18 F-Fluorodeoxyglucose Uptake in Bilateral Diaphragmatic Crura: A Relatively Uncommon Benign Variant Noted in a Treated Case of Extraosseous Paraspinal Ewing's Sarcoma

A toddler was diagnosed with extraosseous Ewing's sarcoma, primary large epidural paraspinal soft tissue in the lumbar region encasing the cord and neural foramen from D12-L1 to L4-L5. After eight cycles of induction chemotherapy with vincristine, doxorubicin, and cyclophosphamide alternating with etoposide and ifosfamide, 18 F-FDG positron emission tomography/computed tomography ( 18 F-FDG-PET/CT) scan confirmed no active disease. Later external beam radiotherapy (EBRT) at D10-L5 was completed. At 3 months follow-up, 18 F-FDG-PET/CT reconfirmed no residual/active disease; however, a new incidental finding of diffuse benign bilateral diaphragmatic 18 F-FDG uptake was noted in the clinically asymptomatic patient, which remained unexplained.

False Liver Metastasis by Positron Emission Tomography/Computed Tomography Scan after Chemoradiotherapy for Esophageal Cancer-Potential Overstaged Pitfalls of Treatment

In patients with esophageal cancer undergoing neoadjuvant chemoradiotherapy (nCRT), subsequent restaging with F-18-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET-CT) can reveal the presence of interval metastases, such as liver metastases, in approximately 10% of cases. Nevertheless, it is not uncommon in clinical practice to observe focal FDG uptake in the liver that is not associated with liver metastases but rather with radiation-induced liver injury (RILI), which can result in the overstaging of the disease. Liver radiation damage is also a concern during distal esophageal cancer radiotherapy due to its proximity to the left liver lobe, typically included in the radiation field. Post-CRT, if FDG activity appears in the left or caudate liver lobes, a thorough investigation is needed to confirm or rule out distant metastases. The increased FDG uptake in liver lobes post-CRT often presents a diagnostic dilemma. Distinguishing between radiation-induced liver disease and metastasis is vital for appropriate patient management, necessitating a combination of imaging techniques and an understanding of the factors influencing the radiation response. Diagnosis involves identifying new foci of hepatic FDG avidity on PET/CT scans. Geographic regions of hypoattenuation on CT and well-demarcated regions with specific enhancement patterns on contrast-enhanced CT scans and MRI are characteristic of radiation-induced liver disease (RILD). Lack of mass effect on all three modalities (CT, MRI, PET) indicates RILD. Resolution of abnormalities on subsequent examinations also helps in diagnosing RILD. Moreover, it can also help to rule out occult metastases, thereby excluding those patients from further surgery who will not benefit from esophagectomy with curative intent.

Value of subspecialist second opinion reads of 18 F-FDG PET-CT examinations for patients with breast cancer

OBJECTIVES

Determine if subspecialist second opinion review alters reporting of malignancy on 18 F-FDG PET/CT for patients with breast cancer.

METHODS

This IRB-approved retrospective study compared 248 s opinion reads of 18 F-FDG PET/CT exams performed for patients with breast cancer against the original outside institution reports. Subspecialist reviews documented if malignant findings on the outside report were believed to be malignant and noted additional malignant findings not described on the outside report. Reference standard for malignancy or benignity was determined by pathology or follow-up imaging.

RESULTS

Of 248 cases, 27 (11%) had discrepancies in the presence or absence of extra-axillary nodal or distant metastases. Of these 27, 14 (52%) had biopsy or imaging follow-up as a reference standard for malignancy/benignity. In cases with reference standard proof, the subspecialist second opinion review was correct in 13/14 (93%) of cases. This included eleven cases that the original report called malignant, but the subspecialist review called benign and subsequently proven to be benign; as well as two metastases called on subspecialist review, but not on the original report, and subsequently biopsy proven to be metastases. In one case, the second opinion read called a suspicious lesion that was biopsy proven to be benign.

CONCLUSION

Subspecialist review improves the accuracy of diagnosis for the presence or absence of malignancy on FDG PET/CT examinations in patients with breast cancer. This demonstrates the value of performing second opinion reads of 18 F-FDG PET/CT studies in patients with breast cancer, particularly by subspecialist second opinion review reducing false positive reads.

Radiotherapy modification based on artificial intelligence and radiomics applied to (18F)-fluorodeoxyglucose positron emission tomography/computed tomography

Over the last decades, the refinement of radiation therapy techniques has been associated with an increasing interest for individualized radiation therapy with the aim of increasing or maintaining tumor control and reducing radiation toxicity. Developments in artificial intelligence (AI), particularly machine learning and deep learning, in imaging sciences, including nuclear medecine, have led to significant enthusiasm for the concept of "rapid learning health system". AI combined with radiomics applied to (18F)-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]-FDG PET/CT) offers a unique opportunity for the development of predictive models that can help stratify each patient's risk and guide treatment decisions for optimal outcomes and quality of life of patients treated with radiation therapy. Here we present an overview of the current contribution of AI and radiomics-based machine learning models applied to (18F)-FDG PET/CT in the management of cancer treated by radiation therapy.

Breast Cancer and Physiologic Avidity From Breast Feeding on FDG PET/CT

ABSTRACT

A 35-year-old woman presented with breast cancer diagnosed during pregnancy. Eleven days after delivery, the patient underwent FDG PET/CT for systemic staging. Avidity was seen diffusely in both breasts, with a more avid focus at the site of a biopsy clip in the right breast. There were no lymph nodes or distant metastases. The patient was actively breast feeding, explaining the diffuse breast avidity. This case demonstrates both malignant and benign FDG avidity in the breasts at the same time, with a focal FDG-avid right breast malignancy identified among bilateral breast parenchyma with elevated physiologic FDG-avid secondary to breast feeding.

