Correlations between 18F-FDG PET/CT parameters and pathological findings in patients with rectal cancer. Clin Nucl Med. 2014;39:e40-e45. [PMID: 24335567 DOI: 10.1097/rlu.0b013e318292f0f6]

Radiologic T staging of colon cancer: renewed interest for clinical practice

Radiologic imaging, especially MRI, has long been the mainstay for rectal cancer staging and patient selection for neoadjuvant therapy prior to surgical resection. In contrast, colonoscopy and CT have been the standard for colon cancer diagnosis and metastasis staging with T and N staging often performed at the time of surgical resection. With recent clinical trials exploring the expansion of the use of neoadjuvant therapy beyond the anorectum to the remainder of the colon, the current and future state of colon cancer treatment is evolving with a renewed interest in evaluating the role radiology may play in the primary T staging of colon cancer. The performance of CT, CT colonography, MRI, and FDG PET-CT for colon cancer staging will be reviewed. N staging will also be briefly discussed. It is expected that accurate radiologic T staging will significantly impact future clinical decisions regarding the neoadjuvant versus surgical management of colon cancer.

Value of Primary Rectal Tumor PET/MRI in the Prediction of Synchronic Metastatic Disease

PURPOSE

To analyze the associations between positron emission tomography (PET)/magnetic resonance imaging (MRI) features for primary rectal tumors and metastases.

PROCEDURES

Between November 2016 and April 2018, 101 patients with rectal adenocarcinoma were included in this prospective study (NCT02537340) for whole-body PET/MRI for baseline staging. Two readers analyzed the PET/MRI; they assessed the semiquantitative PET features of the primary tumor and the N- and M-stages. Another reader analyzed the MRI features for locoregional staging. The reference standard for confirming metastatic disease was biopsy or imaging follow-up. Non-parametric tests were used to compare the PET/MRI features of the participants with or without metastatic disease. Binary logistic regression was used to evaluate the associations between the primary tumor PET/MRI features and metastatic disease.

RESULTS

A total of 101 consecutive participants (median age 62 years; range: 33-87 years) were included. Metastases were detected in 35.6% (36 of 101) of the participants. Among the PET/MRI features, higher tumor lesion glycolysis (352.95 vs 242.70; P = .46) and metabolic tumor volume (36.15 vs 26.20; P = .03) were more frequent in patients with than in those without metastases. Additionally, patients with metastases had a higher incidence of PET-positive (64% vs 32%; P = .009) and MRI-positive (56% vs 32%; P = .03) mesorectal lymph nodes, extramural vascular invasion (86% vs 49%; P > .001), and involvement of mesorectal fascia (64% vs 42%; P = .04); there were also differences between the mrT stages of these two groups (P = .008). No differences in the maximum standardized uptake values for the primary tumors in patients with and without metastases were observed (18.9 vs 19.1; P = .56). Multivariable logistic regression showed that extramural vascular invasion on MRI was the only significant predictor (adjusted odds ratio, 3.8 [95% CI: 1.1, 13.9]; P = .001).

CONCLUSION

PET/MRI facilitated the identification of participants with a high risk of metastatic disease, though these findings were based mainly on MRI features.

Colorectal cancer: Parametric evaluation of morphological, functional and molecular tomographic imaging

