Clinical and Translational Imaging最新文献

Abstract

Abstract

Abstract

Purpose

The aim of this retrospective study was to compare the MRI features between typical and atypical pheochromocytomas (Pheos) to specifically illustrate MRI features of atypical tumors for helping tumor diagnosis.

Methods

A total of 22 patients (14 women and 8 men, median age: 53 years, age range: 25–82 years) with Pheos evaluated using a 3 T MRI scanner were retrospectively collected; in particular, all patients had one tumor lesion, except in two cases who had two and three lesions, respectively, for a total of 25 tumor lesions.

Results

Of the total 25 tumor lesions included in our series, 12 lesions were classified as typical for their classical appearance on MRI (T1 hypointensity, T2 hyperintensity, no signal drop on T1 out-of-phase, restricted diffusion and persistent contrast enhancement). Conversely, the other 13 tumors were classified as having atypical lesions because they did not show the MRI features observed in typical Pheos; in particular, 3 lesions showed signal intensity suggestive of tumor hemorrhagic changes, 2 lesions were totally cystic with an internal fluid–fluid level and a thin capsula, 3 lesions showed predominantly cystic signal intensity with residual solid tissue in the peripheral capsula, and the remaining 5 lesions appeared as rounded partially cystic lesions with associated areas of solid tissue.

Conclusion

The imaging characterization of typical Pheos may be performed using MRI with specific imaging features; however, atypical Pheos represents a diagnostic challenge using MRI; in these tumors, cystic, necrotic, hemorrhagic, or fat changes may occur; thus, diagnostic pitfalls should be taken into consideration for MRI interpretation of such tumor type in clinical practice.

Abstract

FAPI PET/CT, an innovative medical imaging technique, has emerged as a promising method to target fibroblast activation protein (FAP). This novel approach offers numerous benefits, such as increased tumor absorption and reduced background noise. As a result, FAPI PET/CT images demonstrate a favorable ratio of tumor signal to background, allowing for precise tumor staging, characterization, and detection. Given the heightened expression of FAP in colorectal cancer (CRC), FAPI PET/CT has the potential to revolutionize CRC staging, restaging, and monitoring, as well as enhance treatment management and improve patient prognosis. This comprehensive review aims to provide a detailed overview of the current applications of FAPI PET/CT in CRC, while also proposing future research directions, specifically in comparison to the standard FDG PET imaging modality.

Purpose

Hypoxia is a major cause of radioresistance in head and neck cancer (HNC), resulting in treatment failure and disease recurrence. ¹⁸F-fluoromisonidazole ([¹⁸F]FMISO) PET has been proposed as a means of localising intratumoural hypoxia in HNC so that radiotherapy can be specifically escalated in hypoxic regions. This concept may be challenging to implement in routine clinical practice however, given that [¹⁸F]FMISO PET is costly, time consuming and difficult to access. The aim of this review was to summarise clinical studies involving [¹⁸F]FMISO PET and to appraise the evidence for its role in guiding radiotherapy treatment in HNC.

Methods

A comprehensive literature search was conducted on PubMed and Web of Science databases. Studies investigating [¹⁸F]FMISO PET in newly diagnosed HNC patients were considered eligible for review.

Results

We found the following important results from our literature review: (1) Studies have demonstrated a correlation between [¹⁸F]FMISO PET and other hypoxia biomarkers, although the results are not consistent enough to propose a proxy biomarker of [¹⁸F]FMISO PET. (2) [¹⁸F]FMISO PET uptake changes during a course of radiotherapy treatment, suggesting that imaging should be repeated during treatment. (3) Tumour recurrences do not always occur within the pretreatment hypoxic volume on [¹⁸F]FMISO PET. (4) Dose modification studies using [¹⁸F]FMISO PET are in a pilot phase.

Conclusions

Our results show that currently there is insufficient evidence to propose [¹⁸F]FMISO PET for radiotherapy dose adaptation in HNC in a routine clinical setting. Part of the challenge is that hypoxia is a dynamic phenomenon, and thus areas identified on a single scan may not be representative. At present, it is anticipated that [¹⁸F]FMISO PET will remain useful within the research setting only.