Complete Femoral Osteonecrosis in the Setting of Myelodysplastic Syndrome

ABSTRACT

A 76-year-old man was diagnosed with a hematological neoplasm combining myelodysplastic and myeloproliferative characteristics back in July 2021. Five months after the diagnosis, his condition got more severe when the blasts rose up to 14%, so he was started on hypomethylating agent-based therapy. A few weeks later, the patient was hospitalized after developing fever and a pain in the right thigh. To exclude any source of occult infection, an 18 F-FDG PET/CT was performed. FDG PET/CT showed a complete lack of metabolism in the right femur. An MRI and a biopsy confirmed the suspected diagnosis of osteonecrosis.

Successful treatment of extensive-stage small cell lung cancer with concurrent pleural and pericardial effusions: Case report

It is unclear whether pleural/pericardial drainage and pleurodesis/pericardiodesis should be performed before or after initiating chemotherapy in patients with chemotherapy-sensitive small-cell lung cancer. A 76-year-old woman presented to the emergency department with progressive dyspnea on exertion for a week. Chest computed tomography showed a mass shadow anterior to the left upper lobe, bilateral pleural effusions, and a circumferential pericardial effusion surrounding the heart. We diagnosed extensive-stage small-cell lung cancer based on the clinical course and pathological findings. We first performed pleurodesis and pericardial drainage and successfully initiated immune checkpoint inhibitor combined chemotherapy, with improved performance status. This case highlights the importance of aggressive drainage and pleurodesis/pericardiodesis, and suggests that drainage and pleurodesis/pericardiodesis should be considered before systemic chemotherapy in patients with concurrent pericardial or pleural effusions, even in patients with small-cell lung cancer that is sensitive to chemotherapy.

PET-CT in the Evaluation of Neoadjuvant/Adjuvant Treatment Response of Soft-tissue Sarcomas: A Comprehensive Review of the Literature

➢

In soft-tissue sarcomas (STSs), the use of positron emission tomography-computed tomography (PET-CT) through a standardized uptake value reduction rate correlates well with histopathological response to neoadjuvant treatment and survival.

➢

PET-CT has shown a better sensitivity to diagnose systemic involvement compared with magnetic resonance imaging and CT; therefore, it has an important role in detecting recurrent systemic disease. However, delaying the use of PET-CT scan, to differentiate tumor recurrence from benign fluorodeoxyglucose uptake changes after surgical treatment and radiotherapy, is essential.

➢

PET-CT limitations such as difficult differentiation between benign inflammatory and malignant processes, inefficient discrimination between benign soft-tissue tumors and STSs, and low sensitivity when evaluating small pulmonary metastases must be of special consideration.

The potential of biology-guided radiation therapy in thoracic cancer: A preliminary treatment planning study

Purpose

We investigated the feasibility of biology-guided radiotherapy (BgRT), a technique that utilizes real-time positron emission imaging to minimize tumor motion uncertainties, to spare nearby organs at risk.

Methods

Volumetric modulated arc therapy (VMAT), intensity-modulated proton (IMPT) therapy, and BgRT plans were created for a paratracheal node recurrence (case 1; 60 Gy in 10 fractions) and a primary peripheral left upper lobe adenocarcinoma (case 2; 50 Gy in four fractions).

Results

For case 1, BgRT produced lower bronchus V40 values compared to VMAT and IMPT. For case 2, total lung V20 was lower in the BgRT case compared to VMAT and IMPT.

Conclusions

BgRT has the potential to reduce the radiation dose to proximal critical structures but requires further detailed investigation.

PET/MR imaging in gynecologic cancer: tips for differentiating normal gynecologic anatomy and benign pathology versus cancer

Positron emission tomography/magnetic resonance imaging (PET/MR) is used in the pre-treatment and surveillance settings to evaluate women with gynecologic malignancies, including uterine, cervical, vaginal and vulvar cancers. PET/MR combines the excellent spatial and contrast resolution of MR imaging for gynecologic tissues, with the functional metabolic information of PET, to aid in a more accurate assessment of local disease extent and distant metastatic disease. In this review, the optimal protocol and utility of whole-body PET/MR imaging in patients with gynecologic malignancies will be discussed, with an emphasis on the advantages of PET/MR over PET/CT and how to differentiate normal or benign gynecologic tissues from cancer in the pelvis.

[18F]FDG-PET/CT radiomics and artificial intelligence in lung cancer: Technical aspects and potential clinical applications

Lung cancer is the second most common cancer and the leading cause of cancer-related death worldwide. Molecular imaging using [¹⁸F]fluorodeoxyglucose Positron Emission Tomography and/or Computed Tomography ([¹⁸F]FDG-PET/CT) plays an essential role in the diagnosis, evaluation of response to treatment, and prediction of outcomes. The images are evaluated using qualitative and conventional quantitative indices. However, there is far more information embedded in the images, which can be extracted by sophisticated algorithms. Recently, the concept of uncovering and analyzing the invisible data extracted from medical images, called radiomics, is gaining more attention. Currently, [¹⁸F]FDG-PET/CT radiomics is growingly evaluated in lung cancer to discover if it enhances the diagnostic performance or implication of [¹⁸F]FDG-PET/CT in the management of lung cancer. In this review, we provide a short overview of the technical aspects, as they are discussed in different articles of this special issue. We mainly focus on the diagnostic performance of the [¹⁸F]FDG-PET/CT-based radiomics and the role of artificial intelligence in non-small cell lung cancer, impacting the early detection, staging, prediction of tumor subtypes, biomarkers, and patient's outcomes.

[18F]FDG-PET Evaluation of Spinal Pathology in Patients in Oncology: Pearls and Pitfalls for the Neuroradiologist

[¹⁸F]FDG-PET is a widely used technique for specific evaluation of disease and treatment response in oncology. However, the principles behind [¹⁸F]FDG-PET imaging allow a wide-ranging array of benign and malignant pathologies to be identified on both initial and routine surveillance imaging. This is important for clinicians and radiologists, alike, in that effective and accurate evaluation of malignancy and metastatic disease, specifically involving the spine and central nervous system, is crucial. In this article, we review the normal and posttherapy appearance of the spine on [¹⁸F]FDG-PET, the various types and patterns of metastatic disease that involve the spine and spinal cord, and, finally, important spinal pathologies that may mimic malignancy on [¹⁸F]FDG-PET.

