A Norwegian nationwide quality assurance project in nuclear medicine: total performance in bone scintigraphy measured with a new transmission phantom

A prototype version of a recently developed transmission phantom for simulation of radionuclide bone studies was used in a Norwegian nationwide quality assurance project. The design of the phantom made it possible to perform a receiver operation characteristic (ROC) examination with respect to the detection of radionuclide accumulation in the ribs. The participants were also asked to report accumulation in the spinal column. Images obtained by means of a uniform source and a four-quadrant bar pattern were used to judge resolution and homogeneity with the collimator used in the bone studies. The overall performance of the laboratories was satisfactory, but considerable variations were found. There was a marked correlation between the physician's performance and the resolution and homogeneity of the camera. Reports from stationary imaging were generally better than those that were based on whole-body scans.     

A multipurpose phantom for quality assurance of contrast-enhanced MR imaging of the breast

A phantom consisting of four components was developed to simulate contrast-enhanced MR imaging of the breast. These components included the correlation between the signal intensity and the contrast medium concentration, the uniformity of signals within surface coils, artefacts due to opposed-phase imaging effects, spatial resolution and the acquisition of relevant signal-to-time curves. Repetitive measurements demonstrated an excellent reproduction of phantom imaging with a deviation in signal intensity of approximately 5 %. The presented phantom allows the optimization of examination protocols as well as the comparison of different examination techniques. Furthermore, it enables the routine quality monitoring of contrast-enhanced MR imaging of the breast. Received: 28 May 1998; Revised: 3 September 1998; Accepted: 14 October 1998     

一种基于原型体模的宝石能谱CT成像的质量保证检测方法

目的：探讨宝石能谱 CT 成像(GSI)的质量保证检测方法。方法以纯净水和碘帕醇300对比剂为原料,配制9种不同浓度溶液,形成原型体模,在 GE Discovery CT750 HD 扫描仪上,采用常用头部 GSI 方案进行扫描,并在 GE AW4.6图像后处理工作站上进行图像后处理。结果基于等效原子序数直方图、基质散点分布图和 CT 值随射线能量变化的能谱曲线图,GSI 能够区分不同浓度碘溶液,并能定量分析其水和碘的含量。结论通过碘溶液原型体模检测 GSI 的定量分析能力是可行的。     

Image quality of mammography in Croatian nationwide screening program: comparison between various types of facilities

Purpose

The study was aimed to provide objective evidence about the mammographic image quality in Croatia, to compare it between different types of MG facilities and to identify the most common deficiencies and possible reasons as well as the steps needed to improve image quality.

Materials and methods

A total of 420 mammographic examinations collected from 84 mammographic units participating in the Croatian nationwide breast cancer screening program were reviewed in terms of four image quality categories: identification of patient and examination, breast positioning and compression, exposure and contrast, and artifacts. Those were rated using image evaluating system based on American College of Radiology and European Commission proposals. The results were compared among different types of mammographic units, and common image quality deficiencies were identified.

Results

Total image quality scores of 12.8, 16.1, 13.0 and 13.7 were found for general hospitals, university hospitals, private clinics and public healthcare centres, respectively. Average score for all mammographic units was 13.5 (out of 25 points). University hospitals were significantly better than all other mammography units in overall image quality, which was mostly contributed by better breast positioning practices. Private clinics showed the worst results in identification, exposure, contrast and artifacts.

Conclusions

Serious deficiencies in identification and breast positioning, which might compromise breast cancer screening outcome, were detected in our material. They occur mainly due to subjective reasons and could be corrected through additional staff training and improvement of working discipline.     

The value of bone scintigraphy,bone marrow scintigraphy and fast spin-echo magnetic resonance imaging in staging of patients with malignant solid tumours: a prospective study

The purpose of this prospective study was to define the value of bone scintigraphy (BS), bone marrow scintigraphy (BMS) and the new fast spin-echo (FSE) magnetic resonance imaging (MRI) sequences in screening for bone metastases in patients with solid malignant tumours. It was our particular interest to classify patients into a group with and a group without bone metastases, and not only to compare the absolute number of metastases detected by each method. Thirty-two patients were examined using technetium-99m dicarboxy propane diphosphonate bone scintigraphy, ^99mTc-labelled monoclonal anti-granulocyte antibodies for bone marrow scintigraphy and 1.5 T MRI using T1-weighted and FSE T2-weighted sequences. Against a reference standard obtained by re-evaluation of all clinical and imaging data 1 year after prospective BS, BMS and MRI had been performed, the three imaging modalities were falsely positive in two, eight and two cases and falsely negative in zero and four cases, respectively. BMS was falsely positive in eight patients because of vertebral marrow degeneration which caused photopenic defects which could not be differentiated from metastases. MRI showed these lesions to unequivocally contain fat. BMS and MRI were falsely negative in four cases because of the limited field of examination. In our study the key factor in classifying a patient as bone MI or MO was the possibility of surveying the entire skeleton, as is the case in BS, and not that MRI had a higher sensitivity compared to BS when analysis was on a lesion-by-lesion basis. BMS had the same limitations as MRI because the usual bone marrow distribution resulted in a physiologically limited field of view. We conclude that BS remains the method of choice in staging patients with solid tumours despite the fact that MRI is no longer a time-consuming method using FSE sequences. MRI has a complemantary role if special questions remain. BMS appears to have little value in the detection of bone metastases because of its poor specificity, its limited spatial resolution and its restriction to those areas of the skeleton containing haematopoietic marrow. Correspondence to: G.K. v. Schulthess     

