Focal orbital amyloidosis presenting as rectus muscle enlargement: CT and MR findings.

We report a case of focal orbital amyloidosis involving rectus muscles, which is an extremely rare clinical condition. CT scans showed rectus muscle enlargement with punctate calcifications. Heterogeneous hypointensity was present on T2-weighted MR images, and homogeneous enhancement was seen on fat-saturated contrast-enhanced images of the muscles. These imaging findings seem to be suggestive of amyloidosis. Focal amyloidosis should be included in the differential diagnosis of extraocular muscle enlargement.     

Reproducibility of a semi-automatic method for 6-point vertebral morphometry in a multi-centre trial

Purpose

To evaluate the reproducibility of a semi-automated system for vertebral morphometry (MorphoXpress) in a large multi-centre trial.

Materials and methods

The study involved 132 clinicians (no radiologist) with different levels of experience across 20 osteo-centres in Italy. All have received training in using MorphoXpress. An expert radiologist was also involved providing data used as standard of reference. The test image originate from normal clinical activity and represent a variety of normal, under and over exposed films, indicating both normal anatomy and vertebral deformities. The image was represented twice to the clinicians in a random order. Using the software, the clinicians initially marked the midpoints of the upper and lower vertebrae to include as many of the vertebrae (T5-L4) as practical within each given image. MorphoXpress performs the localisation of all morphometric points based on statistical model-based vision system. Intra-operator as well inter-operator measurement of agreement was calculated using the coefficient of variation and the mean and standard deviation of the difference of two measurements to check their agreement.

Results

The overall intra-operator mean differences in vertebral heights is 1.61 ± 4.27% (1 S.D.). The overall intra-operator coefficient of variation is 3.95%. The overall inter-operator mean differences in vertebral heights is 2.93 ± 5.38% (1 S.D.). The overall inter-operator coefficient of variation is 6.89%.

Conclusions

The technology tested here can facilitate reproducible quantitative morphometry suitable for large studies of vertebral deformities.     

Production of a range image for facial motion analysis: a method for analyzing lip motion.

To analyze the lip movement of patients with cleft lip and palate in detail, we developed a novel technique to produce a range image from a video-based motion capture system, and a unique technique to analyze lip movements in detail three-dimensionally. The accuracy of the range image obtained from the present system was investigated using a positioning actuator with a high accuracy and a known object, and by comparisons with the range images produced from a laser scanner with a cast model of a face. The lip motions of six healthy adults during phonation was analyzed.     

Motion correction for the quantification of mitral regurgitation using the control volume method.

Quantifying mitral regurgitation is difficult because of the complexity of the flow, geometry and motion of the mitral valve. In this paper a MRI compatible phantom was built incorporating a left ventricle and mitral valve motion. Valve motion was obtained using a pneumatic piston. The mitral valve was made regurgitant and the regurgitant volume quantified using a modified control volume method. The modification to the method was the addition of mitral motion correction. This was attained by moving the control volume in unison with the mitral valve and by correcting for this motion in the integration of velocity. This correction was found to be simple, in that it represented the volume swept out by the moving control surface. The measured regurgitant volume was compared to a second MR measurement using a single slice technique, made possible by the tubular construction of the phantom's left atrium. Regression analysis between these two methods produced a regression line of y = 0 + 1.02 x; R = 0.97; standard error of the estimate = 3.47 ml.     

Validation of the Yale circumferential quantification method using 201Tl and 99mTc: a phantom study.

