The use of 18F-FDG PET/CT in colorectal liver metastases--comparison with CT and liver MRI

Micro-Nano Convergence-Driven Radiotheranostic Revolution in Hepatocellular Carcinoma

Radiotherapy, as an important means of treating hepatocellular carcinoma (HCC), has shown unique therapeutic advantages, especially in patients who are unable to undergo surgery or transplantation. It mainly includes external radiotherapy, transarterial radioembolization and intratumoral radioactive particle implantation. However, under the influence of factors such as the hypoxic characteristics of the liver tumor microenvironment and the radioresistance of tumor cells, the effect of radiotherapy may be unstable and may cause side effects, affecting the quality of life of patients. In recent years, with the development of nanotechnology, drug delivery systems based on micro-nanomaterials have provided new solutions for improving the effect of radiotherapy for HCC. Despite this, the application of micro-nano drug delivery systems in the treatment of HCC still faces some challenges, mainly including the in vivo safety and in vivo metabolism of micro-nano materials. This article reviews the latest progress of micro-nano materials in the treatment of HCC, especially their application in radiosensitization and their clinical translation potential. This article systematically analyzes the role of micro-nanomaterials in external or internal radiotherapy sensitization and radioimmunotherapy and explores the advantages of micro-nanomaterials in improving the treatment effect of HCC.

PET-based Quantitative Techniques in Assessing Efficacy of Interventional Radiology Procedures in Oncology

Interventional radiology (IR) is a super specialised branch where imaging modalities are employed to guide disease specific diagnostic and therapeutic interventions. IR interventions have gained popularity in various oncological and non-oncological indications due to it's ability to effectively diagnose the disease and direct specific targeted treatment. Hybrid imaging using PET CT and PET MRI combines the best of morphological and functional informations and offers improved sensitivity and specificity for detection of lesion; helps in accurate mapping of tumour burden, thereby aiding in planning curative vs palliative intent intervention; more accurate response evaluation to plan redo session in cases of residual / recurrent disease or for follow up evaluation and for prognostication and predicting response. Albeit visual analysis of PET images by specialist is most commonly performed for reading PET scans, PET has a remarkable capability to provide quantitative information. The present review provides a comprehensive assessment of the role of various aspects of quantitative PET parameters in assessing the efficacy of IR interventions. The insights provided will help clinicians, researchers, and medical professionals understand the role of PET imaging in advancing patient care and enhancing the therapeutic outcomes of IR procedures.

Head-to-head comparison of [68Ga]Ga-FAPI PET and [18F]FDG PET in the detection of bone and lymph node metastasis in various cancers: A systematic review and meta-analysis

PURPOSE

The aim of our meta-analysis and systematic review was to contrast the positivity rates of [68Ga]Ga-FAPI PET and [18F]FDG PET in detecting bone and lymph node metastases across diverse cancer types.

METHODS

We conducted a comprehensive search for eligible articles up until August 2023, utilizing databases including PubMed, Embase, and Web of Science. Studies focusing on the positivity rate of [68Ga]Ga-FAPI PET vs. [18F]FDG PET for bone and lymph metastasis were included. Using random-effect model, the positivity rate for [68Ga]Ga-FAPI PET and [18F]FDG PET were generated. In order to gauge the heterogeneity among aggregated studies, we utilized the I2 statistic. Additionally, we applied the Quality Assessment of Diagnostic Performance Studies (QUADAS-2) methodology to evaluate the caliber of the studies encompassed in our analysis.

RESULTS

A total of 430 publications were initially identified in the search. Eventually, 25 studies, involving 779 patients, met the inclusion criteria. In terms of bone metastasis, the findings indicate no statistically significant difference between the use of [68Ga]Ga-FAPI PET and [18F]FDG PET (P = 0.34). However, concerning lymph node metastasis, the results demonstrate significant difference between the two imaging agents (P = 0.04).

CONCLUSIONS

This systematic review suggests that [68Ga]Ga-FAPI PET appears to outperform [18F]FDG PET in detecting lymph node metastases. However, when it comes to bone metastasis, no statistically significant difference was observed. It is crucial to acknowledge that the insights concerning bone metastasis stem from studies with comparatively modest sample sizes. Consequently, there is a pressing demand for further, expansive prospective studies in this field.

Impact of positron-emission tomography on the surgical treatment of locoregionally recurrent colorectal cancer

BACKGROUND

The effect of positron emission tomography (PET) on the surgical treatment of locoregionally recurrent colorectal cancer (LRRCRC) remains unclear and warrants further investigation.

MATERIAL AND METHODS

A total of 193 patients with LRRCRC were identified from a prospectively maintained institutional database, of whom 134 LRRCRCs were deemed resectable and underwent resection with curative intent, whereas the remaining 59 LRRCRCs were unresectable. Patients with resectable LRRCRC were further classified according to whether recurrence was detected solely by PET (n = 35, PET-only group) or by a combination of computed tomography (CT)/magnetic resonance imaging (MRI) and PET (n = 99, CT/MRI/PET group). Clinicopathologic features, operative morbidity/mortality, and overall survival were compared between the patient groups based on long-term follow-up for at least 5 years.

RESULTS

Patients in the PET-only group tended to have less extensive organ resection (p = 0.0074), less blood loss (p < 0.0001), and shorter operation time and hospitalization (p < 0.0001), but surgical complication and readmission rates were not significantly different (p > 0.05) compared with the CT/MRI/PET group. Although the PET-only group had significantly higher R0 resection rate (80 % vs. 54.55 %, p = 0.0079), they also had a higher risk (17.14 % vs. 2.02 %, p = 0.0011) of sham operation. The estimated 5-year and 10-year survival rates significantly decreased in order (p < 0.0001) from PET-only (85.71 % and 57.98 %) and CT/MRI/PET (41.41 % and 15.93 %) to unresectable group of patients (16.95 % and 1.88 %). Subset analysis of the CT/MRI/PET group indicated that PET improved surgical decision-making because 24 (24.2 %) LRRCRCs that manifested on CT/MRI as equivocal lesions were later confirmed by PET as resectable recurrences, while 18 (19.4 %) LRRCRCs that manifested on CT/MRI as resectable lesions were later diagnosed by PET as more disseminated unresectable recurrences and precluded futile surgery.

