Detection of age-related changes in thoracic structure and function by computed tomography, magnetic resonance imaging, and positron emission tomography

It is useful to understand the normal changes in structure and function in the thorax that occur with age. Thus, we present the following quantitative preliminary data obtained from retrospective quantitative analysis of computed tomography (CT) and positron emission tomography (PET) examinations in subjects 0 to 90 years of age: Mean lung standard uptake values were found to significantly increase with increasing age and with increasing body mass index (BMI). Mean lung attenuation was seen to statistically significantly decrease with increasing age in subjects who had a CT scan, had a nonsignificant tendency to decrease with increasing age in subjects with a PET/CT scan, had a nonsignificant tendency to increase with increasing BMI, and was seen to significantly increase with increasing mean lung standard uptake values. Mean lung volumes were not noted to significantly change with increasing age in adult subjects whether or not they were normalized to the craniocaudal thoracic lengths, although mean lung volumes significantly increased with increasing age in pediatric subjects. Mean lung volumes had a nonsignificant tendency to decrease with increasing BMI, although normalized mean lung volumes significantly decreased with increasing BMI. Lung metabolic volumetric products were not noted to significantly change with increasing BMI or with increasing age. In this work, we also review the literature regarding normal structural and functional changes in the thorax with age.     

Assessment of age-related changes in abdominal organ structure and function with computed tomography and positron emission tomography

With the size of the aged population in the United States expected to grow considerably during the next several decades, the number of imaging studies performed on such aged individuals will similarly increase. Thus, it is important to understand normal age-related changes in the structural and functional imaging appearance of the abdominal organs. We therefore present preliminary data and a review of the literature relevant to structural and functional changes in the abdominal organs of children and older adults. In a retrospective study of both adult and pediatric populations, we used computed tomography (CT), positron emission tomography (PET), and PET/CT imaging to investigate age-associated changes in size, attenuation, and metabolic function of the abdominal organs. Organs of interest include the liver, spleen, pancreas, kidneys, adrenal glands, stomach, small bowel, colon, and rectum. Although volumes of adult liver, spleen, pancreas, and kidneys do not change significantly with age, adult left and right adrenal gland volumes do significantly increase with age (r = 0.2823, P = 0.0334, and r = 0.3676, P = 0.0049, respectively). Also, the attenuation of adult liver (r = -0.2122, P = 0.0412), spleen (r = -0.4508, P < 0.0001), pancreas (r = -0.5124, P = 0.0007), and left and right adrenal gland (r = -0.5835, P < 0.0001 and r = -0.6135, P < 0.0001, respectively) decrease significantly with increasing age. Every organ studied in the pediatric population demonstrates a positive association between organ volume and age. Significant age-related changes in organ function are noted in the adult liver and small bowel, with the liver demonstrating a positive association between metabolic activity and age (r = 0.4434, P = 0.0029) and the small bowel showing an inverse association between mean small bowel standardize uptake value and age (r = -0.2435, P = 0.0174). Also, the maximum overall small bowel and colon metabolic activity in children increases with age (r = 0.6478, P = 0.0008). None of the other organs studied (ie, spleen, pancreas, adrenal glands, stomach, colon, rectum) demonstrate significant changes in metabolism with advancing age. The metabolic volumetric product (calculated as the product of organ volume and mean organ SUV) of the liver and spleen does not change significantly with age. In conclusion, various abdominal organs demonstrate differential changes in volume, attenuation, and/or metabolism with increasing age in pediatric and adult populations.     

Assessment of age-related morphological and functional changes of selected structures of the head and neck by computed tomography, magnetic resonance imaging, and positron emission tomography

The head and neck is a complex anatomical region that can be evaluated using many imaging modalities. It is important to discern normal structures from ones that are affected by disease and to study how these structures change in their morphological and functional properties with aging. Therefore, using magnetic resonance imaging (MRI), we retrospectively evaluated volumes of the parotid glands, submandibular glands, thyroid gland, tongue, soft palate, and lingual tonsils in 64 subjects ages 13 to 81 years. Volume, attenuation (HU), and metabolic activity (maximum SUV) of the parotid, submandibular, and thyroid glands were assessed retrospectively using positron emission tomography/computed tomography (PET/CT) imaging in 35 subjects ages 10 to 76 years. Metabolic activity (maximum SUV) of the parotid, submandibular, and sublingual glands; tongue; adenoids; and tonsils (lingual and palatine) were evaluated retrospectively using PET imaging in 15 subjects ages 6 to 20 years. Metabolic volumetric products of the parotid, submandibular, and thyroid gland were calculated and analyzed with increasing age in subjects who underwent PET/CT imaging. Structures that exhibited statistically significant changes (P < 0.05) with increasing age included the submandibular glands, thyroid gland, soft palate, and adenoids. The CT volume of the submandibular glands increased with age, and the attenuation decreased with age with statistical significance. The thyroid gland volume, as measured using MRI, showed a statistically significant decrease with aging. The volume of the soft palate and lingual tonsils, as measured by MRI, exhibited a statistically significant decrease in volume with aging. The maximum SUV of the adenoids demonstrated a statistically significant decrease with aging. In conclusion, CT, MRI, and PET may be used to quantitatively and qualitatively assess structures of the head and neck and are useful in the assessment of structural and functional changes of these structures with aging.     