Magnetic resonance imaging (MRI) represents a gold standard imaging for detection of oncologic and non-oncologic musculoskeletal disorders (MSK), owing to its high soft tissue contrast. Positron Emission Tomography (PET) was proven to be clinically useful in MSK, owing to its early detection of metabolic disfunction and its high accuracy for monitoring therapy response. With hybrid PET/MRI system, simultaneous availability of both morphologic and metabolic features could potentially enhance the diagnostic accuracy in MSK. Some technical issue should be overcome for best imaging quality: specific MR sequences for accurate visualization of cortical bone and bone marrow involvement, such as zero-time echo (ZTE) or µ time echo (µTE) sequences, that were shown to provide valuable attenuation coefficients for the bone, which leads to accurate quantitative analysis of bone and extra-bone tissues; implementation of novel attenuation map, owing to the presence of flexible coils in the field of view, additional sequences to reduce artifacts derived from metal implants. Workflow consideration should be addressed to the choice of proper sequences able to answer the clinical demand or the research purpose. Redundant information provided by useless sequences, which could prolong the whole scan time and increase the discomfort of the patient, should be avoided.

Objective

The objective of this research is to conduct a thorough evaluation, both quantitatively and qualitatively, of the effectiveness of ⁶⁸Ga-Pentixafor PET within the Primary Aldosteronism framework.

Methods

We systematically searched the PubMed and Embase databases for relevant studies concerning the use of ⁶⁸Ga-Pentixafor PET in Primary Aldosteronism, spanning from the inception of these databases up to September 1, 2023. We assessed the quality of the chosen literature employing the QUADAS-2 diagnostic test evaluation tool. Following this, we conducted comprehensive analyses, both quantitatively and qualitatively, on relevant outcome measures extracted from the selected literature.

Results

This study incorporated 7 articles encompassing a total of 474 patients. Among these articles, seven studies assessed the accuracy of ⁶⁸Ga-Pentixafor PET in distinguishing between different subtypes of Primary Aldosteronism, namely aldosterone-producing adenoma and non-aldosterone-producing adenoma. Of these, four studies presented complete 2 × 2 contingency tables for visual analysis, and three studies provided complete 2 × 2 contingency tables for semi-quantitative analysis. In addition, six studies reported the correlation between ⁶⁸Ga-Pentixafor PET findings and the clinical characteristics of patients. Furthermore, five studies explored the relationship between ⁶⁸Ga-Pentixafor PET outcomes and the clinical prognosis of patients. Five studies also investigated the correlation between ⁶⁸Ga-Pentixafor PET results and immunohistochemistry, whereas four studies assessed the link between ⁶⁸Ga-Pentixafor PET and nodule size.

Conclusion

⁶⁸Ga-Pentixafor PET displays substantial promise in enhancing the diagnosis of Primary Aldosteronism subtypes and precisely localizing aldosterone-producing adenoma. Furthermore, ⁶⁸Ga-Pentixafor PET imaging exhibits significant correlations with the clinical characteristics, clinical prognosis, immunohistochemistry, and nodule size in Primary Aldosteronism patients.

Surgery is a key treatment for localized or locally advanced solid tumors. However, the application of wide safety margins can result in significant side effects and functional limitations for the patient. On the contrary, tissue-sparing surgery may leave residual tumor, which can lead to local recurrent cancer or distant metastases. To address these problems, intraoperative radio-guidance, such as beta radio-guided surgery (RGS), could be used to detect small cancerous tissue and selectively resect malignant areas. This paper provides a comprehensive review of RGS based on beta emission, focusing on the physical principles that differentiate beta radiation from gamma radiation, which is already commonly used in nuclear medicine. Although beta RGS was proposed several decades ago, its popularity has recently increased, possibly due to the widespread use of newly developed PET radiotracers. Various approaches are currently being investigated to assess the effectiveness of beta RGS, including the use of both beta+ and beta− emitting radiopharmaceuticals. Beta RGS has unique characteristics that make it a promising complementary technique to standard procedures. Encouraging results have been obtained in numerous ex vivo and in vivo tests. However, clinical trials are needed to demonstrate the real clinical value of these promising technologies. The references presented represent the most impactful works in the development of beta RGS, according to the authors. Papers were selected from a Scopus search with keywords “radio-guided surgery” and “beta emitter”.