CONCLUSION

PET alone can identify a subset (20.9 %) of LRRCRCs with less tumor burden for timely surgery; PET in combination with CT/MRI can better define the resectability of LRRCRCs. The positive impacts of PET can translate into better surgical outcomes, with enhanced safety and patient survival.

Beyond CT: A Case Analysis of Serial [18F]FDG PET/CT for Assessment of Necrosis and Early Recurrence in Colorectal Liver Metastases

Colorectal cancer is a common malignancy, with the liver being the most frequent site of metastases. [18F] Fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) has emerged as a valuable tool in detecting and evaluating liver metastases and extrahepatic disease. Herein, we present a case of a 76-year-old male with colorectal cancer associated with lung and liver metastases. The patient received 12 chemoimmunotherapy cycles and was then put on maintenance cetuximab; serial [18F]FDG PET/CT scans were utilized to evaluate treatment response. The patient exhibited a positive response to chemoimmunotherapy, with regression of rectal disease and resolution of pulmonary metastatic nodules. Serial [18F]FDG PET/CT scans unveiled three distinct necrotic patterns. The case report advocates that [18F]FDG PET/CT plays an important role in evaluating colorectal liver metastases (CRLM) response to treatment, identifying transient necrosis, early recurrence, and emphasizing the limitations of post-treatment CT scans in identifying early CRLM recurrence. Integrating functional imaging, particularly [18F]FDG PET/CT, promises for management monitoring and surveillance of CRLM patients.

[18F]FDG PET/CT versus [18F]FDG PET/MRI for the diagnosis of colorectal liver metastasis: A systematic review and meta-analysis

Purpose

The purpose of our meta-analysis and systematic review was to compare the diagnostic performance of [18F]FDG PET/CT and [18F]FDG PET/MRI in colorectal liver metastasis.

Methods

We searched PubMed, Embase, and Web of Science for eligible articles until November 2022. Studies focusing on the diagnostic value of [18F]FDG PET/CT or PET/MRI for colorectal liver metastasis were included. Using a bivariate random-effect model, the pooled sensitivity and specificity for [18F]FDG PET/CT and [18F]FDG PET/MRI were reported as estimates with 95% confidence intervals (CIs). Heterogeneity among pooled studies was assessed using the I² statistic. The Quality Assessment of Diagnostic Performance Studies (QUADAS-2) method was used to evaluate the quality of the studies that were included.

Results

There were a total of 2743 publications identified in the initial search, finally, a total of 21 studies comprising 1036 patients were included. The pooled sensitivity, specificity, and AUC of [18F]FDG PET/CT in were 0.86 (95% CI: 0.76-0.92), 0.89 (95% CI: 0.83-0.94), and 0.92(95% CI: 0.90-0.94). [18F]FDG PET/MRI were 0.84 (95% CI: 0.77-0.89), 1.00 (95% CI: 0.32-1.00), and 0.89(95% CI: 0.86-0.92), respectively.

Conclusion

[18F]FDG PET/CT shows similar performance compared to [18F]FDG PET/MRI in detecting colorectal liver metastasis. However, pathological results were not obtained for all patients in the included studies and PET/MRI results were derived from studies with small sample sizes. There is a need for additional, larger prospective studies on this issue.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier (CRD42023390949).

Clinical value of fluorine-18-fluorodeoxyglucose PET/MRI for liver metastasis in colorectal cancer: a prospective study

PURPOSE

To evaluate the diagnostic performance of liver 18F-FDG PET/MRI in addition to whole-body PET/CT and to compare it with MRI in the detection and clinical management of liver metastasis in patients with colorectal cancer (CRC).

MATERIAL AND METHODS

Seventy-eight patients with CRC who underwent whole-body 18F-FDG PET/CT followed by liver PET/MRI were prospectively included. Histopathological confirmation and/or at least 3 months of clinical follow-up after PET/MRI were accepted as gold standard. Lesion and patient-based analyses were performed to evaluate the diagnostics performances of PET/CT, PET/MRI and MRI. In addition, changes of clinical management were evaluated.

RESULTS

On lesion-based analysis, for PET/CT, PET/MRI and MRI; sensitivity (Se): 55.6%, 97.2% and 100%; specificity (Sp): 98.5%, 100% and 80.5%; and accuracy (Acc): 70.7%, 98.2% and 93.1% were calculated, respectively. Se and Acc of PET/MRI and MRI were significantly superior than PET/CT (P < 0.001). Se and Acc of PET/MRI and MRI were comparable; however, Sp of PET/MRI was significantly better than MRI (P < 0.001). On patient-based analysis, Se: 75.6%, 100% and 100%; Sp: 97.3%, 100% and 86.5%; and Acc: 85.9%, 100% and 93.5% were calculated, respectively. Se and Acc of PET/MRI were significantly superior than PET/CT (P < 0.001). Also, Se of MRI was significantly superior than PET/CT (P < 0.001). Se of PET/MRI and MRI were comparable, but Sp and Acc of PET/MRI were significantly better than MRI. The additional information obtained from liver PET/MRI changed treatment strategy in 14/78 (18%) patients compared to PET/CT or alone liver MRI.

CONCLUSION

Diagnostic performances of PET/MRI and MRI for detection of CRC liver metastasis is superior to PET/CT. PET/MRI especially helps in the accurate detection of liver metastases that are suspicious on MRI and has the potential to change the clinical management of especially oligometastatic patients by identifying uncertain liver lesions.

Real-Time Split-Dose PET/CT-Guided Ablation Improves Colorectal Liver Metastasis Detection and Ablation Zone Margin Assessments without the Need for Repeated Contrast Injection

BACKGROUND

Real-time split-dose PET can identify the targeted colorectal liver metastasis (CLM) and eliminate the need for repeated contrast administration before and during thermal ablation (TA). This study aimed to assess the added value of pre-ablation real-time split-dose PET when combined with non-contract CT in the detection of CLM for ablation and the evaluation of the ablation zone and margins.

METHODS

A total of 190 CLMs/125 participants from two IRB-approved prospective clinical trials using PET/CT-guided TA were analyzed. Based on detection on pre-TA imaging, CLMs were categorized as detectable, non-detectable, and of poor conspicuity on CT alone, and detectable, non-detectable, and low FDG-avidity on PET/CT after the initial dose. Ablation margins around the targeted CLM were evaluated using a 3D volumetric approach.