Delineation of gliomas with magnetic resonance imaging using Gd-DTPA in comparison with computed tomography and positron emission tomography

Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using 11C-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I-II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the T1 weighted SE sequences was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the T1 weighted SE sequences. A greater increase in signal intensity in T1 weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.     

Age-related structural and functional changes in the breast: multimodality correlation with digital mammography, computed tomography, magnetic resonance imaging, and positron emission tomography

Preliminary results generated from digital mammography, computed tomography, magnetic resonance imaging, and (18)F-fluorodeoxyglucose positron emission tomography demonstrate concordant findings of decreasing glandular tissue and decreasing metabolic activity with increasing age. These results are presented in the context of a detailed literature review summarizing age-related changes in the breast, both from the histologic/physiologic and the imaging perspectives. We also discuss potential applications of this approach and emphasize the importance of new advanced imaging technologies to offer high levels of quantitative precision for tissue characterization for research and clinical purposes.     

Recurrent ovarian endodermal sinus tumor: demonstration by computed tomography,magnetic resonance imaging,and positron emission tomography

We report a case of recurrent endodermal sinus tumor.of the ovary that was identified and/or clearly depicted by computed tomography, magnetic resonance imaging, and positron emission tomography. The potential roles of various imaging modalities in the detection of recurrent endodermal sinus tumor are discussed.     

Imaging diabetes mellitus with coronary computed tomography angiography, cardiovascular magnetic resonance, and positron emission tomography

The prevalence and medical expense associated with diabetes mellitus continue to increase. Using the diagnostic imaging techniques of coronary computed tomography angiography, cardiovascular magnetic resonance, and positron emission tomography, it may be possible to make earlier, non-invasive diagnoses of the type and extent of disease, thereby preventing or delaying some morbidity and mortality.     

超声、CT、MRI及PET对于肿瘤血管生成的标准化测量的建议

摘要本文讨论了US、CT、MRI和PET4种方法评估肿瘤血管生成的标准。在肿瘤研究及临床应用中,这些方法对于评价治疗后血管的反应尤其重要。成像方法已从过去主观解释图像的形式转变为如今完全成熟的客观的科学方法,放射学专家在评价病变时都应该严格选择最佳的技术方法。严格采用合适的成像方案并保证影像质量,实验才会由制药公司及其他资金赞助方资助。     

Standardising measurement of tumour vascularity by imaging: recommendations for ultrasound, computed tomography, magnetic resonance imaging and positron emission tomography

This review analyses the need for, and likely impact of, four subsequent papers which discuss the importance of standardisation of ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) when assessing tumour vascularity. This is particularly important when measuring the vascular effects of therapeutic agents in oncological research and practice. As imaging inexorably moves from the subjective interpretative art-form of the past into its modern role as a fully fledged objective scientific discipline, it is incumbent on all radiologists to understand the need for strict adherence to perceived best practice when evaluating lesions as part of trials. Indeed trials may only be funded by pharmaceutical companies and other grant-giving bodies if rigorous adherence to imaging protocols and quality assurance is in place. Key Points ? Various imaging methods can now robustly assess tumour vascular support. ? US, CT, MRI and PET are increasingly used to assess tumour vascularity. ? These techniques have reached technical maturity for use in therapeutic oncological trials. ? Consensus guidelines about using these techniques in assessing tumour vascularity are introduced. ? Image acquisition protocols and quality assurance must be established for large trials.     

Positron emission tomography/computed tomography fusion imaging in brown adipose tissue

Fluorine-18 fluoro deoxyglucose positron emission tomography (F-18 FDG PET) imaging is an exciting modality for the study of pathophysiology. The fusion of computed tomography (CT) anatomic data to metabolic F-18 FDG PET data allows accurate mapping of the metabolic activity of the body. With each patient evaluated with fusion PET/CT imaging, valuable information is obtained regarding anatomic and physiological abnormalities and normal variants. We describe 4 cases in which the unusual distribution of increased FDG metabolism localized to fat, which we propose represents brown adipose tissue. The accurate anatomic localization of this hypermetabolic fat is aided by imaging these patients on a combined PET/CT system.     