The Yale circumferential quantification (Yale CQ) method for quantification of SPECT images has been validated previously using empirically derived correction factors. In the present studies, the Yale CQ method was further validated using 2 SPECT gamma cameras and 2 radioisotopes. METHODS: SPECT images were acquired from cardiac phantoms with multiple fillable inserts to simulate myocardial perfusion defects of varying extents and severities. Seventy phantom configurations were created. One hundred and forty SPECT images (70 with 99mTc and 70 with 201TI) were acquired using a triple-head SPECT camera. SPECT defects were quantified using the Yale CQ method, with incorporation of 99mTc- and 201TI-derived normal databases and correction factors. RESULTS: Quantified phantom SPECT defect sizes acquired with 99mTc correlated well with actual calculated defect sizes (r = 0.96, y = 0.92x - 0.41). Bland-Altman analysis of agreement revealed strong agreement over a wide range of defect sizes, with a mean error of 1.2% and 2 SDs of 5.0%. Overall 201TI SPECT defect sizes also correlated well with actual defect sizes (r = 0.92), but there was a systematic underestimation (y = 0.72x - 0.76). Bland-Altman analysis showed underestimation over the entire range of defect sizes, with a mean error of 3.4% and 2 SDs of 7.5%. Implementation of a normal 201TI phantom database improved accuracy of quantification (r = 0.95, y = 0.87x - 1.36). The addition of 201TI-specific correction factors further improved accuracy (r= 0.94, y = 0.98x - 1.52). Reproducibility of SPECT defect sizes quantification for 99mTc using 2 gamma cameras was excellent (r = 0.98, y = 0.98x + 0.84). CONCLUSION: The Yale CQ SPECT quantification method, using the empirically derived correction factors, provides accurate and reproducible quantification of phantom defects over a wide range of defect sizes. Accurate quantification of 201TI and 99mTc SPECT defect sizes requires radiotracer-specific normal databases.     

Left atrial dimension on the frontal thoracic radiograph: a method for assessing left atrial enlargement.

Left atrium size on the frontal radiograph was assessed by measuring the distance from the middle of the "double density" to the left main bronchus in 148 normal patients and 48 consecutive patients with echocardiographic evidence of left atrial enlargement. The measurement was less than 7.0 cm in 96% of normal patients and greater than 7.0 cm in 90% of patients with left atrial enlargement. This measurement is more easily obtainable than measurements and signs requiring a cardiac series, and is usually readily available for sequential evaluations of left atrial size. It is a less reliable gauge of left atrial size in children.     

SPECT quantification: a simplified method of attenuation and scatter correction for cardiac imaging.

The quantitative and visual interpretation of SPECT myocardial perfusion images is limited by physical factors such as photon attenuation, Compton scatter, and finite resolution effects. A method of attenuation correction is described for use in nonhomogeneous media and applied to cardiac SPECT imaging. This method, termed multiplicative variable attenuation compensation (MVAC), uses tissue contours determined from segmentation of a transmission scan to assign a priori determined attenuation coefficients to different tissue regions of the transaxial images. An attenuation correction map is then constructed using a technique inspired by Chang's method that includes regionally dependent attenuation within the chest cavity and is applied after reconstruction by filtered backprojection. Scatter correction using the subtraction of a simultaneously acquired scatter window image enables the use of narrow beam attenuation coefficients. Experimental measurements to evaluate these methods were conducted for 201Tl and 99mTc SPECT using a homomorphic cardiac phantom. Finite resolution effects were included in the evaluation of results by computer simulation of the three-dimensional activity distribution. The correction methodology was shown to substantially improve both relative and absolute quantification of uniform and nonuniform regions of activity in the phantom's myocardial wall.     

A new method for quantification of hepatobiliary scintigraphy using 99mTc-mebrofenin. A comparative study

A method based upon the application of mathematical techniques of deconvolution on the classical compartmental model for the quantitative study of liver function from hepatobiliary scintigraphy using 99mTc-mebrofenin data is proposed. The theory in which the method is based upon is presented and a comparison with a published methodology of obtaining the hepatic extraction after scintigraphic sudies has been performed using the results on 36 rats studies obtained with the two methods. A highly significant correlation between the two techniques was verified. The characteristics of the two methodologies, the proposed one based upon a theoretical approach and the other one on an empirical approximation are discussed. Comments are made on the interest and limitations of the presented technique that may be an useful tool for the evaluation of hepatic insufficiency.     

Indium-111 whole-body retention: a method for quantification of disease activity in inflammatory bowel disease.