RESULTS

We found that 129/190 (67.9%) CLMs were detectable on CT alone, and 61/190 CLMs (32.1%) were undetectable or of poor conspicuity, not allowing accurate depiction and targeting by CT alone. Thus, the theoretical 5- and 10-mm margins could not be defined in these tumors (32.1%) using CT alone. When TA intraprocedural PET/CT images are obtained and inspected (fused PET/CT), only 4 CLM (2.1%) remained undetectable or had a low FDG avidity.

CONCLUSIONS

The addition of PET to non-contrast CT improved CLM detection for ablation targeting, margin assessments, and continuous depiction of the FDG avid CLMs during the ablation without the need for multiple intravenous contrast injections pre- and intra-procedurally.

Non-invasive detection and complementary diagnosis of liver metastases via chemokine receptor 4 imaging

Noninvasive detection of early-stage liver metastases from different primary cancers is a pressing unmet medical need. The lack of both molecular biomarkers and the sensitive imaging methodology makes the detection challenging. In this study, we observed the elevated expression of chemokine receptor 4 (CXCR4) in uveal melanoma (UM) patient liver tissues, and high CXCR4 expression in liver metastases of UM murine models, regardless of the expression levels in the primary tumors. Based on these findings, we identified CXCR4 as an imaging biomarker and exploited a CXCR4-targeted MRI contrast agent ProCA32.CXCR4 for molecular MRI imaging. ProCA32.CXCR4 has strong CXCR4 binding affinity, high metal selectivity, and r1 and r2 relaxivities, which enables the sensitive detection of liver micrometastases. The MRI imaging capacity for detecting liver metastases was demonstrated in three UM models and one ovarian cancer model. The imaging results were validated by histological and immunohistochemical analysis. ProCA32.CXCR4 has strong potential clinical application for non-invasive diagnosis of liver metastases.

Does 18F-FDG PET/CT change the surgical management of potentially resectable colorectal liver metastases?

PURPOSE

Resectability assessment of patients with colorectal liver metastases is based on computed tomography and liver magnetic resonance imaging. Addition of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography has been recommended, but the impact of the added information remains unclear. The primary aim of this study was to determine how preoperative positron emission tomography/computed tomography changed management in patients with potentially resectable colorectal liver metastases. The secondary aim was to investigate whether findings on positron emission tomography/computed tomography correlated to metastatic disease in cases with extended surgery and influenced oncological outcomes.

METHODS

A retrospective observational study of the impact of adding positron emission tomography/computed tomography to conventional imaging in the surgical decision-making of colorectal liver metastases. All patients with colorectal liver metastases diagnosed by conventional imaging were included and assessed by a multidisciplinary team conference at Umeå University Hospital between June 2013 and December 2017. Eligibility criteria were all patients with potentially resectable colorectal liver metastases. Patients who underwent preoperative positron emission tomography/computed tomography in addition to conventional radiology were compared with those who underwent conventional imaging only.

RESULTS

151/220 patients underwent preoperative positron emission tomography/computed tomography. Findings on positron emission tomography/computed tomography changed the management in 10.6% of the patients. Eight patients were excluded from surgery after detection by positron emission tomography/computed tomography of extrahepatic disease. Eight patients underwent more extended surgery than initially planned due to positron emission tomography/computed tomography. Five of these positron emission tomography-positive resected sites were verified by pathology as metastatic disease. No difference in overall survival was seen following surgical resection in patients with and without a preoperative positron emission tomography/computed tomography.

CONCLUSIONS

Preoperative positron emission tomography/computed tomography resulted in a changed surgical management in 10.6% of cases in a selected cohort.

The Course of LIRADS 3 and 4 Hepatic Abnormalities as Correlated With Explant Pathology: A Single Center Experience

BACKGROUND AND AIMS

The Liver Reporting and Data System (LI-RADS) is the standard classification of imaging findings of hepatic abnormalities for hepatocellular carcinoma (HCC) surveillance. We aimed to study the course of LI-RADS 3 and 4 (LR-3 and LR-4) abnormalities through correlations with explant pathology.

METHODS

A single center retrospective study of liver transplant recipients between January 2016 and September 2019 with HCC on explant pathology was conducted. Eligible patients were divided into three subgroups based on their LI-RADS classification: LR-3/4, LR-5 only, and combination of LR-3/4/5.

RESULTS

There were 116 eligible patients with 99 LR-3/4 observations (60 LR-3 and 39 LR-4); the rest had LR-5 lesions. LR-4 more often than LR-3 observations progressed to LR-5 (36% vs 12%) and with shorter duration during follow-up (median 175 days and 196 days). Mean size growth of LR-3 and LR-4 abnormalities were 2.6 and 3.8 mm; median growth rates were 0.2 and 0.4 mm/month, respectively. Numbers of HCC lesions per explant, largest HCC lesion size, and cumulative size were higher in LR-3/4/5 subgroup than LR-5 subgroup (P = 0.007, 0.007 and 0.006, respectively); 68% of LR-3 and 82% of LR-4 abnormalities were confirmed HCC on explant (P = 0.09).

CONCLUSION

Compared to LR-3, more LR-4 abnormalities progressed to LR-5 (12% and 36%, respectively) in a shorter time and with faster growth rate. A high proportion of LR-3 and LR-4 lesions (68% and 82%, respectively) were confirmed HCC on explant, raising the question of whether excluding HCC based on radiologic criteria alone is adequate in those with LR-3/4 abnormalities.

Multimodality Approach in Detection and Characterization of Hepatic Metastases

Early detection of liver metastases is important in patients with known primary malignancies. This plays an important role in treatment planning and impacts on further management of certain primary malignancies.

Magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography-computed tomography scans are reported to have high accuracy in the diagnosis of intrahepatic lesions. MRI in particular has the advantages of its high tissue sensitivity and its multiparametric approach.

Hepatic metastatic lesions have considerable overlap in their radiological appearance, and in this article the imaging appearance of various hepatic metastasis and approach is described.