PET/CT Variants and Pitfalls in Gynecological Cancers

The role of hybrid imaging with 2-[18F] flourodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) is continuously evolving and now considered standard practice in evaluation of disease stage, treatment response, recurrent disease and follow-up for numerous primary malignancies. In gynecological malignancies FDG PET/CT plays an important role, not only in the assessment of disease in the pre-and post-therapy setting, but also in radiation therapy (RT) planning by defining the metabolically active gross tumor volume (GTV. The glucose analogue radiotracer, FDG, is by far the most utilized radiotracer in PET/CT and is typically seen with high uptake in malignant cells. The radiotracer FDG has a high sensitivity but low specificity for malignancy, as benign processes with an inflammatory response for example infection, are also FDG-avid. In the evaluation of the female pelvic region an awareness of potential confounding factors in the interpretation of FDG is essential as variations of FDG uptake occur in accordance with the menstrual cycle and the menopausal state. Incidental imaging findings in the female genital can pose differential diagnostic challenges as false-positive and false-negative findings in benign and malignant processes are not uncommon. Gynecological malignancies continue to pose major public health problems with cervical cancer as the fourth most common cancer in women ranking after breast cancer, colorectal cancer and lung cancer. Familiarity with frequently encountered benign and malignant variants and pitfalls in FDG PET/CT in the female pelvic region can aid the reader in differential diagnostic considerations.

Clinical and Radiological Analysis of Pyogenic Vertebral Osteomyelitis Immediately after Successful Antimicrobial Therapy: Considerations for Assessing Therapeutic Response

Purpose: The clinical and radiological abnormal findings continue even after successful treatment in pyogenic vertebral osteomyelitis (PVO). We analyzed the clinical and radiological features of cured PVO based on ¹⁸F-fluorodeoxyglucose positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) and compared the radiological differences between FDG-PET and MRI for assessing therapeutic response in PVO. Methods: This study included 43 patients (28 men and 15 women) with lumbar PVO who had no recurrence after successful antimicrobial therapy. They were divided into two groups based on the location of maximum standardized FDG uptake value (SUV_max) of PVO lesion on FDG-PET/MRI when parenteral antibiotics were discontinued (31 in group A: Intervertebral structure; 12 in group B: Vertebral body and paravertebral muscle). The differences of clinical symptoms, hematological inflammatory indices, and radiological features were retrospectively analyzed. Results: The patients were treated with 42.28 ± 14.58 (21–89) days of parenteral antibiotics. There were significant differences in C-reactive protein (0.97 ± 1.10 vs. 0.51 ± 0.31 mg/dL, p = 0.041; normal range of CRP < 0.5), back pain (4.29 ± 1.13 vs. 3.50 ± 1.00, p = 0.040; visual analog scale), and SUV_max (4.34 ± 1.24 vs. 5.89 ± 1.57, p < 0.001) between the two groups. In the distribution pattern of PVO lesions, FDG-PET overall showed recovery pattern earlier than MRI did (p < 0.001). Conclusions: In cured PVO, the clinical features vary depending on the location of major structural damage of PVO lesion. The involvement of intervertebral structure is related with sustained back pain and elevation of CRP, and vertebral body/paravertebral muscle shows favorable clinical features despite advanced structural damages.

Phantom simulation of liver metastasis on a positron emission tomography with computed tomography scan after neoadjuvant chemoradiotherapy for distal esophageal cancer: a case report

Background

Neoadjuvant chemoradiotherapy is currently the gold standard treatment for esophageal cancer prior to surgery. This radiation therapy will sometimes lead to liver damage parallel to esophageal lesions, which mimics liver metastasis visualized by ¹⁸F-fluorodeoxyglucose positron emission tomography with computed tomography. In this report, we publish virtual radiation-induced liver damage images obtained during surgery, along with the coherent pathology, in order to confirm the false-positive result through an optimally decisive radiological examination.

Case presentation

We report a case of a Asian male patient with distal esophageal cancer who had undergone neoadjuvant chemoradiotherapy (5000 cGy). Subsequently, a new lesion was discovered during a positron emission tomography with computed tomography scan 6 weeks later, near the left caudate lobe of the liver during tumor restaging. To exclude the possibility of liver metastasis, serial imaging was conducted, which included liver sonography, computed tomography, and magnetic resonance imaging for a more intimate probe. The patient’s condition was verified as being liver inflammation change, as seen by the liver magnetic resonance imaging presentation. Thoracoscopic esophagectomy was performed with cervical esophagogastrostomy via the retrosternal route, along with a feeding jejunostomy. The procedure was performed smoothly, with an intraoperative liver biopsy also being conducted 2 weeks later, after positron emission tomography with computed tomography restaging. The pathology report revealed esophageal cancer in the form of poorly differentiated squamous cell carcinoma, pT3N1M0. The liver biopsy revealed obvious inflammation change after radiation therapy, which elucidated sinusoidal congestion with the attenuated hepatic cords and filled with erythrocytes. There was no evidence of liver metastasis. The patient recovered uneventfully and was discharged with his oral intake performing smoothly, and a stable condition was observed during 12 months of outpatient department follow-up.

Conclusions

New foci of increased ¹⁸F-fluorodeoxyglucose avidity are commonly seen in the caudate and left hepatic lobes of the liver during neoadjuvant chemoradiation for distal esophageal cancer, and these findings generally reflect radiation-induced liver disease rather than metastatic disease. Awareness of the pitfalls of a high ¹⁸F-fluorodeoxyglucose uptake in radiation-induced liver injury is crucial in order to avoid misinterpretation and overstaging. Except for the location of ¹⁸F-fluorodeoxyglucose uptake, the shape of the lesion, and an maximum standardized uptake value (> 10/h), a convincing liver magnetic resonance imaging scan or even a liver biopsy can provide accurate information for distinguishing radiotherapy-induced liver injury from liver metastasis.