Quantification of disease activity in inflammatory bowel disease (IBD) has been by measurement of fecal excretion of 111In-granulocytes. The difficulties of this method prompted us to evaluate quantification of whole-body 111In retention, expressed as a percentage of whole-body activity at 3 hr following injection, as an alternative method. The patient stood in front of the uncollimated gamma camera at a distance of 4 m and counts were collected over 2 min. The geometric mean was taken of posterior and anterior counts and compared with a 111In standard. The lower limit of the 95% confidence interval for whole-body retention in normals was 90%. Forty-five studies were performed on 33 patients with IBD. They were assessed in two groups, one to whom routine instructions for the collection of feces were given (Group A) but who did not always comply. The other group received oral and written instructions and were also monitored during the collection period (Group B) and reported full fecal collection. Although in Group A the correlation between fecal excretion and whole-body retention was good (r = 0.7, n = 32; p less than 0.001), in Group B the relationship between fecal excretion and whole-body retention was significantly better (r = 0.95, n = 18; p less than 0.001). On average, 111In whole-body retention was consistent with findings obtained during imaging: 111In excretion (100-whole-body retention) was 7.8% +/- 4.9% in 5 normal scans, 10% +/- 5.9% in 17 (+) scans, 22.3% +/- 8% in 20 (++) scans and 57% +/- 16% in 8 ( ) scans. We conclude that imaging is more sensitive than whole-body retention and fecal excretion in the detection of disease, but for quantification, whole-body retention is an accurate reliable alternative to fecal excretion.     

Scintigraphy in duodeno-gastric reflux: a new method of quantification

A prospective study is undertaken in order to demonstrate the ability of scintigraphy with a non compartmental analysis to quantitate the duodeno-gastric reflux. 24 patients have been examined, sitting in front of a gamma camera: 12 with an endoscopically proved reflux and 12 normal subjects or volunteers. About 15 min after an injection of 148 to 222 MBq 99Tcm-IDA they were given a meal labelled with 37 MBq 113Inm-DTPA. Images were recorded for 2 h. Equal size gastric and duodenal ROIs were selected over the duodenum and stomach, avoiding overlap with neighbouring organs. The reflux index based upon the occupancy principle is calculated from the gastric and duodenal curves. It is the ratio between the gastric and duodenal ROI IDA fluxes. The value of the reflux index is 3 +/- 1.8% in normal subjects and 45 +/- 33% in pathological cases. Our method, which does not require intubation, quantitatively evaluates biliary reflux independently of injected dose and hepatic or gallbladder function.     

Development of a simple non-invasive microsphere quantification method for cerebral blood flow using I-123-IMP

Objective

In clinical practice, measurement of the rCBF has mainly been conducted by I-123-N-isopropyl-p-iodoamphetamine (¹²³I-IMP) SPECT using the microsphere (MS) method, with continuous arterial blood sampling. While several non-invasive ¹²³I-IMP quantification methods have been developed, their accuracy has been shown to be lower than that of the MS method. Therefore, a non-invasive quantification method for use in routine clinical practice is being sought. The purpose of this study was to develop a simple non-invasive ¹²³I-IMP quantification method (SIMS method) with a simple input function-determining protocol based on the MS method.

Method

The input function for the SIMS method was determined using the administered dose and the integrated lung washout ratio obtained by analyzing the count–time activity curve of the pulmonary artery and lung on dynamic chest images. The mean CBF (mCBF) and input function measured in 80 patients by the SIMS method was compared with those determined using the MS method.

Result

A good correlation was observed between the counts measured by continuous arterial blood sampling in the MS method and the estimated counts by image analysis in the new method (r = 0.94, p < 0.01). Similarly, a good correlation was observed between the mCBF values determined by the MS method and the SIMS method (r = 0.83, p < 0.01).

Conclusion

The mCBF values determined by the SIMS method were closely consistent with the values obtained by the MS method. This finding indicates the possibility of use of the SIMS method for routine clinical study.

     

CT attenuation correction for myocardial perfusion quantification using a PET/CT hybrid scanner.

