Radiation-induced esophagitis on FDG PET imaging

FDG PET/CT in a Case of Esophageal Extranodal NK/T-Cell Lymphoma, Nasal Type

ABSTRACT

Lymphoma involving the esophagus is rare. We describe FDG PET/CT findings in a case of extranodal NK/T-cell lymphoma, nasal type involving the larynx, hypopharynx, and cervical and upper thoracic esophagus. The esophageal tumor showed segmentally increased FDG uptake mimicking esophagitis. This case indicates that esophageal lymphoma should be included in the differential diagnosis of the hypermetabolic esophageal diseases.

FDG PET/CT in a Case of Diffuse Esophageal Adenocarcinoma

ABSTRACT

Esophageal cancer usually shows focal intense FDG uptake on FDG PET. Diffuse FDG uptake pattern of the esophageal cancer has been rarely reported. We describe FDG PET/CT findings in a case of esophageal adenocarcinoma showing diffusely intense FDG uptake mimicking esophagitis.

Clinical response assessment on DW-MRI compared with FDG-PET/CT after neoadjuvant chemoradiotherapy in patients with oesophageal cancer

PURPOSE

In about 30% of patients treated with neoadjuvant chemoradiotherapy (nCRT) followed by surgical resection for locally advanced oesophageal cancer no vital tumour is found in the resection specimen. Accurate clinical response assessment is critical if deferral from surgery is considered in complete responders. Our study aimed to compare the performance of MRI and of FDG-PET/CT for the detection of residual disease after nCRT.

METHODS

Patients with oesophageal cancer eligible for nCRT and oesophagectomy were prospectively included. All patients underwent FDG-PET/CT and MRI before and between 6 and 8 weeks after nCRT. Two radiologists scored the MRI scans, and two nuclear medicine physicians scored the FDG-PET/CT scans using a 5-point score for residual disease. Histopathology after oesophagectomy represented the reference standard. Sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were calculated for detection of residual tumour (ypT+), residual nodal disease (ypN+), and any residual disease (ypT+Nx/ypT0N+).

RESULTS

Seven out of 33 (21%) patients had a pathological complete response. The AUCs for individual readers to detect ypT+ were 0.71/0.70 on diffusion-weighted (DW)-MRI and 0.54/0.57 on FDG-PET/CT, and to detect ypN+ were 0.89/0.81 on DW-MRI and 0.75/0.71 on FDG-PET/CT. The AUCs/sensitivities/specificities for the individual readers to detect any residual disease were 0.74/92%/57% and 0.70/96%/43% on MRI; these were 0.49/69%/29% and 0.60/69%/43% on FDG-PET/CT, respectively.

CONCLUSION

MRI reached higher diagnostic accuracies than FDG-PET/CT for the detection of residual tumour in oesophageal cancer patients at 6 to 8 weeks after nCRT.

Differences in Normal Tissue Response in the Esophagus Between Proton and Photon Radiation Therapy for Non-Small Cell Lung Cancer Using In Vivo Imaging Biomarkers

PURPOSE

To determine whether there exists any significant difference in normal tissue toxicity between intensity modulated radiation therapy (IMRT) or proton therapy for the treatment of non-small cell lung cancer.

METHODS AND MATERIALS

A total of 134 study patients (n=49 treated with proton therapy, n=85 with IMRT) treated in a randomized trial had a previously validated esophageal toxicity imaging biomarker, esophageal expansion, quantified during radiation therapy, as well as esophagitis grade (Common Terminology Criteria for Adverse Events version 3.0), on a weekly basis during treatment. Differences between the 2 modalities were statically analyzed using the imaging biomarker metric value (Kruskal-Wallis analysis of variance), as well as the incidence and severity of esophagitis grade (χ² and Fisher exact tests, respectively). The dose-response of the imaging biomarker was also compared between modalities using esophageal equivalent uniform dose, as well as delivered dose to an isotropic esophageal subvolume.