Current state of the art imaging approaches for colorectal liver metastasis

One of the most common cancers worldwide, colorectal cancer (CRC) has been associated with significant morbidity and mortality and therefore represents an enormous burden to the health care system. Recent advances in CRC treatments have provided patients with primary and metastatic CRC a better long-term prognosis. The presence of synchronous or metachronous metastasis has been associated, however, with worse survival. The most common site of metastatic disease is the liver. A variety of treatment modalities aimed at targeting colorectal liver metastases (CRLM) has been demonstrated to improve the prognosis of these patients. Loco-regional approaches such as surgical resection and tumor ablation (operative and percutaneous) can provide patients with a chance at long-term disease control and even cure in select populations. Patient selection is important in defining the most suitable treatment option for CRLM in order to provide the best possible survival benefit while avoiding unnecessary interventions and adverse events. Medical imaging plays a crucial role in evaluating the characteristics of CRLMs and disease resectability. Size of tumors, proximity to adjacent anatomical structures, and volume of the unaffected liver are among the most important imaging parameters to determine the suitability of patients for surgical management or other appropriate treatment approaches. We herein provide a comprehensive overview of current-state-of-the-art imaging in the management of CRLM, including staging, treatment planning, response and survival assessment, and post-treatment surveillance. Computed tomography (CT) scan and magnetic resonance imaging (MRI) are two most commonly used techniques, which can be used solely or in combination with functional imaging modalities such as positron emission tomography (PET) and diffusion weighted imaging (DWI). Providing up-to-date evidence on advantages and disadvantages of imaging modalities and tumor assessment criteria, the current review offers a practice guide to assist providers in choosing the most suitable imaging approach for patients with CRLM.

Diagnostic performance of magnetic resonance imaging for colorectal liver metastasis: A systematic review and meta-analysis

The prognosis of colorectal cancer (CRC) is largely dependent on the early detection of hepatic metastases. With the advantages of nonradioactivity and the availability of multiple scanning sequences, the efficacy of magnetic resonance imaging (MRI) in the detection of colorectal liver metastases (CRLM) is not yet clear. We performed this meta-analysis to address this issue. PubMed, Embase, and the Cochrane Library were searched for studies reporting diagnostic performance of MRI for CRLM. Descriptive and quantitative data were extracted. The study quality was evaluated for the identified studies and a random effects model was used to determine the integrated diagnosis estimation. Meta-regression and subgroup analyses were implemented to investigate the potential contributors to heterogeneity. As a result, seventeen studies were included for analysis (from the year 1996 to 2018), comprising 1121 patients with a total of 3279 liver lesions. The pooled sensitivity, specificity, and diagnostic odds ratio were 0.90 (95% confidence intervals (CI): 0.81-0.95), 0.88 (0.80-0.92), and 62.19 (23.71-163.13), respectively. The overall weighted area under the curve was 0.94 (0.92-0.96). Using two or more imaging planes and a quantitative/semiquantitative interpretation method showed higher diagnostic performance, although only the latter demonstrated statistical significance (P < 0.05). Advanced scanning sequences with DWI and liver-specific contrast media tended to increase the sensitivity for CRLM detection. We therefore concluded that contemporary MRI has high sensitivity and specificity for screening CRLM, especially for those with advanced scanning sequences. Using two or more imaging planes and adopting a quantitative/semiquantitative imaging interpretation may further improve diagnosis. However, the MRI results should be interpreted with caution because of substantial heterogeneity among studies.

[Importance of FDG-PET/computed tomography in colorectal cancer]

BACKGROUND

Hybrid imaging FDG PET/CT (¹⁸F‑fluordeoxyglucose positron emission tomography/computed tomography) has gained increasing importance in oncology in recent years.

DIAGNOSIS

A focal increase in FDG uptake in the gastrointestinal tract may be due to colorectal carcinoma. Such a finding requires further clarification.

PRIMARY STAGING

Staging of the primary and locoregional lymph nodes remains a domain of established imaging modalities as FDG PET/CT does not provide a clear additional benefit. Liver metastases can be detected with high sensitivity by FDG PET/CT, but MRI is superior in small lesions.

RADIATION THERAPY PLANNING

So far FDG PET/CT plays a subordinate role in the radiation therapy planning of rectal cancer. However, it can potentially contribute to the optimization of planning target volumes.

THERAPY MONITORING

FDG PET/CT is suitable for monitoring therapy because morphological and metabolic changes of the tumor can be detected in early stages. This enables early detection of nonresponders after beginning neoadjuvant chemoradiation therapy of rectal cancer. FDG PET/CT can also be used for therapy control of liver metastases, especially after local therapeutic procedures.

DETECTION OF RECURRENCE

With clinical suspicion of local recurrence and increased tumor markers, FDG PET/CT is a valuable tool as tumor recurrence can be detected with high sensitivity and specificity.

Efficacy of contrast-enhanced FDG PET/CT in patients awaiting liver transplantation with rising alpha-fetoprotein after bridge therapy of hepatocellular carcinoma

OBJECTIVE

To assess the diagnostic accuracy and illustrate positive findings of contrast-enhanced fluorine-18 fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) image in patients awaiting liver transplantation (LT) with rising alpha-fetoprotein (AFP) after bridge therapy of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

This prospective study included 100 patients who were waiting for LT and who previously underwent locoregional therapy (LRT) of HCC. These patients had rising AFP levels on a routine follow-up examination awaiting LT. All patients underwent a contrast-enhanced 18F-FDG PET/CT examination. We calculated for each patient the maximum standardised uptake value (SUVmax) of the tumour and the ratio of the tumoral SUVmax to the normal-liver SUVmax. The diagnostic accuracy and positive contrast-enhanced findings of 18F-FDG PET/CT were established by histopathology and clinical and imaging follow-up as the reference standards.

RESULTS

Contrast-enhanced 18F-FDG PET/CT detected tumour relapse in 78 patients (13 patients had intrahepatic lesions, 10 patients had extrahepatic metastases and 55 patients with combined lesions). The sensitivity, specificity and accuracy values of contrast-enhanced 18F-FDG PET/CT examination in the detection of HCC recurrence were 92.8%, 94.1% and 93%, respectively. A significant correlation was found between the AFP level and SUVmax ratio (r = 0.2283; p = 0.0224). The best threshold for 18F-FDG PET positivity was >1.21.

CONCLUSION

Contrast-enhanced 18F-FDG PET/CT is a valuable tool for the detection of intrahepatic HCC recurrence or extrahepatic metastasis following rising AFP levels after LRT of HCC, and should be incorporated during routine workup awaiting LT.