Good reasons to implement quality assurance in nationwide breast cancer screening programs in Croatia and Serbia: Results from a pilot study

The purpose of this study is to investigate the need for and the possible achievements of a comprehensive QA programme and to look at effects of simple corrective actions on image quality in Croatia and in Serbia. The paper focuses on activities related to the technical and radiological aspects of QA. The methodology consisted of two phases. The aim of the first phase was the initial assessment of mammography practice in terms of image quality, patient dose and equipment performance in selected number of mammography units in Croatia and Serbia. Subsequently, corrective actions were suggested and implemented. Then the same parameters were re-assessed. Most of the suggested corrective actions were simple, low-cost and possible to implement immediately, as these were related to working habits in mammography units, such as film processing and darkroom conditions. It has been demonstrated how simple quantitative assessment of image quality can be used for optimisation purposes. Analysis of image quality parameters as OD, gradient and contrast demonstrated general similarities between mammography practices in Croatia and Serbia. The applied methodology should be expanded to larger number of hospitals and applied on a regular basis.     

PET/CT: a new imaging technology in nuclear medicine

This review discusses the technical background of combined PET and CT and considers the clinical applications of PET/CT imaging. Questions addressed include: Is PET/CT superior to PET imaging alone? If so, in which patient populations and in what respect? Can PET/CT imaging affect patient management? Can PET/CT be practiced economically? While much work remains to be done, the available data clearly suggest that PET/CT decreases imaging time per patient and, even for the experienced reader, significantly reduces the number of equivocal PET interpretations. PET/CT also has the ability to improve accuracy of PET image interpretation and to affect clinical decision making, thereby improving patient management. The nuclear medicine community should approach this new technology with an open mind and focus on its clinical usefulness. The decision regarding whether PET/CT should be part of the equipment in a given nuclear medicine or radiology practice largely depends on the specific patient population. It is concluded that present skepticism concerning combined PET/CT will subside once critics of this new modality have had the opportunity to clearly see on images its many advantages compared with either PET alone or conventional image fusion approaches.     

Reduction in dose from CT examinations of liver lesions with a new postprocessing filter: a ROC phantom study

Background: It is desirable to lower the dose from computed tomography (CT) examinations as much as possible without reducing diagnostic performance. Mathematical postprocessing filters are one tool to achieve dose reduction.

Purpose: To evaluate the possibilities of reducing CT doses from liver examinations using a new postprocessing filter.

Material and Methods: An anthropomorphic upper-abdomen phantom was used in receiver operating characteristic (ROC) studies of the detectability of liver lesions. A standard abdominal CT protocol was used. Only mA settings were changed; all other scan parameters were constant. The postprocessing filter used was SharpView CT, which provides context-controlled restoration of digital images using adaptive filters. Six readers were given a set of 10 images obtained at five different dose levels, each image with 32 predefined areas to be evaluated on a five-point scale. In total, 1920 areas were evaluated. At each dose level, the readers evaluated five images without enhancement and five images based on postprocessing filters. All images were randomized with respect to dose level.

Results: The postprocessing filter improved the diagnostic performance significantly compared to the unenhanced images at all dose levels. Radiation dose for abdominal CT examinations of liver lesions in the range 2-7 mm was reduced by 30% using postprocessing filters, while diagnostic performance of the examination was maintained or even improved.

Conclusion: This study indicates great potential for lowering doses for CT examinations of liver lesions using the new postprocessing filter. The software must be fully tested clinically to reliably assess the benefits of this filtration.     