RESULTS

No statistically significant difference in the distribution of esophagitis grade, the incidence of grade ≥3 esophagitis (15 and 11 patients treated with IMRT and proton therapy, respectively), or the esophageal expansion imaging biomarker between cohorts (P>.05) was found. The distribution of imaging biomarker metric values had similar distributions between treatment arms, despite a slightly higher dose volume in the proton arm (P>.05). Imaging biomarker dose-response was similar between modalities for dose quantified as esophageal equivalent uniform dose and delivered esophageal subvolume dose. Regardless of treatment modality, there was high variability in imaging biomarker response, as well as esophagitis grade, for similar esophageal doses between patients.

CONCLUSIONS

There was no significant difference in esophageal toxicity from either proton- or photon-based radiation therapy as quantified by esophagitis grade or the esophageal expansion imaging biomarker.

(18)F-Fluorodeoxyglucose Positron Emission Tomography Can Quantify and Predict Esophageal Injury During Radiation Therapy

PURPOSE

We sought to investigate the ability of mid-treatment (18)F-fluorodeoxyglucose positron emission tomography (PET) studies to objectively and spatially quantify esophageal injury in vivo from radiation therapy for non-small cell lung cancer.

METHODS AND MATERIALS

This retrospective study was approved by the local institutional review board, with written informed consent obtained before enrollment. We normalized (18)F-fluorodeoxyglucose PET uptake to each patient's low-irradiated region (<5 Gy) of the esophagus, as a radiation response measure. Spatially localized metrics of normalized uptake (normalized standard uptake value [nSUV]) were derived for 79 patients undergoing concurrent chemoradiation therapy for non-small cell lung cancer. We used nSUV metrics to classify esophagitis grade at the time of the PET study, as well as maximum severity by treatment completion, according to National Cancer Institute Common Terminology Criteria for Adverse Events, using multivariate least absolute shrinkage and selection operator (LASSO) logistic regression and repeated 3-fold cross validation (training, validation, and test folds). This 3-fold cross-validation LASSO model procedure was used to predict toxicity progression from 43 asymptomatic patients during the PET study. Dose-volume metrics were also tested in both the multivariate classification and the symptom progression prediction analyses. Classification performance was quantified with the area under the curve (AUC) from receiver operating characteristic analysis on the test set from the 3-fold analyses.

RESULTS

Statistical analysis showed increasing nSUV is related to esophagitis severity. Axial-averaged maximum nSUV for 1 esophageal slice and esophageal length with at least 40% of axial-averaged nSUV both had AUCs of 0.85 for classifying grade 2 or higher esophagitis at the time of the PET study and AUCs of 0.91 and 0.92, respectively, for maximum grade 2 or higher by treatment completion. Symptom progression was predicted with an AUC of 0.75. Dose metrics performed poorly at classifying esophagitis (AUC of 0.52, grade 2 or higher mid treatment) or predicting symptom progression (AUC of 0.67).

CONCLUSIONS

Normalized uptake can objectively, locally, and noninvasively quantify esophagitis during radiation therapy and predict eventual symptoms from asymptomatic patients. Normalized uptake may provide patient-specific dose-response information not discernible from dose.

The predictive value of 18F-FDG PET for pathological response of primary tumor in patients with esophageal cancer during or after neoadjuvant chemoradiotherapy: a meta-analysis

OBJECTIVE

We want to review the value of 18-fluoro-deoxy-glucose positron emission tomography for response prediction of primary tumor in patients with esophageal cancer during or after neoadjuvant chemoradiotherapy.

METHODS

Studies were searched in Pubmed, Embase and Cochrane Library with specific search strategy. The published articles were included according to the criteria established in advance. The included studies were divided into two groups according to the time of the repeat positron emission tomography: during (Group A) or after neoadjuvant chemoradiotherapy (Group B). The studies that performed the repeat positron emission tomography after neoadjuvant chemoradiotherapy were graded Quality Assessment of Diagnostic Accuracy Studies. The pooled sensitivity, specificity and diagnostic odds ratio were obtained for both groups on the basis of no-existing of threshold effect.

RESULTS

Fifteen studies were included in the present study. The threshold effect did not exist in both groups. The pooled sensitivity, specificity and diagnostic odds ratio were 85%, 59%, 6.82 with 95% confidence interval 76-91%, 48-69%, 2.25-20.72 in Group A. The equivalent values were 67%, 69%, 6.34 with 95% confidence interval 60-73%, 63-74%, 2.08-19.34 in Group B. The pooled sensitivity was 90% in four studies that enrolled patients with esophageal squamous cell carcinoma merely in Group B.