Colorectal cancer (CRC) represents one of the leading causes of tumor-related deaths worldwide. Among the various tools at physicians’ disposal for the diagnostic management of the disease, tomographic imaging (e.g., CT, MRI, and hybrid PET imaging) is considered essential. The qualitative and subjective evaluation of tomographic images is the main approach used to obtain valuable clinical information, although this strategy suffers from both intrinsic and operator-dependent limitations. More recently, advanced imaging techniques have been developed with the aim of overcoming these issues. Such techniques, such as diffusion-weighted MRI and perfusion imaging, were designed for the “in vivo” evaluation of specific biological tissue features in order to describe them in terms of quantitative parameters, which could answer questions difficult to address with conventional imaging alone (e.g., questions related to tissue characterization and prognosis). Furthermore, it has been observed that a large amount of numerical and statistical information is buried inside tomographic images, resulting in their invisibility during conventional assessment. This information can be extracted and represented in terms of quantitative parameters through different processes (e.g., texture analysis). Numerous researchers have focused their work on the significance of these quantitative imaging parameters for the management of CRC patients. In this review, we aimed to focus on evidence reported in the academic literature regarding the application of parametric imaging to the diagnosis, staging and prognosis of CRC while discussing future perspectives and present limitations. While the transition from purely anatomical to quantitative tomographic imaging appears achievable for CRC diagnostics, some essential milestones, such as scanning and analysis standardization and the definition of robust cut-off values, must be achieved before quantitative tomographic imaging can be incorporated into daily clinical practice.

Positron emission tomography with computed tomography imaging (PET/CT) for the radiotherapy planning definition of the biological target volume: PART 2

AIM

Positron Emission Tomography with Computed Tomography (PET/CT) has been proven to be useful in the definition of Radiotherapy (RT) target volume. In this regard, the present expert review summarizes existing data for pancreas, prostate, gynecological and rectum/anal cancer.

METHODS

A comprehensive search of published original article was made, based on SCOPUS and PubMed database, selecting the paper that evaluated the role of PET/CT in the definition of RT volume.

RESULTS

FDG-PET has an important and promising role for pancreatic cancer. Choline PET/CT could be useful for identifying high-risk volumes for prostate cancer; while PSMA PET/CT is still under evaluation. FDG PET/CT in gynecological cancers has been shown to impact external-beam RT planning. The role of FDG-PET for Gross Tumor volume identification is crucial, representing a useful and powerful tool for anal and rectal cancer.

CONCLUSION

Taken together, molecular and functional imaging approaches offer a major step to individualize radiotherapeutic approach.

The predictive value of metabolic tumor volume on FDG PET/CT for transarterial chemoembolization and transarterial chemotherapy infusion in hepatocellular carcinoma patients without extrahepatic metastasis

OBJECTIVE

The aim of this study was to evaluate the prognostic value of metabolic tumor volume (MTV) on pre-treatment F-18 fluorodeoxyglucose (FDG) PET/CT in patients with hepatocellular carcinoma (HCC).

METHODS

A total of 59 HCC patients who underwent FDG PET/CT before transarterial chemoembolization (TACE) or transarterial chemotherapy infusion (TACI) were retrospectively enrolled. The region of interest was drawn in the HCC and normal liver tissue. MTV2SD, defined as the sum of the voxels with higher standardized uptake values (SUV) than the SUV of the 97.5th percentile of voxels of the normal liver for each patient, was calculated using an intensity-volume histogram (IVH). The ratio of the maximum SUV of the tumor to the mean SUV of normal liver (T max/L mean) was also calculated. The prognostic significance of MTV2SD and Tmax/Lmean for progression-free survival (PFS) and overall survival (OS) was evaluated along with other clinical factors.

RESULTS

The tumor number, Tmax/Lmean, and MTV2SD were significant prognostic factors affecting PFS (p < 0.05), whereas tumor number, serum alpha-fetoprotein level, tumor stage, portal vein thrombosis, Tmax/Lmean, and MTV2SD were significant prognostic factors for OS (p < 0.05). In multivariate analysis, the tumor number and MTV2SD were independent prognostic factors for PFS (p < 0.05), whereas the independent prognostic factors for OS were tumor number, tumor stage, and MTV2SD (p < 0.05). The mean PFS and OS in patients with low MTV2SD (15.4 and 63.1 months, respectively) were significantly longer than those in patients with high MTV2SD (6.0 and 15.2 months, respectively; p = 0.005 and p < 0.0001, respectively).

CONCLUSIONS

Metabolic tumor volume was an independent prognostic factor for PFS and OS in patients with HCC. Therefore, FDG PET/CT can provide valuable prognostic information for HCC patients who undergo TACE or TACI.