~(11)C-CHO PET/CT显像与全身骨显像在前列腺癌复发患者骨转移中诊断价值

目的探讨~(11)C-CHO PET/CT显像与全身骨显像在前列腺癌复发患者骨转移中的诊断价值。方法回顾性分析自2011年5月至2015年5月沈阳军区总医院核医学科收治的前列腺癌复发患者96例(PSA:2.5-56.0 mg/L)。所有患者均在2周内行~(11)C-CHO PET/CT显像与全身骨显像,以活检、18F-FDG PET/CT、增强CT、MRI、临床随访等综合评价为诊断标准,比较两者诊断的灵敏度、特异度。结果 96例患者中,~(11)C-CHO PET/CT显像与全身骨显像,共发现57个阳性病灶,其中,46个病灶经后续确诊为转移瘤。~(11)C-CHO PET/CT显像与全身骨显像诊断转移灶灵敏度分别为93.3%、69.6%,特异度分别为90.9%、36.4%。~(11)C-CHO PET/CT显像发现骨外转移26处:局部复发10处、膈下淋巴结4处、膈上淋巴结2处、局部复发合并膈下淋巴结5处、膈上合并膈下淋巴结4处以及膈上淋巴结合并肺转移1处。结论在诊断前列腺癌复发患者骨转移方面,~(11)C-CHO PET/CT显像的诊断灵敏度和特异度优于传统全身骨显像,并且~(11)C-CHO PET/CT显像能够发现局部复发、淋巴结和远处器官转移病灶,获得更加准确的临床分期,有助于选择合适的治疗方案。     

Magnetic resonance relaxation times of normal tissue in the course of chemotherapy: a study in patients with bone sarcoma

To study the effect of chemotherapy on normal fat, skeletal muscle, and bone marrow, T1 and T2 relaxation times were measured in 15 patients with bone sarcoma before and after each cycle of preoperative chemotherapy. A section plane containing the tumor and if possible the nonaffected extremity was imaged with combined multiecho spin echo and inversion recovery pulse sequences. T1 and T2 relaxation times were calculated in the normal-appearing tissues. Although some variation was found in the values in the individual patient and between patients, no systematic changes of relaxation times of fat, muscle, or bone marrow occurred in the course of treatment. We conclude that the chemotherapy used in bone sarcoma has no effect on relaxation times of normal fat, muscle, and bone marrow, and that therefore these tissues may serve as a reference for the signal intensity of tumor.     

The performance of MRI in detecting subarticular bone erosion of sacroiliac joint in patients with spondyloarthropathy: A comparison with X-ray and CT

Objective

To assess the sensitivity and specificity of detecting subarticular bone erosion of sacroiliac (SI) joint in patients with spondyloarthritis (SpA) using MRI three-dimensional water selective balanced steady-state free precession sequence (3D-WS-bSSFP) and T1-weighted (T1W) sequence.

Materials and methods

Radiography, CT and MRI of SI joint from 43 SpA patients were retrospectively analyzed. MRI examination sequences include T1W, short tau inversion recovery (STIR) and 3D-WS-bSSFP. Two radiologists, blinded to clinical data, independently determined bone erosion at bilateral sacral and iliac sides of the SI joint on radiography, CT, T1W and 3D-WS-bSSFP respectively. X² test was used to compare the sensitivity of detecting bone erosion among different diagnostic methods.

Results

Of the 86 sacral and 86 iliac articular surfaces from the 43 cases, radiography, CT, MRI T1W and 3D-WS-bSSFP showed the presence of bone erosion in 40, 74, 50 and 71 articular surfaces respectively. CT and MRI 3D-WS-bSSFP demonstrated similar sensitivity (x² = 0.11, P = 0.74), and both were superior to radiography (x² = 15.17, P < 0.01 and x² = 12.78, P < 0.01, respectively) and T1W (x² = 7.26, P < 0.01 and x² = 5.62, P < 0.05). Using CT diagnosis as the gold standard, the sensitivity and specificity of detecting bone erosion for MRI 3D-WS-bSSFP and T1W sequences were 91.8%, 96.9%, and 60.8%, 94.9% respectively.

Conclusion

MRI 3D-WS-bSSFP sequence is associated with short scanning time, zero ionizing radiation, high sensitivity and specificity of displaying the subarticular bone erosion of SI joints in patients with SpA. Therefore, it can be considered an alternative to CT.     