CONCLUSIONS

According to the present data, positron emission tomography should not be used routinely to guide treatment strategy in esophageal cancer patients. We speculated that positron emission tomography could be used as a tool to predict treatment response after neoadjuvant chemoradiotherapy in patients with esophageal squamous cell carcinoma.

Radiation-Induced Esophagitis Masquerading as Disease Progression in Case of Esophageal Carcinoma: A Diagnostic Dilemma Solved on Follow-up FDG PET/CT

Radiation esophagitis is one of the commonest complications of the radiotherapy involving esophagus. It is characterized by diffuse radiotracer uptake in the esophagus on ¹⁸F-FDG PET/CT. Thus, it can be often confused with the esophageal malignancy. We present the sequential ¹⁸F-FDG PET/CT images of a 45-year-old woman with locally advanced squamous cell carcinoma of the esophagus who developed radiation esophagitis after chemoradiotherapy. It was confused with the progression of the disease, and the dilemma was resolved by the follow-up PET/CT.

FDG PET/CT in eosinophilic esophagitis

A 37-year-old man presented with left upper abdominal pain for 13 months. Laboratory examinations showed elevated peripheral eosinophils. Chest CT showed thickened wall of the entire esophagus. FDG PET/CT was performed showing diffuse FDG uptake in the thickened esophageal wall. Esophageal endoscopy showed pale and edematous mucosa. Histologic examination of the esophageal biopsy specimens revealed marked eosinophil infiltration of the mucosa. The clinical and pathologic findings were consistent with eosinophilic esophagitis (EoE). This case indicates EoE should be included in the differential diagnosis of abnormal FDG accumulation in the esophageal wall along with malignant and nonmalignant conditions.

Postradiation changes in tissues: evaluation by imaging studies with emphasis on fluorodeoxyglucose-PET/computed tomography and correlation with histopathologic findings

Efforts have been made to minimize the damage to adjacent normal tissues during radiotherapy, primarily by shifting from the use of conventional radiotherapy to more advanced techniques. Reviewing the overall pattern on combined anatomic and functional imaging can enhance diagnostic accuracy. Several radiotracers can be used; [(18)F]fluorodeoxyglucose is the most common. Familiarity with the type and timing of previous radiation therapy, the spectrum of imaging findings after radiation injury, and the appropriate use of the different radiotracers can be crucial. This article summarizes postradiation histologic findings and multimodality imaging findings, with emphasis on PET/computed tomography.

Association of esophageal inflammation, obesity and gastroesophageal reflux disease: from FDG PET/CT perspective

OBJECTIVE

Gastroesophageal reflux disease (GERD) is associated with bothersome symptoms and neoplastic progression into Barrett's esophagus and esophageal adenocarcinoma. We aim to determine the correlation between GERD, esophageal inflammation and obesity with 18F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT).

METHODS

We studied 458 subjects who underwent a comprehensive health check-up, which included an upper gastrointestinal endoscopy, FDG PET/CT and complete anthropometric measures. GERD symptoms were evaluated with Reflux Disease Questionnaire. Endoscopically erosive esophagitis was scored using the Los Angeles classification system. Inflammatory activity, represented by standardized uptake values (SUVmax) of FDG at pre-determined locations of esophagus, stomach and duodenum, were compared. Association between erosive esophagitis, FDG activity and anthropometric evaluation, including body mass index (BMI), waist circumference, visceral and subcutaneous adipose tissue volumes were analyzed.

RESULTS

Subjects with erosive esophagitis (n = 178, 38.9%) had significantly higher SUVmax at middle esophagus (2.69±0.74 vs. 2.41±0.57, P<.001) and esophagogastric junction (3.10±0.89 vs. 2.38±0.57, P<.001), marginally higher at upper esophageal sphincter (2.29±0.42 vs. 2.21±0.48, P = .062), but not in stomach or duodenum. The severity of erosive esophagitis correlated with SUVmax and subjects with Barrett's esophagus had the highest SUVmax at middle esophagus and esophagogastric junction. Heartburn positively correlated with higher SUVmax at middle oesophagus (r = .262, P = .003). Using multivariate regression analyses, age (P = .027), total cholesterol level (P = .003), alcohol drinking (P = .03), subcutaneous adipose tissue (P<.001), BMI (P<.001) and waist circumference (P<.001) were independently associated with higher SUVmax at respective esophageal locations.