KEY POINTS

• 18F-FDG PET/CT is a valuable tool for the detection of HCC recurrence • 18 F-FDG PET/CT should be incorporated during routine workup awaiting liver transplantation • Significant correlation was found between AFP level and SUVmax ratio • The best threshold for 18 F-FDG PET positivity was >1.21 • The ideal cut-off value for AFP was >202.

Imaging for Peritoneal Metastases

MRI provides considerable advantages for imaging of patients with peritoneal tumor. Its inherently superior contrast resolution compared with computed tomography allows MRI to more accurately depict small peritoneal tumors that are often missed on other imaging tests. Combining different contrast mechanisms, including diffusion-weighted MRI and gadolinium-enhanced MRI, provides a powerful tool for preoperative and surveillance imaging in patients being considered for cytoreductive surgery and heated intraperitoneal chemotherapy.

Diagnostic performance of CT, gadoxetate disodium-enhanced MRI, and PET/CT for the diagnosis of colorectal liver metastasis: Systematic review and meta-analysis

BACKGROUND

Imaging studies, including computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), have an essential role in the detection and localization of colorectal liver metastasis (CRLM).

PURPOSE

To systematically determine the diagnostic accuracy of multidetector row CT (MDCT), gadoxetate disodium-enhanced MRI, and PET/CT for diagnosing CRLM and the sources of heterogeneity between the reported results.

STUDY TYPE

Systematic review and meta-analysis.

SUBJECTS

In all, 2151 lesions in CT studies, 2301 lesions in MRI studies, 1846 lesions in PET/CT studies, FIELD STRENGTH: 1.5T and 3.0T.

ASSESSMENT

We identified research studies that investigated MDCT, gadoxetate disodium-enhanced MRI, and PET/CT to diagnose CRLM by performing a systematic search of PubMed MEDLINE and EMBASE. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2).

STATISTICAL TESTS

According to the types of imaging tests, study heterogeneity and the threshold effect were analyzed and the meta-analytic summary of sensitivity and specificity were estimated. Meta-regression analysis was performed to further investigate study heterogeneity.

RESULTS

Of the 860 articles screened, we found 36 studies from 24 articles reporting a diagnosis of CRLM (11 CT studies, 12 MRI studies, and 13 PET/CT studies). The meta-analytic summary sensitivity for CT, MRI, and PET/CT were 82.1% (95% confidence interval [CI], 74.0-88.1%), 93.1% (95% CI, 88.4-96.0%), and 74.1% (95% CI, 62.1-83.3%), respectively. The meta-analytic summary specificity for CT, MRI, and PET/CT were 73.5% (95% CI, 53.7-86.9%), 87.3% (95% CI, 77.5-93.2%), and 93.9% (95% CI, 83.9-97.8%), respectively. There was no threshold effect in any of the imaging tests. Neoadjuvant chemotherapy significantly decreased the sensitivity of CT and MRI (P < 0.01), although it did not significantly affect the sensitivity of PET/CT. The study design, type of reference standard, and study quality also affected the diagnostic performances of imaging studies.

DATA CONCLUSION

Despite the heterogeneous accuracy between studies, gadoxetate disodium-enhanced MRI showed the highest sensitivity, and gadoxetate disodium-enhanced MRI and PET/CT had similar specificities for diagnosing CRLM.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1237-1250.

Incidence and predictors of synchronous liver metastases in patients with gastrointestinal stromal tumors (GISTs)

BACKGROUND

The liver is the most common metastatic site in patients with gastrointestinal stromal tumors (GISTs). The purpose of this study is to identify the incidence and predictive factors associated with synchronous liver metastases among patients with GISTs.

METHODS

A retrospective review of the Surveillance Epidemiology and End Results (SEER) database was performed.

RESULTS

Overall, 2757 patients were identified, of which 276 (10%) had synchronous liver metastases. The two-year survival of patients with synchronous liver metastases was 31.9% overall and 37.1% after undergoing surgery with curative intent. Primary tumor size >5 cm (5-10 cm: OR 2.97, 95% CI: 1.03-8.55, p = 0.044, >10 cm: OR 5.59, 95% CI: 1.95-16.07, p = 0.001), presence of nodal metastases (OR 4.09, 95% CI: 2.01-8.33, p < 0.001) and mitotic count >5/50 HPF (OR 1.58, 95% CI: 1.01-2.47, p = 0.044) were associated with the presence of liver metastases.

CONCLUSIONS

One out of ten patients with GISTs presents with hepatic metastases. Primary tumor size >5 cm, presence of nodal metastases and mitotic count >5/50 HPF are associated with a higher risk of synchronous hepatic metastases.

Colorectal cancer staging: comparison of whole-body PET/CT and PET/MR

PURPOSE

Correct staging is imperative for colorectal cancer (CRC) since it influences both prognosis and management. Several imaging methods are used for this purpose, with variable performance. Positron emission tomography-magnetic resonance (PET/MR) is an innovative imaging technique recently employed for clinical application. The present study was undertaken to compare the staging accuracy of whole-body positron emission tomography-computed tomography (PET/CT) with whole-body PET/MR in patients with both newly diagnosed and treated colorectal cancer.

METHODS

Twenty-six patients, who underwent same day whole-body (WB) PET/CT and WB-PET/MR, were evaluated. PET/CT and PET/MR studies were interpreted by consensus by a radiologist and a nuclear medicine physician. Correlations with prior imaging and follow-up studies were used as the reference standard. Correct staging was compared between methods using McNemar's Chi square test.

RESULTS

The two methods were in agreement and correct for 18/26 (69%) patients, and in agreement and incorrect for one patient (3.8%). PET/MR and PET/CT stages for the remaining 7/26 patients (27%) were discordant, with PET/MR staging being correct in all seven cases. PET/MR significantly outperformed PET/CT overall for accurate staging (P = 0.02).

CONCLUSION

PET/MR outperformed PET/CT in CRC staging. PET/MR might allow accurate local and distant staging of CRC patients during both at the time of diagnosis and during follow-up.

Does positron emission tomography/computed tomography change management in colorectal cancer?

BACKGROUND

Positron emission tomography/computed tomography (PET/CT) is used pre-operatively in patients with metastatic or recurrent colorectal cancer to identify those who have potentially curative disease. However, a recent randomized trial questioned the added benefit of PET/CT over conventional imaging in patients with liver metastases. The aim of this study was to determine the proportion of patients with colorectal cancer in whom PET/CT altered surgical management, in a single tertiary centre.