Synthesis of 2'-paclitaxel 2-deoxy-2-fluoro-glucopyranosyl carbonate for specific targeted delivery to cancer cells

A novel 2-fluorodeoxyglucose conjugated derivative of paclitaxel was efficiently synthesized using a linker between 2'-OH of paclitaxel and C1-hydroxyl group of 2-fluorodeoxyglucose. In preparation of the prodrug, allyl carbonates were selected as the protective group and the efficient one-step removal of allyloxycarbonyl groups at the end of the synthesis using palladium chemistry gave the target molecule in good yield. The prodrug not only improved the pharmaceutical properties of paclitaxel, such as solubility and stability, but also demonstrated enhanced cytotoxicity and selectivity for cancer cells and less toxicity toward normal HUVEC cells.

Posttreatment FDG-Avid Splenic Lesions in DLBCL and HD: Clinical and Radiographic Characteristics for Risk Assessment

Residual end of treatment (EOT) FDG-avid lesions are often due to infectious or inflammatory process and not due to refractory lymphoma. Nonetheless, such lesions prompt diagnostic and therapeutic interventions. We evaluate clinical and radiological characteristics of patients with EOT FDG-avid splenic lesions. Comparing metabolic volume (MV) ratio between EOT to interim, showed a marked difference between false positive and true positive lesions (0.5 vs 3.6, P = 0.02). EOT SUVmax was also significantly different between the groups (7 vs. 19, P = 0.02). We suggest EOT/interim-MV ratio as a tool to identify patients at low risk of refractory disease allowing non-invasive surveillance.

The Impact of Obesity on Tumor Glucose Uptake in Breast and Lung Cancer

Obesity confers an increased incidence and poorer clinical prognosis in more than 10 cancer types. Paradoxically, obesity may provide protection from poor outcomes in lung cancer. Mechanisms for the obesity-cancer links are not fully elucidated, with altered glucose metabolism being a promising candidate. Using 18F-fluorodeoxyglucose positron-emission-tomography/computed tomography images from The Cancer Imaging Archive, we explored the relationship between body mass index (BMI) and glucose metabolism in several cancers. In 188 patients (BMI mean [SD] = 27.7 [5.1], range = 17.4-49.3 kg/m2), higher BMI was associated with greater tumor glucose uptake in breast cancer (r = 0.36; P = .02) and with lower tumor glucose uptake in non-small cell lung cancer (r = -0.26; P = .048) using two-sided Pearson correlations. No relationship was observed in soft tissue sarcoma or squamous cell carcinoma. Harnessing the National Cancer Institute's open-access database, we demonstrate altered tumor glucose metabolism as a potential mechanism for the detrimental and protective effects of obesity on breast and lung cancer, respectively.

Influence of Biological Parameters Assessed in [18F]FDG PET/CT on Overall Survival in Cervical Cancer Patients

AIM

The aim of this study was to estimate the influence of biological parameters assessed in [F]FDG PET/CT on overall survival (OS) in cervical cancer patients.

METHODS

Retrospective analysis was performed on a group of 371 patients with newly diagnosed and histologically confirmed cervical cancer. PET biological parameters in primary tumor including SUVmax, SUVmean, total lesion glycolysis (TLG), metabolic tumor volume (MTV), heterogeneity, and parameters referring both to primary tumor and metastatic lesions: SUVtotal, TLGtotal, and MTVtotal, were analyzed.

RESULTS

Based on PET/CT results, 3 subgroups were identified: cervical only-with disease limited only to the cervix (38%), +regional nodes-where increased glucose accumulation in addition to the cervical area was also observed in regional lymph nodes (36%), and +distal metastases-where PET scan showed a disseminated disease (26%). Depending on the stage of the disease, in the cervical-only group, 5-year survival rate was 86%; in the +regional nodes group, it was 80%; whereas in the +distal metastases group, 5-year survival rate was only 55%. However, based on Cox regression model, significant influence on OS was found only in heterogeneity of primary tumor; more inhomogeneous tumors suggest worse prognosis (0.25 ± 0.04 vs 0.16 ± 0.09, P < 0.001), SUVtotal (76.6 ± 130.1 vs 45.4 ± 73.4, P = 0.002), and MTVtotal (79.03 ± 88.27 vs 63.00 ± 83.80 cm, P = 0.03). For heterogeneity, cutoff point suggesting worse prognosis was 0.18; for SUVtotal, 52.3; and for MTVtotal, 66.55 cm.

CONCLUSIONS

Stage of disease assessed in [F]FDG PET/CT significantly influences survival rate in patients with cervical cancer. SUVtotal, MTVtotal, and heterogeneity of primary tumor are independent prognostic factors on OS in cervical cancer patients.

Patient Repositioning Reveals a Malignant Pleura Effusion Initially Mistaken as a Bone Metastasis on 18FDG PET/CT

A 70-year-old woman with breast cancer underwent F-FDG PET/CT for restaging. An FDG-avid focus corresponding to a rib on CT images was identified and interpreted as suggestive of an osseous metastasis. A PET/CT-guided biopsy was planned with the patient in prone position. Prone images demonstrated the FDG focus "moved" to the anterior chest and corresponding to pleural fluid. The diagnosis was altered from osseous metastases to pleural malignancy, and the bone biopsy was not performed. This case not only emphasizes the sensitivity of PET in the detection of malignancy, but also highlights the difficulty localizing small, mobile, FDG-avid foci.

Evolving Role of Novel Quantitative PET Techniques to Detect Radiation-Induced Complications

Radiation-induced normal tissue toxicities vary in terms of pathophysiologic determinants and timing of disease development, and they are influenced by the dose and radiation volume the critical organs receive, and the radiosensitivity of normal tissues and their baseline rate of cell turnover. Radiation-induced lung injury is dose limiting for the treatment of lung and thoracic cancers and can lead to fibrosis and potentially fatal pneumonitis. This article focuses on pulmonary and cardiovascular complications of radiation therapy and discusses how PET-based novel quantitative techniques can be used to detect these events earlier than current imaging modalities or clinical presentation allow.