CONCLUSIONS

Esophageal inflammation demonstrated by FDG PET/CT correlates with endoscopic findings and symptomatology of GERD. Obesity markers, both visceral and general, are independent determinants of esophageal inflammation.

Timing and intensity of changes in FDG uptake with symptomatic esophagitis during radiotherapy or chemo-radiotherapy

Purpose

To study whether esophageal FDG activity changes by time of mid-course of fractionated radiotherapy (RT), and whether these changes are associated with radiation esophagitis in patients with non-small cell lung cancer (NSCLC).

Methods

Fifty patients with stage I-III NSCLC were enrolled prospectively and, all received ≥60 Gy RT. FDG-PET/CT scans were acquired prior to, and during-RT after delivery of 45 Gy. Normalized standardized uptake values (NSUV), defined by the esophageal maximum SUV relative to intravascular background level in the aortic arch, were sampled in the esophagus at the level of the primary tumor, sternal notch, aortic arch, carina, and gastro-esophageal junction. Symptomatic radiation esophagitis was defined as an event.

Results

Compared to baseline, esophageal NSUV increased significantly during-RT at the level of the primary tumor (1.09 ± 0.05 vs.1.28 ± 0.06, p = 0.001), but did not change at other levels in the esophagus. 16 patients had radiation esophagitis events and these patients had significantly higher during-RT to baseline NSUV ratios than those without esophagitis (1.46 ± 0.12, 95% CI 1.20-1.71; vs. 1.11 ± 0.05, 95% CI 1.01-1.21, p = 0.002). Maximum esophageal dose (p = 0.029), concurrent chemotherapy (p = 0.022) and esophageal FDG PET NSUV ratio (during-RT to baseline, p = 0.007), were independent factors associated with esophagitis and area under curves (AUC) were 0.76, 0.70 and 0.78, respectively. Combining esophageal maximum dose and FDG PET NSUV Ratio at the tumor level increased AUC to 0.85 (p = 0.016).

Conclusion

FDG uptake increased in esophagus during-RT and this increase may predict radiation esphagitis during later course of treatment.

Relating acute esophagitis to radiotherapy dose using FDG-PET in concurrent chemo-radiotherapy for locally advanced non-small cell lung cancer

PURPOSE

To correlate radiotherapy (RT) dose to acute esophagitis (AE) by means of FDG-PET scans acquired after concurrent chemo-radiotherapy (cCRT) for locally advanced non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

Patients treated with 24 × 2.75 Gy were selected on presence of a post-RT PET (PET(post)) scan acquired within 3 months after cCRT. The value of PET(post) in relation to AE was evaluated by comparing the mean esophageal SUV of the highest 50% (mathematical left angle bracket SUV(50%) mathematical right angle bracket) between gr < 2 and gr ≥ 2AE. The local dose on the esophagus wall was correlated to the SUV and modeled using a power-law fit. The Lyman-Kutcher-Burman (LKB) model was used to predict gr ≥ 2AE. The local dose-response relation was used in the LKB model to calculate the EUD. Resulting prediction accuracy was compared to D(mean), V(35), V(55) and V(60).

RESULTS

Eighty-two patients were included (gr < 2 = 25, gr ≥ 2=57). The mathematical left angle bracket SUV(50%) mathematical right angle bracket ≥ was significantly higher for gr ≥ 2AE (2.2 vs. 2.6, p < 0.01). The LKB parameters (95% CI) were n = 0.130 (0.120-0.141), m = 0.25 (0.13-0.85) and TD(50) = 50.4 Gy (37.5-55.4), which resulted in improved predictability of AE compared to other predictors.