Diagnostic performance of fluorodeoxyglucose positron emission tomography/magnetic resonance imaging fusion images of gynecological malignant tumors: comparison with positron emission tomography/computed tomography

Purpose

We compared the diagnostic accuracy of fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and PET/magnetic resonance imaging (MRI) fusion images for gynecological malignancies.

Materials and methods

A total of 31 patients with gynecological malignancies were enrolled. FDG-PET images were fused to CT, T1- and T2-weighted images (T1WI, T2WI). PET-MRI fusion was performed semiautomatically. We performed three types of evaluation to demonstrate the usefulness of PET/MRI fusion images in comparison with that of inline PET/CT as follows: depiction of the uterus and the ovarian lesions on CT or MRI mapping images (first evaluation); additional information for lesion localization with PET and mapping images (second evaluation); and the image quality of fusion on interpretation (third evaluation).

Results

For the first evaluation, the score for T2WI (4.68 ± 0.65) was significantly higher than that for CT (3.54 ± 1.02) or T1WI (3.71 ± 0.97) (P < 0.01). For the second evaluation, the scores for the localization of FDG accumulation showing that T2WI (2.74 ± 0.57) provided significantly more additional information for the identification of anatomical sites of FDG accumulation than did CT (2.06 ± 0.68) or T1WI (2.23 ± 0.61) (P < 0.01). For the third evaluation, the three-point rating scale for the patient group as a whole demonstrated that PET/T2WI (2.72 ± 0.54) localized the lesion significantly more convincingly than PET/CT (2.23 ± 0.50) or PET/T1WI (2.29 ± 0.53) (P < 0.01).

Conclusion

PET/T2WI fusion images are superior for the detection and localization of gynecological malignancies.     

PET和SPECT结合延迟增强MRI评价存活心肌的进展

冠状动脉硬化性心脏病可造成不同程度的心肌损害,而只有存活心肌经血运重建后心功能得到改善,患者才能从中获益。因此,选择一种有效、准确的评价存活心肌的方法对选择治疗方案,决定是否进行血运重建治疗具有重要的临床指导意义。PET和SPECT是评价心肌存活的常用方法,近年来,随着MRI技术的迅速发展,临床应用也不断扩展,特别是心肌灌注延迟增强扫描显像的应用可从坏死组织中区分周围的存活心肌。     

Ameloblastic carcinoma of the mandible with metastasis to the skull and lung: advanced imaging appearance including computed tomography,magnetic resonance imaging and positron emission tomography computed tomography

Ameloblastic carcinoma is a very rare malignant odontogenic tumour with characteristic histopathological and clinical features, which requires aggressive surgical treatment and surveillance and, therefore, differs from ameloblastoma. Metastasis typically occurs in the lung. Only one patient with metastasis to the skull has previously been described and no prior case reports have presented MRI and positron emission tomography-CT (PET-CT) imaging findings. We describe a case of ameloblastic carcinoma with metastasis to the skull and lung with emphasis on imaging features including MRI and PET-CT.     

Radiology imaging of renal structure and function by computed tomography, magnetic resonance imaging, and ultrasound

Radiological techniques are now able to provide morphologic, functional, and structural information relative to kidney diseases. Many of these approaches have been proposed experimentally, but validation studies in patients still remain mandatory. Contrast-enhanced ultrasound allows for the measurement of perfusion parameters. Multidetector computed tomography and magnetic resonance imaging make it possible to measure the differential function of filtration. Measurement of absolute glomerular filtration rate is still under development. Finally, magnetic resonance imaging is also able to provide information on the level of intrarenal oxygenation by the use of blood oxygenation level-dependent sequences and on cell density and water exchanges by the use of diffusion-sensitive acquisitions.     