Dual-energy CT virtual non-calcium technique for detection of bone marrow edema in patients with vertebral fractures: A prospective feasibility study on a single- source volume CT scanner

ObjectivesDual-energy computed tomography (DECT) is a recent development for detecting bone marrow edema (BME) in patients with vertebral compression fractures. The aim of this pilot study was to determine the reliability of single-source DECT in detecting vertebral BME using magnetic resonance imaging (MRI) as standard of reference.Materials and methodsNine patients with radiographic thoracic or lumbar vertebral compression fractures underwent both, DECT on a 320-row single-source scanner and 1.5 T MRI. Virtual non-calcium (VNC) images were reconstructed from the DECT volume datasets. Three blinded readers independently scored images for the presence of BME. Only vertebrae with loss of height in radiography (target vertebrae) were included in the analysis. A vertebra was counted as positive if two readers agreed on the presence of BME. Cohen’s kappa was calculated for interrater comparison. Intervertebral ratios of target and the reference vertebra were compared for CT attenuation and MR signal intensity in a reference vertebra using Spearman correlation. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.ResultsFourteen target vertebrae with a radiographic height loss were identified; eight of them showed BME on MRI, while DECT identified BME in 7 instances. There were no false positive virtual non-calcium images, resulting in a sensitivity of 0.88 (0.75–1.0 among all readers) and specificity of 1.0 (0.81–1.0). Interrater agreement was inferior for DECT (κ = 0.63–0.89) compared to MRI (κ = 0.9–1.0). Intervertebral ratio in VNC images strongly correlated with short-tau inversion recovery (r = 0.87) and inversely with T1 (-0.89). SNR (0.2 +/− 0.2 in VNC and 16.7 +/− 7.3 in STIR) and CNR (0.2 +/− 0.3 and 7.1 +/− 6.3) values were inferior in VNC.ConclusionsDetecting BME with single-source DECT is feasible and allows detection of vertebral compression fractures with reasonably high sensitivity and specificity. However, image quality of VNC reconstructions has to be improved to achieve better interrater agreement. Nonetheless, DECT might accelerate the diagnostic work-flow in patients with vertebral compression fractures in the future and reduce the number of additional MRI examinations.     

Evaluation of radiolucency condition in total hip arthroplasty: a statistical comparison of the diagnostic capability of digitised image vs conventional X-ray film

This work analyses the diagnostic capability of radiographic images taken from patients with total hip arthroplasty and visualised on monitor. Images were obtained with digital acquisition of conventional X-ray films. The investigated pathology is the absence of direct contact between bone and prosthesis (radiolucency). Three senior orthopaedists defined the diagnostic “truth” on well-defined regions of interest on 22 conventional X-ray films of total hip arthroplasty, obtaining a total of 110 reference ratings. Films were digitised by use of an X-ray scanner. Four readers evaluated the X-ray images, applying conventional and monitor visualisation. To show any difference between ratings on film and ratings on monitor a sensitivity, specificity and accuracy study jointly with a receiver operating characteristics (ROC) study were performed for each reader and for all combined readings. The intra-observer reproducibility of the radiographic protocol was equal to 87 % and the inter-observer one was in the range 85–92 %. The sensitivity, specificity and accuracy study together with the ROC analysis did not show significant differences between the two evaluation modes. The evaluation of radiolucency from digitised X-ray films visualised on a monitor resulted statistically comparable with the conventional evaluation on X-ray films. Received: 31 December 1998; Revised: 6 April 1999; Accepted: 30 June 1999     

Vertebral blood perfusion reduction associated with vertebral bone mineral density reduction: A dynamic contrast‐enhanced MRI study in a rat orchiectomy model

Purpose

To investigate the relationship between vertebral blood perfusion and vertebral bone mineral density (BMD) in a rat orchiectomy (ORX) model.

Materials and Methods

Nine 6‐month‐old male Wistar‐Kyoto rats were used. Computed tomography (CT) bone densitometry and dynamic MRI were performed at baseline and four weeks post‐ORX. MRI was performed on a 1.5T clinical MR scanner with a small surface coil placed under the rat lumbar spine region. A sagittal midsection of the lumbar spine was prescribed. Dynamic MRI was performed after a bolus injection of gadolinium‐tetraazacyclododecane tetraacetic acid (Gd‐DOTA) (0.3 mmol/kg) administered through a tail vein cannula. At a temporal resolution of 0.6 seconds, 800 images were acquired. Regions‐of‐interest were drawn comprising the medullary component of lumbar vertebrae L3–L6. Maximum enhancement was analyzed.

Results

Satisfactory CT and MRI data for analysis was obtained in all animals. Vertebral BMD decreased by 16.6% at four weeks post‐ORX (1.134 ± 0.035 vs. 0.946 ± 0.027 g/cm³, P = 0.008). MRI maximum enhancement decreased by 17% at four weeks post‐ORX (151.5 ± 12.0% vs. 125.8 ± 9.9%, P = 0.015).

Conclusion

Vertebral blood perfusion reduction is associated with vertebral BMD reduction in a male rat osteoporosis model. Perfusion MRI provides a new investigative technique for osteoporosis experimental research. J. Magn. Reson. Imaging 2008;28:1515–1518. © 2008 Wiley‐Liss, Inc.