CONCLUSION

Esophageal uptake of FDG post-cCRT reflects AE severity. Predictability of grade ≥ 2AE was improved by using the local dose-SUV response model, with narrow confidence intervals for the optimized LKB parameters.

Role of (18F) 2-fluoro-2-deoxyglucose positron emission tomography in upper gastrointestinal malignancies

The role of whole-body FDG [(¹⁸F) 2-fluoro-2-deoxyglucose] positron emission tomography (PET) scanning as an imaging modality in the management of patients with malignancy has evolved enormously over the past two decades. FDG-PET has demonstrated significant efficacy in the staging, prognostication and detection of occult metastatic disease in malignancies of the gastrointestinal tract, in addition to assessment of the response to cytotoxic chemotherapy in a more timely manner than has traditionally been possible by more conventional imaging tools. The sensitivity and specificity of FDG-PET for the detection and staging of malignancy depend not only on the site and size of the primary tumor and metastases, but also on histological cell type, reflecting underlying disparities in glucose metabolism. The metabolic response to neo-adjuvant chemotherapy or to chemo-radiotherapy in cancers of the gastro-esophageal junction or stomach has been demonstrated in several prospective studies to correlate significantly with both the histological tumor response to treatment and with consequent improvements in overall survival. This may offer a future paradigm of personalized treatment based on the PET response to chemotherapy. FDG-PET has been less successful in efforts to screen for and detect recurrent upper gastrointestinal malignancies, and in the detection of low volume metastatic peritoneal disease. Efforts to improve the accuracy of PET include the use of novel radiotracers such as (¹⁸F) FLT (3-deoxy-3-fluorothymidine) or ¹¹C-choline, or fusion PET-CT with concurrent high-resolution computed tomography. This review focuses on the role of FDG-PET scanning in staging and response assessment in malignancies of the upper gastrointestinal tract, specifically gastric, esophageal and pancreas carcinoma.

Metabolic response evaluation by PET during neoadjuvant treatment for adenocarcinoma of the esophagus and esophagogastric junction

Following several randomized trials, neoadjuvant therapy in adenocarcinoma of esophagus and the esophagogastric junction can be seen as an international standard. However, in a large proportion of patients the objective response achieved is unsatisfactory. These patients do not benefit from neoadjuvant therapy, but do suffer from toxic side effects; sometimes progressive and appropriate surgical therapy is delayed. For this reason, a diagnostic test that can accurately assess tumor response to neoadjuvant therapy might be of crucial importance. Response evaluation using CT scan, endoluminal ultrasound, or rebiopsy is not reliable. In recent times, response evaluation using 18FGD PET after and during neoadjuvant treatment is in the focus of clinical and scientific interest. Most studies have evaluated the diagnostic modalities for response to neoadjuvant treatment after completion of the treatment. Following the published data so far, FDG-PET seems to be less accurate after and during chemoradiation than after chemotherapy alone. The data of early response evaluation (14 days after the onset of chemotherapy) are very much encouraging; however, they have to be evaluated in an international randomized trial. Standardization of PET technology as well as defining the thresholds used for the estimation of early response is mandatory. So far, FDG-PET does not change treatment in esophageal and gastric cancer.

Physiology and pathophysiology of incidental findings detected on FDG-PET scintigraphy

A routine feature of positron emission tomography/computed tomography (PET/CT) imaging is whole-body acquisition that results in many unexpected findings identified outside of the primary region of abnormality. Furthermore, (18)F-fluorodeoxyglucose (FDG) is a marker of glycolysis and does not specifically accumulate in malignancy. Understanding the physiology and pathophysiology of normal FDG distribution and common incidental findings is therefore essential to the physician interpreting whole-body FDG-PET/CT studies. Whereas many incidental findings are benign and of limited clinical significance, others represent uncommon manifestations of the primary malignancy, second malignancies, or various clinically significant pathologic processes. Patients with a single malignancy are at greater risk of developing synchronous or metachronous second malignancies, possibly related to exposure to shared carcinogenic agents or presence of prooncogenic mutations. The decision of how to pursue an intervention on the basis of an incidental finding is generally left to clinical judgment.