Simultaneous whole body 18F-fluorodeoxyglucose positron emission tomography magnetic resonance imaging for evaluation of pediatric cancer: Preliminary experience and comparison with 18F-fluorodeoxyglucose positron emission tomography computed tomography

AIM: To describe our preliminary experience with simultaneous whole body ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography and magnetic resonance imaging (PET-MRI) in the evaluation of pediatric oncology patients.METHODS: This prospective, observational, single-center study was Health Insurance Portability and Accountability Act-compliant, and institutional review board approved. To be eligible, a patient was required to: (1) have a known or suspected cancer diagnosis; (2) be under the care of a pediatric hematologist/oncologist; and (3) be scheduled for clinically indicated ¹⁸F-FDG positron emission tomography-computed tomography (PET-CT) examination at our institution. Patients underwent PET-CT followed by PET-MRI on the same day. PET-CT examinations were performed using standard department protocols. PET-MRI studies were acquired with an integrated 3 Tesla PET-MRI scanner using whole body T1 Dixon, T2 HASTE, EPI diffusion-weighted imaging (DWI) and STIR sequences. No additional radiotracer was given for the PET-MRI examination. Both PET-CT and PET-MRI examinations were reviewed by consensus by two study personnel. Test performance characteristics of PET-MRI, for the detection of malignant lesions, including FDG maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADCmin), were calculated on a per lesion basis using PET-CT as a reference standard.RESULTS: A total of 10 whole body PET-MRI exams were performed in 7 pediatric oncology patients. The mean patient age was 16.1 years (range 12-19 years) including 6 males and 1 female. A total of 20 malignant and 21 benign lesions were identified on PET-CT. PET-MRI SUVmax had excellent correlation with PET-CT SUVmax for both benign and malignant lesions (R = 0.93). PET-MRI SUVmax > 2.5 had 100% accuracy for discriminating benign from malignant lesions using PET-CT reference. Whole body DWI was also evaluated: the mean ADCmin of malignant lesions (780.2 + 326.6) was significantly lower than that of benign lesions (1246.2 + 417.3; P = 0.0003; Student’s t test). A range of ADCmin thresholds for malignancy were evaluated, from 0.5-1.5 × 10^-3 mm²/s. The 1.0 × 10^-3 ADCmin threshold performed best compared with PET-CT reference (68.3% accuracy). However, the accuracy of PET-MRI SUVmax was significantly better than ADCmin for detecting malignant lesions compared with PET-CT reference (P < 0.0001; two-tailed McNemar’s test).CONCLUSION: These results suggest a clinical role for simultaneous whole body PET-MRI in evaluating pediatric cancer patients.     

Malignant pleural mesothelioma with heterologous osteoblastic elements: computed tomography, magnetic resonance, and positron emission tomography imaging characteristics of a rare tumor

The imaging findings of a rare mixed type of malignant mesothelioma of the pleura with heterologous bone stroma in a patient without a previous history of asbestos exposure are reported. Imaging findings of this type of bone-forming pleural mesothelioma are scarcely reported in the literature, with only a few case reports describing findings on conventional radiography, computed tomography, and magnetic resonance imaging. To the best of our knowledge, no positron emission tomography imaging characteristics of this type of mesothelioma have been previously reported.     

Myocardial imaging with 18F-fluoro-2-deoxyglucose positron emission tomography and magnetic resonance imaging in sarcoidosis

Purpose Despite accumulating reports on the clinical value of ¹⁸F-fluoro-2-deoxyglucose positron emission tomography (¹⁸F-FDG PET) and magnetic resonance imaging (MRI) in the assessment of cardiac sarcoidosis, no studies have systematically compared the images of these modalities. Methods Twenty-one consecutive patients with suspected cardiac sarcoidosis underwent cardiac examinations that included ¹⁸F-FDG PET and MRI. The association of ¹⁸F-FDG PET and MRI findings with blood sampling data such as serum angiotensin converting enzyme levels was also evaluated. Results Eight of 21 patients were diagnosed as having cardiac sarcoidosis according to the Japanese Ministry of Health and Welfare Guidelines for Diagnosing Cardiac Sarcoidosis. Sensitivity and specificity for diagnosing cardiac sarcoidosis were 87.5 and 38.5%, respectively, for ¹⁸F-FDG PET, and 75 and 76.9%, respectively, for MRI. When the ¹⁸F-FDG PET and MRI images were compared, 16 of 21 patients showed positive findings in one (n = 8) or both (n = 8) of the two modalities. In eight patients with positive findings on both images, the distribution of the findings differed among all eight cases. The presence of positive findings on ¹⁸F-FDG PET was associated with elevated serum angiotensin-converting enzyme levels; this association was not demonstrated on MRI. Conclusions Both ¹⁸F-FDG PET and MRI provided high sensitivity for diagnosing cardiac sarcoidosis in patients with suspected cardiac involvement, but the specificity of ¹⁸F-FDG PET was not as high as previously reported. The different distributions of the findings in the two modalities suggest the potential of ¹⁸F-FDG PET and MRI in detecting different pathological processes in the heart.