In routine PET, a 10- to 20-min transmission scan with a rotating (68)Ge source is commonly obtained for attenuation correction (AC). AC is time-consuming using this procedure and could considerably be shortened by instead using a rapid CT scan. Our aim was to evaluate the feasibility of CT AC in quantitative myocardial perfusion PET using a hybrid PET/CT scanner. METHODS: (13)N-labeled NH(3) and PET were used to measure myocardial blood flow (MBF) (mL/min/g) at rest and during standard adenosine stress. In group 1 (n = 7), CT scans (0.5 s) of the heart area with different tube currents (10, 40, 80, and 120 mA) were compared with a standard (68)Ge transmission (20 min) and with no AC. In group 2 (n = 3), the repeatability of 8 consecutive CT scans at a tube current of 10 mA was assessed. In group 3 (n = 4), emission was preceded and followed by 3 CT scans (10 mA) and 1 (68)Ge scan for each patient. For reconstruction, filtered backprojection (FBP) was compared with iterative reconstruction (IT). RESULTS: For group 1, no significant difference in mean MBF for resting and hyperemic scans was found when emission reconstructed with (68)Ge AC was compared with emission reconstructed with CT AC at any of the different tube currents. Only emission without any correction differed significantly from (68)Ge AC. For group 2, repeated measurements revealed a coefficient of variance ranging from 2% to 5% and from 2% to 6% at rest and at stress, respectively. For group 3, similar reproducibility coefficients (RC) for MBF were obtained when (68)Ge AC(FBP) was compared with (68)Ge AC(IT) (RC = 0.218) and when CT AC(FBP) was compared with CT AC(IT) (RC = 0.227). Even better reproducibility (lower RC) was found when (68)Ge AC(FBP) was compared with CT AC(FBP) (RC = 0.130) and when (68)Ge AC(IT) was compared with CT AC(IT) (RC = 0.146). CONCLUSION: Our study shows that for the assessment of qualitative and quantitative MBF with a hybrid PET/CT scanner, the use of CT AC (with a tube current of 10 mA) instead of (68)Ge AC provides accurate results.     

Unilateral breast enlargement: a rare complication of subclavian vein catheterization for hemodialysis.

Radiologic findings of an unusual uremic case of marked unilateral breast enlargement due to subclavian vein stenosis after subclavian catheterization for hemodialysis are presented.     

Improved method for quantification of regional cardiac function in mice using phase‐contrast MRI

Phase‐contrast magnetic resonance imaging is a technique that allows for characterization of regional cardiac function and for measuring transmural myocardial velocities in human hearts with high temporal and spatial resolution. The application of this technique (also known as tissue phase mapping) to murine hearts has been very limited so far. The aim of our study was to implement and to optimize tissue phase mapping for a comprehensive assessment of murine transmural wall motion. Baseline values for regional motion patterns in mouse hearts, based on the clinically used American Heart Association's 17‐segment model, were established, and a detailed motion analysis of mouse heart for the entire cardiac cycle (including epicardial and endocardial motion patterns) is provided. Black‐blood contrast was found to be essential to obtain reproducible velocity encoding. Tissue phase mapping of the mouse heart permits the detailed assessment of regional myocardial velocities. While a proof‐of‐principle application in a murine ischemia–reperfusion model was performed, future studies are warranted to assess its potential for the investigation of systolic and diastolic functions in genetically and surgically manipulated mouse models of human heart disease. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.     

PC VIPR: a high-speed 3D phase-contrast method for flow quantification and high-resolution angiography

BACKGROUND AND PURPOSE: Three-dimensional phase-contrast (3DPC) is limited by long imaging times, limited coverage, flow artifacts, and the need to perform multiple additional 2D examinations (2DPC) to measure flow. A highly undersampled 3D radial acquisition (isotropic-voxel radial projection imaging [PCVIPR]) makes it possible to increase the product of volume coverage and spatial resolution by a factor of 30 for the same imaging time as conventional Cartesian 3DPC. This provides anatomic information over a large volume with high isotropic resolution and permits retrospective measurement of average flow rates throughout the volume. METHODS: PCVIPR acquires a reference and three flow-encoded acquisitions for each VIPR projection. Complex difference images were formed by combining information from all flow directions. Following retrospective definition of planes perpendicular to selected vessels, volume flow rates were determined by using phase-difference information. The accuracy of average flow measurement was investigated in a phantom and in six volunteers. Anatomic PCVIPR images acquired in three patients and three volunteers by using a 384(3) matrix were compared with conventional Cartesian 3DPC. RESULTS: The flow validation produced R2 = 0.99 in vitro and R2 = 0.97 in vivo. PCVIPR produced minimal streak and pulsatile flow artifacts. PCVIPR produced far higher resolution and volume coverage in comparable imaging times. The highest acceleration factors relative to 3DPC were achieved by using gadolinium-contrast material. Ultimately, acceleration factors are limited by signal-to-noise ratio. CONCLUSION: PCVIPR rapidly provides isotropic high-resolution angiographic images and permits retrospective measurement of average flow rate throughout the volume without the need to prescribe multiple 2D acquisition planes.