Pitfalls of a Mixed Metabolic Response at PET/CT

Although the term mixed metabolic response is commonly used in PET/CT reports, it should be a red flag to reconsider the assumptions made by the PET scan reader. Fluorine 18 fluorodeoxyglucose (FDG) PET/CT is recognized as an accurate imaging method for detecting response to cancer therapies. Critical clinical decisions regarding therapy are dependent on accurate interpretation of findings. The use of standardized terminology for response assessment, such as that in the Positron Emission Tomography Response Criteria in Solid Tumors (PERCIST), is highly recommended. With PERCIST, treatment response is categorized as complete metabolic response, partial metabolic response, stable metabolic disease, or progressive metabolic disease. Mixed metabolic response is not included in PERCIST. Rather, it is used colloquially to describe a scenario in which scanning performed after systemic cancer therapy reveals divergent findings, with some tumor foci responding and others not responding or even seen progressing. In PERCIST, mixed metabolic response should be described as stable metabolic disease or progressive metabolic disease. However, the PET/CT reader may also wish to suggest that individual tumors have heterogeneous genetic and/or other characteristics and consequently a mixed response to therapy. The concept of tumor heterogeneity is gaining momentum in cancer research and thus possibly leading to options for therapy targeted to oligometastases that are not responding. However, the authors suggest exercising extreme caution when PET/CT findings appear at first to reflect what some might call a mixed response. In addition, they have found that FDG PET/CT findings are often confounding owing to the simultaneous presence of two or more unrelated disease processes. Common examples include synchronous neoplasms, inflammatory processes, and treatment-related effects. Thus, an apparent mixed response is a red flag to reconsider whether all of the FDG-avid findings are actually metastases of the same cancer. Common mimics of a mixed metabolic response that do not represent true tumor heterogeneity are highlighted to improve the FDG PET/CT reader's recognition of these lesions.^©RSNA, 2019.

Evaluation of [18F]FDG/[18F]FLT/[18F]FMISO-based micro-positron emission tomography in detection of liver metastasis in human colorectal cancer

INTRODUCTION

Positron emission tomography (PET) is extensively used in clinical oncology for tumor detection. This study aimed to explore the application of the radiotracers [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG), 3'-deoxy-3'- [¹⁸F]fluorothymidine ([¹⁸F]FLT), and [¹⁸F]fluoromisonidazole ([¹⁸F]FMISO) in the diagnosis and monitoring of hepatic metastasis in human colorectal cancer (CRC).

METHODS

A mouse model of human CRC with hepatic metastasis was established by intrasplenic implantation of human CRC cell lines LoVo or HCT8. Metastatic potential of these two cell lines was evaluated by wound healing assay in vitro and survival analysis. Uptake of radiotracers between LoVo and HCT8 cells and uptake of radiotracers in the resulting mouse tumor models were examined by in vivo and in vitro experiments. Uptake of each radiotracer in hepatic metastatic lesions was quantified and expressed as standard uptake value (SUV). Protein expression of multiple tumor biomarkers was determined in metastatic lesions. The correlation between tracer uptake and tumor marker expression was evaluated using linear regression.

RESULTS

LoVo cells exhibited a stronger metastatic potential and a higher radiotracer uptake ability than HCT8 cells, as evidenced by significantly greater wound closure percentage, shorter survival, higher incidence of liver metastases, and higher cellular radiotracer levels in LoVo cells or LoVo cell-xenografted mice. SUV values of [¹⁸F]FLT and [¹⁸F]FMISO, but not [¹⁸F]FDG, in LoVo cell-derived metastatic lesions were significantly greater than those in HCT8 lesions. Mechanistically, the expression of MACC1, HIF-1α, and GLUT-1(metastasis associated in colon cancer 1, MACC1; hypoxia-inducible factor 1-alpha, HIF-1α; and glucose transporter 1, GLUT-1, respectively) in LoVo cell-derived metastatic lesions was more effectively induced than in HCT8-derived ones. A linear regression analysis demonstrated significant positive correlations between [¹⁸F]FLT/[¹⁸F]FMISO uptake and tumor biomarker expression in metastatic tissues.

CONCLUSIONS

[¹⁸F]FLT and [¹⁸F]FMISO-based PET imaging may serve as a promising method for early detection and monitoring of hepatic metastasis in patients with CRC.

Utility of Molecular Imaging with 2-Deoxy-2-[Fluorine-18] Fluoro-DGlucose Positron Emission Tomography (18F-FDG PET) for Small Cell Lung Cancer (SCLC): A Radiation Oncology Perspective

BACKGROUND AND OBJECTIVE

Although accounting for a relatively small proportion of all lung cancers, small cell lung cancer (SCLC) remains to be a global health concern with grim prognosis. Radiotherapy (RT) plays a central role in SCLC management either as a curative or palliative therapeutic strategy. There has been considerable progress in RT of SCLC, thanks to improved imaging techniques leading to accurate target localization for precise delivery of RT. Positron emission tomography (PET) is increasingly used in oncology practice as a non-invasive molecular imaging modality.

METHODS

Herein, we review the utility of molecular imaging with 2-deoxy-2-[fluorine-18] fluoro-Dglucose PET (18F-FDG PET) for SCLC from a radiation oncology perspective.

RESULTS

There has been extensive research on the utility of PET for SCLC in terms of improved staging, restaging, treatment designation, patient selection for curative/palliative intent, target localization, response assessment, detection of residual/recurrent disease, and prediction of treatment outcomes.