METHODS

This was a retrospective study of all patients with colorectal cancer who had a PET/CT for colorectal cancer, funded by the Canterbury District Health Board between 2010 and 2014.

RESULTS

Some 111 PET/CT scans were performed on 105 patients. A total of 38% of PET/CT were for patients with known or suspected liver metastases, 23% for suspected local recurrence and 18% for known or suspected lung metastases. Five scans were for post-operative patients with a rising carcinoembryonic antigen and no attributable source on conventional imaging. PET/CT identified additional extrahepatic sites of disease in 19 of 111 (17%) scans in patients deemed to have potentially operable disease. Overall, PET/CT altered surgical management following six of 42 (14%) scans for patients with liver metastases, four of 20 (20%) scans for patients with lung metastases and six of 26 (23%) scans for patients with local recurrence.

CONCLUSION

PET/CT remains a useful adjunct to conventional imaging in the pre-operative workup of patients with colorectal cancer.

PET/CT in paediatric malignancies - An update

¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established imaging modality in adult oncological practice. Its role in childhood malignancies needs to be discussed as paediatric malignancies differ from adults in tumor subtypes and they have different tumor biology and FDG uptake patterns. This is also compounded by smaller body mass, dosimetric restrictions, and physiological factors that can affect the FDG uptake. It calls for careful planning of the PET study, preparing the child, the parents, and expertise of nuclear physicians in reporting pediatric positron emission tomography/computed tomography (PET/CT) studies. In a broad perspective, FDG-PET/CT has been used in staging, assessment of therapy response, identifying metastases and as a follow-up tool in a wide variety of pediatric malignancies. This review outlines the role of PET/CT in childhood malignancies other than hematological malignancies such as lymphoma and leukemia.

Is early response by (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography a predictor of long-term outcome in patients with metastatic colorectal cancer?

BACKGROUND

Identify in advance responder patients to chemotherapy in metastatic colorectal cancer (CRC) would allow prompt interruption of ineffective therapies in non-responder patients. Hence, predictive markers are sought in numerous trials to detect responder patients, including tumor shrinkage measured by imaging methods. Usually, Response Evaluation Criteria in Solid Tumors (RECIST) is used to evaluate tumor response in metastatic CRC, but these criteria are questionable with use of biological agents associated to chemotherapy. Our aim was correlate early metabolic response by (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography ((18)FDG-PET-CT) with long-term outcome in metastatic CRC in first-line therapy.

METHODS

We prospectively evaluated 36 patients with metastatic CRC in first-line treatment with 5-fluorouracil, leucovorin (folinic acid), oxaliplatin (FOLFOX) or 5-fluorouracil, leucovorin (folinic acid), irinotecan (FOLFIRI) associated with cetuximab or bevacizumab. (18)FDG-PET-CT was performed at baseline and after two cycles of chemotherapy. The early metabolic response [standardized uptake value (SUV)] was measured to identify responder and non-responder patients and correlated with overall survival (OS) and progression-free survival (PFS).

RESULTS

Median age was 58.5 years (range, 41-74 years). PFS was 15.5 months for responder and 13.3 months for non-responder (P=0.42), OS was 55.7 months for responder and not reached for non-responder. There was no correlation between delta-SUV and clinical and pathological variables analyzed. In the subgroup of patients who did not undergo resection of metastasis (45%), PFS was higher for responders (15.3×6.8 months, P=0.02).

CONCLUSIONS

According to our findings, early response by (18)FDG-PET-CT was not a predictor of long-term outcome for patients with metastatic CRC treated in the first-line chemotherapy with a monoclonal antibody.

The association of tumor-to-background ratios and SUVmax deviations related to point spread function and time-of-flight F18-FDG-PET/CT reconstruction in colorectal liver metastases

Background

The maximum standardized uptake value (SUVmax) is a common clinical parameter for quantification in F18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), but it is influenced by image reconstruction. The aim of this study was to analyze the association of SUVmax deviations related to point spread function (PSF) and time-of-flight (TOF) reconstruction with tumor-to-background ratios (TBR) in colorectal liver metastases (CRLM).

Methods

Fifteen patients (f, 6; m, 9; median age, 59 years; range, 32 to 72 years) with 28 liver metastases were included retrospectively. FDG-PET/CT imaging (median activity, 237 MBq; range, 231 to 252 MBq; median uptake, 61 min; range, 55 to 67 min) was performed on a Siemens Biograph mCT 64 followed by image reconstruction using 3D-ordered subset expectation maximization (3D-OSEM) or 3D-OSEM with PSF modeling - both with and without TOF information. Differences in SUVmax were analyzed using the Friedman test and Wilcoxon test for paired non-parametric data. The correlation of inter-method differences with the lesions’ TBR was studied using Spearman’s rank correlation coefficient (rho). Differences between lesions with low (<4.8) and high (>4.8) TBR were analyzed using the Mann-Whitney U test (TBR measured with 3D-OSEM; binarized by its median).

Results

There was a significant correlation of the lesions’ TBR with relative SUVmax differences related to PSF (PSF + TOF vs. 3D-OSEM + TOF, rho = 0.61; PSF vs. 3D-OSEM, rho = 0.52) or TOF (PSF + TOF vs. PSF, rho = −0.58; 3D-OSEM + TOF vs. 3D-OSEM, rho = −0.61). Accordingly, PSF algorithms only showed higher SUVmax than non-PSF algorithms in lesions with a high TBR (median differences at low/high TBR, +2.6%/+9.1% [PSF + TOF vs. 3D-OSEM + TOF]; +0.7%/+6.4% [PSF vs. 3D-OSEM]). TOF integration also led to higher SUVmax but mainly at low TBR (low/high TBR, +10.4%/+1.8% [PSF + TOF vs. PSF]; +8.6%/−0.1% [3D-OSEM + TOF vs. 3D-OSEM]).

Conclusions

Both PSF and TOF reconstruction resulted in a substantial alteration of SUVmax in CRLM. TOF provided the highest SUVmax increase in low-contrast lesions while - vice versa - PSF showed the most relevant increase in high-contrast lesions. Thus, one should be aware that quantitative analyses of lesions with varying TBR, e.g., in radiotherapy or follow-up studies, may be mainly affected by either PSF or TOF reconstruction, respectively.