Evidence-based radiation oncology: oesophagus

Oesophageal cancer remains to be a therapeutic and diagnostic challenge in multidisciplinary oncology. Radiotherapy is a crucial component of most curative and palliative approaches for oesophageal cancer. Aim of this educational review is to summarize the available evidence and to define the role of radiation-based treatment options for oesophageal cancer.

Impact of fluorodeoxyglucose PET on the management of esophageal cancer

Esophageal cancer is the third most common malignancy of the alimentary tract. The incidence of esophageal cancer has steadily increased over the past three decades. Almost all therapeutic modalities for esophageal cancer are associated with a considerable mortality and morbidity. Consequently, there has been growing concern regarding effective management of esophageal cancer. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) is playing an increasing role in the management of esophageal cancer, offering potential advantages in the accuracy of disease assessment at a number of decision points in the management pathway. This review evaluates the critical role of FDG-PET in (i) diagnosis, (ii) preoperative staging, (iii) monitoring of response to neoadjuvant therapy, (iv) assessment of recurrence and (v) prediction of prognosis of esophageal cancer. We have also compared diagnostic performance of FDG-PET and other current technologies such as computed tomography scan and endoscopic ultrasonography based on available evidence.

The use of dynamic positron emission tomography imaging for evaluating the carcinogenic progression of intestinal metaplasia to esophageal adenocarcinoma

BACKGROUND

In this study, we investigate the use of PET scanning in the carcinogenic progression of reflux esophagitis to Barrett's esophagus to high grade dysplasia to esophageal adenocarcinoma, and correlate the uptake levels of 18F-FDG related to histological changes, and the rates of proliferation and apoptosis.

METHODS

An established esophagoduodenal anastomsis rat model in conjunction with micro-PET scanning at 1 week, 1 month, 3 month, and 6 month after procedure was performed.

RESULTS

Increased uptake levels of 18F-FDG were observed in the esophagi after EDA procedure. The higher level of 18F-FDG uptake within esophageal epithelium was identified in intestinal metaplastic transformation and esophagoduodenal adenocarcinoma by histological examination.

CONCLUSIONS

Dynamic PET scanning represents a powerful tool in analyzing morphological carcinogenic transformation non-invasively in the esophagus. 18F- FDG accumulation was a sensitive marker in reflux esophageal injury carcinogenic progression from intestinal metaplasia to EAC.

PET/CT in oncology: for which tumours is it the reference standard?

Positron emission tomography (PET)/computed tomography (CT) has a growing role in the imaging of many cancers. As our experience has grown over the past number of years so has our understanding for which cancers it is particularly useful. The value of PET/CT at each stage of the cancer journey is different for each cancer. This review attempts to tease out the role of PET/CT in the common cancers with particular emphasis on where it is the imaging investigation of choice.

FDG-PET/CT tumor segmentation-derived indices of metabolic activity to assess response to neoadjuvant therapy and progression-free survival in esophageal cancer: correlation with histopathology results

PURPOSE

To evaluate the diagnostic and prognostic abilities of PET tumor segmentation-derived indices of metabolic activity for the assessment of response to neoadjuvant chemoradiotherapy and progression-free survival in patients with esophageal cancer.

METHODS

Twenty-five patients with histologically confirmed esophageal cancer were retrospectively evaluated. The patients underwent PET-CT imaging before and after completion of neoadjuvant therapy. Images were evaluated visually and quantitatively with a three-dimensional threshold-based region-growing program, which calculates SUVm, SUVa of the entire tumor, metabolic tumor length (Lm) and volume (Vm) before and after therapy (SUVm1, SUVm2, SUVa1, SUVa2, Lm1, Lm2, Vm1, and Vm2, respectively). Percentage changes in these metabolic variables before and after therapy were also calculated (%SUVm, %SUVa, %Lm, %Vm, respectively).

RESULTS

SUVm1 (P = 0.018), SUVa1 (P = 0.019), Lm1 (P = 0.016), and Vm1 (P = 0.016) correlated with T-status. Advanced stage tumors (T3 + T4) had significantly higher glucose metabolism, metabolic length, and volume. Moreover, Lm1 >47.4 mm and Vm1 >29 cm3 were the best predictors of the level of tumor invasiveness. SUVm1 >12.7 and SUVa1 >5.9 could differentiate patients with positive lymph nodes from those without at presentation. %SUVa >32.3% and the SUVa1 >5.5 proved to be reliable predictors of pathologic response. SUVa2 >3.55 and SUVm2 >4.35 were the best predictors of disease progression during follow-up, with the latter having the best prognostic value.

