions were first drawn on low-dose CT images acquired as a routine part of the PET/CT study and transferred to the (18)F-PET images for the quantitative analysis of bone turnover. METHODS Four healthy postmenopausal women with a mean age of 65.1 y (range, 61.8-70.0 y), and with no history of metabolic bone disorder and not currently being administered treatment affecting skeletal metabolism, underwent dynamic (18)F-PET/CT at the hip with an injected activity of 180 MBq. The ROIs at the proximal femur included femoral shaft, femoral neck, and total hip and were segmented using both a semiautomatic method and manually by 8 experts at manual ROI delineation. The mean of the 8 manually drawn ROIs was considered the gold standard against which the performances of the semiautomatic and manual methods were compared in terms of percentage overlap and percentage difference. The time to draw the ROIs was also compared. RESULTS The percentage overlaps between the gold standard and the semiautomatic ROIs for total hip, femoral neck, and femoral shaft were 86.1%, 37.8%, and 96.1%, respectively, and the percentage differences were 14.5%, 89.7%, and 4.7%, respectively. In the same order, the percentage overlap between the gold standard and the manual ROIs were 85.2%, 39.1%, and 95.2%, respectively, and the percentage differences were 19.9%, 91.6%, and 12.2%, respectively. The semiautomatic method was approximately 9.5, 2.5, and 67 times faster than the manual method for segmenting total-hip, femoral-neck, and femoral-shaft ROIs, respectively. CONCLUSION We have developed and validated a semiautomatic procedure whereby ROIs at the hip are defined using the CT component of an (18)F-PET/CT scan. The percentage overlap and percentage difference results between the semiautomatic method and the manual method for ROI delineation were similar. Two advantages of the semiautomatic method are that it is significantly quicker and eliminates some of the variability associated with operator or reader input. The tube current used for the CT scan was associated with an effective dose 8 times lower than that associated with a typical diagnostic CT scan. These results suggest that it is possible to segment bone ROIs from low-dose CT for later transfer to PET in a single PET/CT procedure without the need for an additional high-resolution CT scan.
-
7.
Diagnostic imaging of higher brain dysfunction in patients with adult moyamoya disease using statistical imaging analysis for [123I]iomazenil single photon emission computed tomography.
Nakagawara, J, Osato, T, Kamiyama, K, Honjo, K, Sugio, H, Fumoto, K, Murahashi, T, Takada, H, Watanabe, T, Nakamura, H
Neurologia medico-chirurgica. 2012;(5):318-26
-
-
Free full text
-
Abstract
[123I]iomazenil (IMZ) is a specific radioligand for the central benzodiazepine (BZ) receptor that may be useful as a marker of cortical neuron loss after cerebral ischemia using single photon emission computed tomography (SPECT). This study used statistical imaging analysis for IMZ-SPECT to investigate the relationship between higher brain dysfunction and cortical neuron loss in the medial frontal lobes, to establish a confirmatory diagnosis of higher brain dysfunction in patients with adult moyamoya disease. IMZ-SPECT was estimated by three-dimensional stereotactic surface projections (3D-SSP). Cortical neuron loss was analyzed using the stereotactic extraction estimation (SEE) method (level 3: gyrus level) for 3D-SSP Z-score maps (Z-score >2). Extent of pixels with significant reduction of BZ receptor density within the target gyri (i.e. bilateral medial frontal gyri [MFGs] and anterior cingulate gyri [ACGs]) was calculated. In 6 patients with higher brain dysfunction, significant cortical neuron loss was observed in the bilateral MFGs in 4 patients, unilateral MFG in 1 patient, and bilateral ACGs in 2 patients. In 12 patients without higher brain dysfunction, no significant cortical neuron loss was observed in the bilateral MFGs or ACGs, and mild loss was observed in the bilateral MFGs in 2 patients, unilateral MFG in 4 patients, and unilateral ACG in 2 patients. Long-standing mild hemodynamic ischemia in the anterior circulation of patients with adult moyamoya disease could lead to incomplete brain infarction within the medial frontal lobes. Statistical imaging analysis using 3D-SSP and SEE methods for IMZ-SPECT could demonstrate significant cortical neuron loss in the bilateral frontal medial cortices involving MFG and/or ACG which correlate with higher brain dysfunction in patients with adult moyamoya disease.
-
8.
Computer-assisted microaneurysm turnover in the early stages of diabetic retinopathy.
Bernardes, R, Nunes, S, Pereira, I, Torrent, T, Rosa, A, Coelho, D, Cunha-Vaz, J
Ophthalmologica. Journal international d'ophtalmologie. International journal of ophthalmology. Zeitschrift fur Augenheilkunde. 2009;(5):284-91
Abstract
PURPOSE To assess the reliability of microaneurysm turnover, computed from color fundus photographs, in evaluating diabetic retinopathy in patients with type 2 diabetes and nonproliferative retinopathy. METHODS A new method (MA-Tracker) was developed to count microaneurysms by mapping their locations through image co-registration. To compute the reliability of microaneurysm turnover, 3 different graders were asked to earmark microaneurysms on the same set of color fundus photographs. RESULTS The total numbers of microaneurysms earmarked in each of 5 visits suggest that microaneurysms remain stable over time (p >or= 0.138). However, an analysis of each microaneurysm showed that only 29.4% remained at the same location. By computing the formation and disappearance rates of microaneurysms (2.3 and 1.7 microaneurysms/year, respectively), a significant turnover of microaneurysms was found. CONCLUSIONS The formation and disappearance rates of microaneurysms obtained from color fundus photographs using MA-Tracker show very good agreement between different graders, and can be used as indicators of microaneurysm turnover in the initial stages of diabetic retinopathy.
-
9.
In vivo monitoring of cutaneous edema using spectral imaging in the visible and near infrared.
Stamatas, GN, Southall, M, Kollias, N
The Journal of investigative dermatology. 2006;(8):1753-60
-
-
Free full text
-
Abstract
Tissue inflammation is often accompanied by local interstitial fluid accumulation expressed as edema. Edema can be the manifestation of infection, lymphatic blockage, wound healing, or even cancer, and is typically graded visually. Here we demonstrate that the edema reaction can be objectively quantitated in vivo by the use of spectral imaging. To this end we applied the method on a histamine-induced cutaneous edema model. Apparent concentrations of oxy-hemoglobin, deoxy-hemoglobin, and water were calculated for each pixel of a spectral image stack. These values were used to construct concentration maps for each of these molecules as well as an intensity map of an optical tissue-scattering parameter. The oxy-hemoglobin and the tissue water maps are two-dimensional quantitative representations of the skin areas involved in erythema and edema, respectively. These maps demonstrated characteristics of the wheal-and-flare reaction and their gray-level intensities were dependent on the applied histamine dose. We conclude that spectral imaging can be a valuable noninvasive tool in the study of edema pathology and can be used to monitor the edema reaction in vivo or follow the efficacy of treatments in a clinical setting.
-
10.
Screening using compressed digital retinal images successfully identifies retinopathy.
Leese, GP, Ellingford, A, Morris, AD, Ellis, JD, Cunningham, S
Diabetes care. 2003;(1):247