CONCLUSION

PET provides useful functional information as a non-invasive molecular imaging modality and may be exploited to improve the management of patients with SCLC. Incorporation of PET/CT in staging of patients with SCLC may aid in optimal treatment allocation for an improved therapeutic ratio. From a radiation oncology perspective, combination of functional and anatomical data provided by integrated PET/CT improves discrimination between atelectasis and tumor, and assists in the designation of RT portals with its high accuracy to detect intrathoracic tumor and nodal disease. Utility of molecular imaging for SCLC should be further investigated in prospective randomized trials to acquire a higher level of evidence for future potential applications of PET.

Quantification of global lung inflammation using volumetric 18F-FDG PET/CT parameters in locally advanced non-small-cell lung cancer patients treated with concurrent chemoradiotherapy: a comparison of photon and proton radiation therapy

INTRODUCTION

Radiation pneumonitis is a major dose-limiting complication in thoracic radiation therapy (RT) and presents clinically in the first few months after RT. We evaluated the feasibility of quantifying pulmonary parenchymal glycolysis (PG) as a surrogate of global lung inflammation and radiation-induced pulmonary toxicity using a novel semiautomatic lung segmentation technique in non-small-cell lung cancer (NSCLC) patients and compared PG in patients treated with photon or proton RT.

PATIENTS AND METHODS

We evaluated 18 consecutive locally advanced NSCLC patients who underwent pretreatment and post-treatment F-FDG PET/CT treated with definitive (median: 66.6 Gy; 1.8 Gy fractions) photon or proton RT between 2010 and 2014. Lung volume segmentation was conducted using 3D Slicer by performing simple thresholding. Pulmonary PG was calculated by summing F-FDG uptake in the whole lung.

RESULTS

In nine patients treated with photon RT, significant increases in PG in both ipsilateral (mean difference: 1400±510; P=0.02) and contralateral (mean difference: 1200±450; P=0.03) lungs were noted. In nine patients treated with proton therapy, no increase in pulmonary PG was observed in either the ipsilateral (P=0.30) or contralateral lung (P=0.98).

CONCLUSION

We observed a significant increase in global lung inflammation bilaterally as measured by quantification of PG. However, no significant change in global lung inflammation was noted after proton therapy. Future larger studies are needed to determine whether this difference correlates with lower risks of radiation pneumonitis in NSCLC patients treated with proton therapy.

Potential for the blood-based biomarkers cytokeratin 19 fragment (CYFRA 21-1) and human epididymal protein 4 (HE4) to detect recurrence during monitoring after surgical resection of adenocarcinoma of the lung

OBJECTIVES

The biomarkers cytokeratin 19 fragment (CYFRA 21-1) and human epididymis protein 4 (HE4) are useful in the diagnosis, prognosis, and monitoring of non-small cell lung cancer (NSCLC), but their combination has not been investigated yet. The objective of this analysis was to evaluate the ability of CYFRA 21-1 and HE4 to predict recurrence as part of follow-up monitoring in patients with adenocarcinoma (ADC) of the lung.

MATERIALS AND METHODS

Serum samples were collected from patients with stage I-IIIA ADC preoperatively and during follow-up at 3, 6, 12, 18, and 24 months and then every 6-12 months up to 5 years post-R0 resection. Samples were analyzed for CYFRA 21-1 and HE4 via electrochemiluminescence immunoassay. All cases of disease recurrence were verified by imaging. The diagnostic performance of CYFRA 21-1, HE4, and their combination to predict recurrence was assessed by Receiver Operating Characteristic (ROC) and corresponding area under the curve (AUC).

RESULTS

115 patients with ADC were included (N = 612 biomarker measurements); median age was 63 years; most had stage I-II disease (n = 97; 84.3%). All patients underwent surgical resection; 44 patients (38%) also received adjuvant chemotherapy and 16 (14%) received radiation therapy. At the median timepoint for the last blood sample collection (37 months), 31 patients (27%) had experienced recurrence. Both CYFRA 21-1 and HE4 were able to detect recurrence (AUC and 95% confidence interval [CI]): 75.9% (66.0-85.8%) and 75.4% (65.9-84.8%), respectively, but this increased with the combination (78.8% [69.0-88.6%]). At a sensitivity of 80%, the respective specificities (95% CI) for CYFRA 21-1, HE4, and the combination were 57.1% (53.0-61.2%), 57.1% (53.0-61.2%), and 69.7% (65.8-73.4%).

CONCLUSION

Serial measurements of serum CYFRA 21-1 and HE4 levels could provide a valuable method for follow-up monitoring of patients with ADC to detect recurrence.

A prospective study of the feasibility of FDG-PET/CT imaging to quantify radiation-induced lung inflammation in locally advanced non-small cell lung cancer patients receiving proton or photon radiotherapy

PURPOSE

This prospective study assessed the feasibility of ¹⁸F-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography/computed tomography (PET/CT) to quantify radiation-induced lung inflammation in patients with locally advanced non-small cell lung cancer (NSCLC) who received radiotherapy (RT), and compared the differences in inflammation in the ipsilateral and contralateral lungs following proton and photon RT.

METHODS

Thirty-nine consecutive patients with NSCLC underwent FDG-PET/CT imaging before and after RT on a prospective study. A novel quantitative approach utilized regions of interest placed around the anatomical boundaries of the lung parenchyma and provided lung mean standardized uptake value (SUVmean), global lung glycolysis (GLG), global lung parenchymal glycolysis (GLPG) and total lung volume (LV). To quantify primary tumor metabolic response to RT, an adaptive contrast-oriented thresholding algorithm was applied to measure metabolically active tumor volume (MTV), tumor uncorrected SUVmean, tumor partial volume corrected SUVmean (tumor-PVC-SUVmean), and total lesion glycolysis (TLG). Parameters of FDG-PET/CT scans before and after RT were compared using two-tailed paired t-tests.