The added value of PET/Ce-CT/DW-MRI fusion in assessment of hepatic focal lesions: PET/Ce-CT/DW-MRI fusion in hepatic focal lesion

INTRODUCTION

The liver hosts a variety of benign and malignant tumors. Accurate diagnosis can be challenging in certain cases, especially in patients with a history of malignancy or in those with underlying liver pathology, such as cirrhosis.

OBJECTIVES

To evaluate the added clinical value of multi-modality liver imaging utilizing PET/Ce-CT/DW-MRI for characterization of hepatic focal lesions (HFL) and compare it with each diagnostic modality when interpreted alone.

METHODS

The study included 35 patients with HFL. They were 7 females & 28 males; their age ranged from 41 to 78years, all patients underwent PET/Ce-CT and DW-MRI scans. Ce-CT, PET and DW-MR images were reviewed independently, and then combined PET/Ce-CT, PET/DW-MRI and PET/Ce-CT/DW-MRI scans were analyzed. The results were correlated with histopathology or clinical/imaging follow-up.

RESULTS

The 35 patients had 98 focal lesions. Fifty-three lesions were finally diagnosed as primary hepatocellular carcinoma, 18 lesions were metastases, 7 lesions were lymphoma and 20 lesions were benign. On a patient based analysis; the sensitivity, specificity, PPV, NPV and accuracy were 100%, 67%, 94%, 100% and 94% for PET/Ce-CT compared to 97%, 83%, 97%, 83% and 94 % for DW-MRI, respectively. Combined PET/Ce-CT/DW-MR scans raise those parameters up to 100%. On a lesion based analysis; the sensitivity, specificity, PPV, NPV and accuracy were 94%, 75%, 94%, 75%, 90% for PET/Ce-CT compared to 94%, 95%, 99%, 97% and 94 % for DW-MRI, respectively. All these parameters were 100 % with PET/Ce-CT/DW-MRI.

CONCLUSIONS

The addition of DW-MRI to PET/Ce-CT is valuable in the characterization of hepatic focal lesions.

Colorectal cancer with liver metastases: Neoadjuvant chemotherapy, surgical resection first or palliation alone?

Colorectal cancer (CRC) is one of the commonest cancers with 1.2 million new cases diagnosed each year in the world. It remains the fourth most common cause of cancer-related mortality in the world and accounts for > 600000 cancer-related deaths each year. There have been significant advances in treatment of metastatic CRC in last decade or so, due to availability of new active targeted agents and more aggressive approach towards the management of CRC, particularly with liver-only-metastases; however, these drugs work best when combined with conventional chemotherapy agents. Despite these advances, there is a lack of biomarkers to inform us about the accurate management of the patients with metastatic CRC. It is therefore imperative to carefully select the patients with comprehensive multi-disciplinary team input in order to optimise the management of these patients. In this review we will discuss various treatment options available in management of colorectal liver metastases with potential guidance on how and when to choose these options along with consideration on future directions in management of this disease.

[18F]Fluorodeoxyglucose PET for Interventional Oncology in Liver Malignancy

[(18)F]Fluorodeoxyglucose (FDG) PET is a functional imaging tool that provides metabolic information, which has the potential to detect a lesion before it becomes anatomically apparent. This ability constitutes a strong argument for using FDG-PET/computed tomography (CT) in the management of oncology patients. Many studies have investigated the accuracy of FDG-PET or FDG-PET/CT for these purposes, but with small sample sizes based on retrospective cohorts. This article provides an overview of the role of FDG-PET or FDG-PET/CT in patients with liver malignancies treated by means of surgical resection, ablative therapy, chemoembolization, radioembolization, and brachytherapy, all being liver-directed oncologic interventions.

Functional imaging of the bowel

Functional imaging techniques enable physiological information to be derived, which, combined with high-resolution anatomical imaging, has the potential to improve the management of patients with intestinal disease. Two of the common pathologies where imaging has a substantial role in depicting disease extent, in staging disease, and assessing therapeutic response and/or disease relapse are cancer and inflammatory bowel disease. In these scenarios, functional imaging may augment assessment of disease activity, therapeutic response/non-response, as well as disease relapse by indicating physiological changes as a result of tumor, inflammation, or fibrosis.

The influence of FDG PET-CT on the detection of extrahepatic disease in patients being considered for resection of colorectal liver metastasis

INTRODUCTION

The aim of this study was to evaluate the influence of flurodeoxyglucose positron emission tomography computed tomography (FDG PET-CT), as an adjunct to conventional CT staging, in the detection of extrahepatic disease in patients with potentially resectable colorectal liver metastasis.

METHODS

Overall, 133 consecutive patients with colorectal liver metastases staged with CT and PET-CT referred to the East Lancashire regional hepatobiliary multidisciplinary team over a two-year period were included in this study. Abnormal findings on PET-CT were correlated with follow-up imaging and/or histology. All imaging was reviewed by specialist hepatobiliary radiologists for the presence/absence of extrahepatic disease. The influence of the PET-CT findings was categorised for each patient in relation to operability and other significant findings.

RESULTS

PET-CT had a major impact on staging of extra hepatic disease in 20% of patients, in comparison with the initial CT. Six per cent of patients were upstaged from operable CT findings to inoperable findings on PET-CT because of the discovery of inoperable occult extrahepatic disease. Five per cent had operable local regional nodal disease detected on PET-CT. A further 3% had premalignant colorectal lesions detected on PET-CT. Six per cent of patients were downstaged from indeterminate or suspected inoperable CT findings to operable findings on PET-CT.

CONCLUSIONS

The use of PET-CT in this setting may prevent futile operations, guide the resection of local regional nodal disease and downstage a number of patients thought to have extrahepatic disease on conventional imaging. This study has shown similar results to other recent studies and supports the use of PET-CT as a necessary staging modality in patients with potentially resectable colorectal liver metastases.