CONCLUSIONS

This study showed that FDG-PET tumor segmentation-derived indices of metabolic activity play a definite role in the evaluation of response to neoadjuvant chemoradiotherapy and progression-free survival in patients with esophageal cancer.

The role of integrated computed tomography positron-emission tomography in esophageal cancer: staging and assessment of therapeutic response

Computed tomography (CT) and endoscopy/endoscopic ultrasonography are usually performed to initially stage patients with esophageal cancer, to determine primary tumor response, and to detect nodal and distant metastases after preoperative therapy. Positron-emission tomography (PET) with [18F]-fluoro-2-deoxy-D-glucose and integrated CT-PET are useful in the initial staging of patients with esophageal cancer as well as in the prediction of pathologic response, disease-free interval, and overall survival after preoperative therapy. Importantly, integrated CT-PET imaging decreases the number of futile attempts at surgical resection, mainly because of the detection of occult distant metastases. The following sections review the use of integrated CT-PET imaging in determining the T, N, and M descriptors of the American Joint Commission on Cancer's 2002 guidelines for pathologic and clinical staging at initial diagnosis and after chemoradiation therapy in those patients being considered for surgical resection.

PET/CT: form and function

Functional imaging with positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of malignant disease, image-guided therapy planning, and treatment monitoring. PET with the labeled glucose analogue fluorine 18 fluorodeoxyglucose (FDG) is a relatively recent addition to the medical technology for imaging of cancer, and FDG PET complements the more conventional anatomic imaging modalities of computed tomography (CT) and magnetic resonance imaging. CT is complementary in the sense that it provides accurate localization of organs and lesions, while PET maps both normal and abnormal tissue function. When combined, the two modalities can help both identify and localize functional abnormalities. Attempts to align CT and PET data sets with fusion software are generally successful in the brain; other areas of the body is more challenging, owing to the increased number of degrees of freedom between the two data sets. These challenges have recently been addressed by the introduction of the combined PET/CT scanner, a hardware-oriented approach to image fusion. With such a device, accurately registered anatomic and functional images can be acquired for each patient in a single scanning session. Currently, over 800 combined PET/CT scanners are installed in medical institutions worldwide, many of them for the diagnosis and staging of malignant disease and increasingly for monitoring of the response to therapy. This review will describe some of the most recent technologic developments in PET/CT instrumentation and the clinical indications for which combined PET/CT has been shown to be more useful than PET and CT performed separately.

Bowel hot spots at PET-CT

Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) has been shown to be sensitive in the detection of many bowel malignancies, but its specificity is lower because of various physiologic and pathologic patterns of bowel FDG uptake. PET-computed tomography (CT) can be useful in localizing and characterizing foci of increased FDG uptake within the bowel. As the use of PET-CT in the staging and monitoring of oncologic disease continues to expand, familiarity with these patterns of bowel FDG uptake is essential and can help determine the need for and the relative urgency of further testing. Although a variety of imaging protocols are used for PET-CT, the use of negative oral contrast agent allows improved bowel distention while eliminating potential artifacts caused by high-density oral contrast agents. In addition, correlation with the CT portion of the combined PET-CT examination can sometimes help identify the cause of focal or segmental bowel uptake. The radiologist should be aware of potential pitfalls in the evaluation of FDG-avid foci within the abdomen, including bowel motility and low-attenuation lesions mimicking bowel. Nevertheless, even though the precise role of combined PET-CT for bowel assessment has yet to be determined, the application of sound basic principles of image interpretation will help ensure the accurate interpretation of bowel findings seen with this combined modality.