RESULTS

All tumor parameters after either proton or photon RT decreased significantly (p < 0.001). Among the 21 patients treated exclusively with proton RT, no significant increase in PVC-SUVmean or PVC-GLPG was observed in ipsilateral lungs after the PVC parameters of primary tumor were subtracted (p = 0.114 and p = 0.453, respectively). Also, there were no significant increases in SUVmean or GLG of contralateral lungs of patients who received proton RT (p = 0.841, p = 0.241, respectively). In contrast, among the nine patients who received photon RT, there was a statistically significant increase in PVC-GLPG of ipsilateral lung (p < 0.001) and in GLG of contralateral (p = 0.036) lung. In the subset of nine patients who received a combined proton and photon RT, there was a statistically significant increase in PVC-GLPG of ipsilateral lung (p < 0.001).

CONCLUSION

Our data suggest less induction of inflammatory response in both the ipsilateral and contralateral lungs of patients treated with proton compared to photon or combined proton-photon RT.

A Case of Liver Injury Mimicking Metastasis After Gamma Knife Therapy for Lung Cancer: Evaluating by 18F-FDG PET/CT

A 52-year-old man presented a mixed low-density lesion with high FDG uptake in hepatic segment VIII after gamma knife therapy for lung cancer, which was easily misdiagnosed as hepatic metastasis. Follow-up PET/CT assessment demonstrated that the hepatic lesion was barely observed and without FDG accumulation 5 months after radiotherapy. This case suggests that a new FDG-avid lesion at PET/CT after radiotherapy for lung cancer can be caused by radiation-induced liver injury. Knowledge of its imaging characteristics and nature course evaluated by follow-up PET/CT is critical to avoid misinterpretation of this lesion as metastases.

Evaluation of physiologic and abnormal glucose uptake in palatine tonsils: differential diagnostics with sequential dual-time-point 2-deoxy-2-[18F]FDG PET/CT

BACKGROUND

The aim of this article was to evaluate the usefulness of sequential dual-time-point 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (DTP [18F]FDG PET/CT) in distinguishing physiologic, inflammatory and malignant palatine tonsils as difficult to differentiate in the oncological practice.

METHODS

A total of 90 patients before the treatment underwent sequential DTP [18F]FDG PET/CT examinations. We analyzed 104 structures in 90 patients: 31 physiologic tonsils, 28 histopathologically confirmed inflammatory tonsils of non-specified origin, 31 histopathologically confirmed palatine tonsils cancer and 14 non-malignant contralateral tonsils in patients with histopathologically confirmed unilateral palatine tonsil malignancy. Patients underwent sequential [18F]FDG PET/CT examinations at 60 and 90 minutes post-injection of the [18F]FDG. We analyzed the SUVmax and SUVmean values at 60 and 90 minutes post-injection changes over time and the Retention Index (RI-SUVmax). To find the predictive SUV value and the RI cut-off between physiology, inflammatory and malignancy, we used the ROC analysis.

RESULTS

The average SUVmax values at 60 and 90minutes post-injection within physiologic palatine tonsils were 1.36±0.26 and 1.31±0.26, respectively, P>0.05. The average SUVmax values at 60 and 90 minutes post-injection within inflammatory and malignant tonsils were 3.74±1.45, 3.80±1.47 (P>0.05) and 5.19±2.19, 5.81±2.50 (P<0.05), respectively. The RI-SUVmax fluctuation over time were 5±28% within physiologic, -4±11% within contralateral non-malignant tonsils in patients with one tonsil involved, 2±11% within inflammatory and 13±13% within malignant tonsils.

CONCLUSIONS

The sequential dual-time-point [18F]FDG PET/CT examinations may increase the sensitivity and the specificity of the PET/CT method in differential palatine tonsils diagnosis.

Atypical 18F-FDG PET-CT uptake in the head and neck; a case-based pictorial review

Positron emission tomography - computed tomography (PET-CT) with fluorine-18-fluorodeoxy-d-glucose (¹⁸F-FDG) has an increasing role in head and neck imaging. Interpretation of ¹⁸F-FDG-tracer uptake in the head and neck requires an understanding of normal physiological patterns of tracer uptake, as well as knowledge of potential pitfalls and atypical patterns. This article presents a select series of unusual patterns of ¹⁸F-FDG uptake on PET-CT imaging of the head and neck.

[18F]-2-Fluoro-2-Deoxy-D-glucose-PET Assessment of Cervical Cancer

This article provides an overview of PET in cervical cancer, primarily with regard to the use of ¹⁸F-2-fluoro-2-deoxy-d-glucose-PET/computed tomography. A brief discussion of upcoming technologies, such as PET/MR imaging, is presented.

Fertility-sparing for young patients with gynecologic cancer: How MRI can guide patient selection prior to conservative management

Historically, cancer treatment has emphasized measures for the "cure" regardless of the long-term consequences. Advances in cancer detection and treatment have resulted in improved outcomes bringing to the fore various quality of life considerations including future fertility. For many young cancer patients, fertility preservation is now an integral component of clinical decision-making and treatment design. Optimal fertility-sparing options for young patients with gynecologic cancer are influenced by patient age, primary cancer, treatment regimens, and patient preferences. Possible approaches include embryo or oocyte cryopreservation, ovarian transposition, conservative surgery, and conservative medical treatment to delay radical surgery. These may be used alone or in combination to maximize fertility preservation. Awareness of the various fertility-sparing options, eligibility criteria, and the central role of magnetic resonance imaging in the proper selection of patients will enable radiologists to produce complete clinically relevant imaging reports and serve as effective consultants to referring clinicians. Knowledge of the potential imaging pitfalls is essential to avoid misinterpretation and guide appropriate management.