Appropriate use of positron emission tomography with [(18)F]fluorodeoxyglucose for staging of oncology patients

Positron emission tomography (PET) was developed in the mid-1970, and its initial applications were for heart and brain imaging research. Nowadays, this technology is aimed mainly at staging or restaging tumours as it allows the assessment of biochemical processes that are either specific or associated with tumour biology. The full appreciation of PET potentials and limitations among general practitioners and internists cannot be considered achieved and the appropriate use of PET especially when coupled to X-ray computed tomography (CT) is still suboptimal. The majority of PET studies rely on the use of fluorodeoxyglucose labelled with fluorine-18 (FDG), which is a radiopharmaceutical specific for glucose transport and metabolism. PET with FDG is amenable for studying most type of tumours, including those of the head and neck, lung, oesophagus, colo-rectal, gastrointestinal stromal tumours, pancreas, some types of lymphomas and melanoma, whereas in some tumours, including those of the reproductive system, brain, breast and bones, there is a limited role for PET and there is no substantial role for FDG-PET for the bronchoalveolar, hepatocellular, urinary system, testicular, neuroendocrine, carcinoids and adrenal tumours, differentiated thyroid cancers, and several subtypes of malignant lymphoma. Thus, the limits of FDG have stimulated the use and development of other radiopharmaceuticals. These tracers represent the opportunity for expanding the use of PET to other areas in oncology in the near future.

Early PET/CT scan is more effective than RECIST in predicting outcome of patients with liver metastases from colorectal cancer treated with preoperative chemotherapy plus bevacizumab

Markers predictive of treatment effect might be useful to improve the treatment of patients with metastatic solid tumors. Particularly, early changes in tumor metabolism measured by PET/CT with (18)F-FDG could predict the efficacy of treatment better than standard dimensional Response Evaluation Criteria In Solid Tumors (RECIST) response.

METHODS

We performed PET/CT evaluation before and after 1 cycle of treatment in patients with resectable liver metastases from colorectal cancer, within a phase 2 trial of preoperative FOLFIRI plus bevacizumab. For each lesion, the maximum standardized uptake value (SUV) and the total lesion glycolysis (TLG) were determined. On the basis of previous studies, a ≤ -50% change from baseline was used as a threshold for significant metabolic response for maximum SUV and, exploratively, for TLG. Standard RECIST response was assessed with CT after 3 mo of treatment. Pathologic response was assessed in patients undergoing resection. The association between metabolic and CT/RECIST and pathologic response was tested with the McNemar test; the ability to predict progression-free survival (PFS) and overall survival (OS) was tested with the Log-rank test and a multivariable Cox model.

RESULTS

Thirty-three patients were analyzed. After treatment, there was a notable decrease of all the parameters measured by PET/CT. Early metabolic PET/CT response (either SUV- or TLG-based) had a stronger, independent and statistically significant predictive value for PFS and OS than both CT/RECIST and pathologic response at multivariate analysis, although with different degrees of statistical significance. The predictive value of CT/RECIST response was not significant at multivariate analysis.

CONCLUSION

PET/CT response was significantly predictive of long-term outcomes during preoperative treatment of patients with liver metastases from colorectal cancer, and its predictive ability was higher than that of CT/RECIST response after 3 mo of treatment. Such findings need to be confirmed by larger prospective trials.

Role of positron emission tomography-computed tomography in gastrointestinal malignancies

Positron emission tomography (PET) has proved itself to be valuable in the evaluation of patients with a wide array of gastrointestinal (GI) malignancies. Subsequent development of fusion imaging with PET and computed tomography (PET-CT) scanners has significantly advanced the capabilities of imaging by combining the functional data of the(18)F-labeled glucose analogue fluorodeoxyglucose (FDG) with the conventional anatomic data provided by CT. This article reviews the evolving role of FDG PET-CT imaging in the initial assessment and monitoring of GI tumors. Specific applications are discussed, and normal variants and benign findings frequently encountered during PET-CT of the GI tract are reviewed.

Rectal cancer staging: focus on the prognostic significance of the findings described by high-resolution magnetic resonance imaging

High-resolution (HR) magnetic resonance imaging (MRI) has become an indispensable tool for multidisciplinary teams (MDTs) addressing rectal cancer. It provides anatomic information for surgical planning and allows patients to be stratified into different groups according to the risk of local and distant recurrence. One of the objectives of the MDT is the preoperative identification of high-risk patients who will benefit from neoadjuvant treatment. For this reason, the correct evaluation of the circumferential resection margin (CRM), the depth of tumor spread beyond the muscularis propria, extramural vascular invasion and nodal status is of the utmost importance. Low rectal tumors represent a special challenge for the MDT, because decisions seek a balance between oncologic safety, in the pursuit of free resection margins, and the patient's quality of life, in order to preserve sphincter function. At present, the exchange of information between the different specialties involved in dealing with patients with rectal cancer can rank the contribution of colleagues, auditing their work and incorporating knowledge that will lead to a better understanding of the pathology. Thus, beyond the anatomic description of the images, the radiologist's role in the MDT makes it necessary to know the prognostic value of the findings that we describe, in terms of recurrence and survival, because these findings affect decision making and, therefore, the patients' life. In this review, the usefulness of HR MRI in the initial staging of rectal cancer and in the evaluation of neoadjuvant treatment, with a focus on the prognostic value of the findings, is described as well as the contribution of HR MRI in assessing patients with suspected or confirmed recurrence of rectal cancer.

Optimizing the role of FDG PET-CT for potentially operable metastatic colorectal cancer

Recent treatment advances now allow a realistic chance of cure in selected patients with metastatic colorectal carcinoma (CRC). Accurate pre-treatment staging is crucial to ensure appropriate management by identification of patients with more advanced disease who will not benefit from surgery. (18)Fluorine 2-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography (PET-CT) has a firmly established role in staging, restaging, and recurrence detection of a range of tumors. This article will review the role of PET-CT in patients with CRC with a particular emphasis on optimizing the technique in patients with potentially operable metastatic disease.

Positron emission tomography in malignancies of the liver, pancreas and biliary tract - indications and potential pitfalls

Abstract Malignancies of the hepato-pancreatico-biliary (HPB) system are relatively common and generally characterized by a dismal prognosis. Positron emission tomography (PET) is a functional imaging technique that has emerged as an important modality in oncological decision-making. The principal radiopharmaceutical in PET imaging is the glucose analog (18)F-fluorodeoxyglucose, which is able to detect altered glucose metabolism in malignant tissue. PET is typically used in conjunction with computed tomography (CT), and previous studies have supported several uses of PET/CT in HPB malignancies, including staging, differential diagnostics and monitoring of treatment response and progress of disease. A review of PET/CT in the context of HPB malignancies will be presented, including indications and potential pitfalls.