Esophageal Cancer: The Role of Integrated CT-PET in Initial Staging and Response Assessment After Preoperative Therapy

Esophageal cancer, an uncommon neoplasm, has been increasing in incidence over the past few decades. Optimal management of patients is determined by the stage of disease at presentation, patient performance status, and location of the primary cancer. Recently, there has been increasing use of multimodality therapy in suitable candidates that employs preoperative chemotherapy and/or radiation followed by surgical resection. This evolving treatment strategy together with the substantial morbidity and mortality associated with esophagectomy makes appropriate patient selection critical. Computed tomography (CT) and endoscopy/endoscopic ultrasonography are usually carried out to initially stage patients with esophageal cancer, to determine primary tumor response, and to detect nodal and distant metastases after preoperative therapy. Positron emission tomography (PET) with [18F]-fluoro-2-deoxy-D-glucose and integrated CT-PET are useful in the initial staging of patients with esophageal cancer and in the prediction of pathologic response, disease-free interval, and overall survival after preoperative therapy. Importantly, integrated CT-PET imaging decreases the number of futile attempts at surgical resection, mainly because of the detection of occult distant metastases. The following sections review the use of integrated CT-PET imaging in determining the T, N, and M descriptors of the American Joint Commission on Cancer's 2002 guidelines for pathologic and clinical staging at initial diagnosis and after chemoradiation therapy in those patients being considered for surgical resection.

Intense esophageal FDG activity caused by Candida infection obscured the concurrent primary esophageal cancer on PET imaging

Esophageal cancer frequently causes a focal intense FDG uptake on positron emission tomography (PET) imaging while esophagitis often results in a mild to moderate degree of FDG activity in a diffuse pattern. However, detection of an esophageal cancer can become difficult in the presence of a diffuse esophageal activity because of esophagitis. We present such case in which esophageal cancer superimposed by Candidal esophagitis is difficult to recognize on FDG PET images.

Utility of PET, CT, and EUS to identify pathologic responders in esophageal cancer

BACKGROUND

This study evaluates the utility of positron emission tomography (PET), endoscopic ultrasonography (EUS), and computed tomographic (CT) scans to predict pathologic response and survival following preoperative chemoradiation (CRT) in esophageal cancer.

METHODS

One hundred three sequential patients with locoregionally advanced esophageal cancer, who were treated with CRT and esophageal resection between May 2001 and November 2003 at the University of Texas M.D. Anderson Cancer Center, were retrospectively reviewed. PET, EUS, and CT were performed before (pre) or after (post) CRT and before surgical resection. PET standardized uptake value (SUV) was defined as maximal uptake in primary tumor.

RESULTS

Most patients were male (91 [88%]) with adenocarcinoma (90 [87%]). Pretreatment clinical stages were: IIA (42 [41%]), IIB (5 [5%]), III (50 [49%]), and IVA (6 [6%]). At the time of surgery, 58 patients (56%) had a pathologic response to CRT (< or =10% viable cells). Post-CRT measurements that correlated with pathologic response were: CT esophageal wall thickness (13.3 vs 15.3 mm, p = 0.04), EUS mass size (0.7 vs 1.7 cm, p = 0.01) and PET SUV (3.1 vs 5.8, p = 0.01). Post-CRT PET SUV equal to or greater than 4 had the highest accuracy for pathologic response (76%). Univariate and multivariate Cox regression analysis demonstrated that a post-CRT PET SUV equal to or greater than 4 was an independent predictor of survival (HR, 3.5, p = 0.04).

CONCLUSIONS

The FDG-PET SUV is the most accurate noninvasive test to predict long-term survival after preoperative CRT and before surgical resection. Post-CRT FDG-PET cannot, however, rule out residual microscopic disease so esophagectomy should remain a therapeutic option even if the post-CRT imaging modalities are normal.

Applications of fluorodeoxyglucose-PET imaging in the detection of infection and inflammation and other benign disorders

FDG-PET has great potential in the evaluation of a variety of inflammatory and infectious disorders and possibly other benign disorders. FDG-PET is very helpful in the evaluation of chronic osteomyelitis, sarcoidosis, FUO, and differentiating toxoplasmosis from lymphoma in the central nervous system in HIV-positive patients. The assessment of efficacy of FDG-PET in the evaluation of arthroplasty-associated infection, large-vessel vasculitis, and other inflammatory and infectious disorders is ongoing but seems quite promising at this time.