Clinical staging of malignant pleural mesothelioma: current perspectives

Malignant pleural mesothelioma (MPM) is a disease with limited therapeutic options, the management of which is still controversial. Diagnosis is usually made by thoracoscopy, which allows multiple biopsies with histological subtyping and is indicated for staging purposes in surgical candidates. The recommended and recently updated classification for clinical use is the TNM staging system established by the International Mesothelioma Interest Group and the International Association for the Study of Lung Cancer, which is based mainly on surgical and pathological variables, as well as on cross-sectional imaging. Contrast-enhanced computed tomography is the primary imaging procedure. Currently, the most used measurement system for MPM is the modified Response Evaluation Criteria in Solid Tumors (RECIST) method, which is based on unidimensional measurements of tumor thickness perpendicular to the chest wall or mediastinum. Magnetic resonance imaging and functional imaging with ¹⁸F-fluoro-2-deoxy-D-glucose positron-emission tomography can provide additional staging information in selected cases, although the usefulness of this method is limited in patients undergoing pleurodesis. Molecular reclassification of MPM and gene expression or miRNA prognostic models have the potential to improve prognostication and patient selection for a proper treatment algorithm; however, they await prospective validation to be introduced in clinical practice.

Role of Nuclear Medicine for Diagnosing Infection of Recently Implanted Lower Extremity Arthroplasties

Infection is an infrequent complication of lower extremity prosthetic joint surgery. Approximately one-third develop within 3 months (early), another third within 1 year (delayed), and the remainder more than 1 year (late) after surgery. Diagnosing prosthetic joint infection, especially in the early postoperative period during the first year, is challenging. Pain is almost always present. The presence of fever is variable, ranging from less than 5% to more than 40% of patients. Leukocytosis is a poor predictor of infection. After primary uncomplicated arthroplasty, the C-reactive protein remains elevated for up to 3 weeks. The erythrocyte sedimentation rate can remain elevated for up to 1 year. Although joint aspiration with culture, the definitive preoperative diagnostic procedure, is specific, its sensitivity is variable. Plain radiographs lack sensitivity and specificity. Radionuclide studies are useful for evaluating painful joint replacements, but data on their utility during the early postoperative period are limited. During the first year after arthroplasty insertion, the bone scan can exclude infection. It is a good "rule-out" test, but it is not reliable for "ruling in" infection. Gallium-67 accumulates in normally healing surgical incisions and in aseptic inflammation. With an accuracy of 60%-80% for diagnosing prosthetic joint infection, there is little role for this radiopharmaceutical for evaluating prosthetic joints, regardless of age. Although data about diagnosing prosthetic joint infection with ¹⁸F-FDG in the early postoperative period are lacking, uptake of this radiopharmaceutical in a variety of postoperative settings for variable time periods is well known. Furthermore, its utility for diagnosing prosthetic joint infection in general, after nearly 2 decades of investigation, remains to be established. Indium-111-labeled leukocytes do not accumulate in normally healing surgical wounds, and in combination with marrow imaging, the test is about 90% accurate for diagnosing prosthetic joint infection. Preliminary data indicate a comparable accuracy in the early postoperative period.

The role of PET/CT as a prognosticator and outcome predictor in lung cancer

Positron emission tomography/computed tomography (PET/CT) is an important imaging tool for management of lung cancer and can be utilized in diagnosis, staging, restaging, treatment planning and evaluating treatment response. In the past decade PET/CT has proven to be beneficial for the prediction of prognosis and outcome. PET findings before and after treatment, the quantitative PET parameters such as standardized uptake value (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) as well as delayed PET/CT imaging can be used to determine patient prognosis and outcome. Other tracers such as hypoxia and proliferation marker tracers may be used for prognostication. The prognostic factors derived from PET/CT imaging help early development of risk-adapted treatment strategies, which provides cost-effective treatment and leads to improved patient management. Here, we discuss findings of studies related to application of PET/CT in lung cancer as well as some technical updates on quantitative PET/CT in lung cancer.

Challenges in Interpretation of Staging PET/CT in Thoracic Malignancies

¹⁸F-fluorodeoxryglucose (¹⁸F-FDG) PET/CT imaging is routinely performed in the evaluation of patients with known or suspected thoracic malignancy. Indications for its use include staging of malignancy, assessment of response to therapy, evaluation of suspected disease recurrence, and evaluation of a solitary pulmonary nodule. In this article, we will discuss specific technical artifacts and also review potential pitfalls in the interpretation of PET/CT in thoracic malignancies including normal variations in physiologic uptake of FDG, benign conditions (such as infection, inflammation, posttreatment changes, and iatrogenic factors) that can result in increased FDG uptake, and malignancies that demonstrate scarce to no FDG uptake.

Whole-body MRI reveals high incidence of osteonecrosis in children treated for Hodgkin lymphoma

Osteonecrosis is a well-recognized complication in patients treated with corticosteroids. The incidence of osteonecrosis in children treated for Hodgkin lymphoma is unknown because prospective whole-body magnetic resonance imaging (MRI) studies are lacking in this patient population. Paediatric patients with newly diagnosed Hodgkin lymphoma who were treated according to a uniform paediatric Hodgkin protocol were eligible for inclusion in this prospective study. Whole-body MRI was performed in all 24 included patients (mean age 15·1 years, 12 girls) both before treatment and after 2 cycles of chemotherapy, and in 16 patients after completion of chemotherapy. Osteonecrosis was identified in 10 patients (41·7%, 95% confidence interval: 22·0-61·4%), with a total of 56 osteonecrotic sites. Osteonecrosis was detected in 8 patients after 2 cycles of OEPA (vincristine, etoposide, prednisone, doxorubicin), and in 2 additional patients after completion of chemotherapy. Epiphyseal involvement of long bones was seen in 4 of 10 children. None of the patients with osteonecrosis had any signs of bone collapse at the times of scanning. Whole-body MRI demonstrates osteonecrosis to be a common finding occurring during therapy response assessment of paediatric Hodgkin lymphoma. Detection of early epiphyseal osteonecrosis could allow for treatment before bone collapse and joint damage may occur.

Focal Hepatic Fluorodeoxyglucose Uptake Mimics Liver Metastasis Following External Beam Radiation for Gastroesophageal Cancers: A Case and Review of the Literature

Patients with locally advanced gastroesophageal cancers frequently undergo concurrent chemotherapy and radiation (CRT). 18-fluorodeoxyglucose-positron emission tomography (¹⁸FDG-PET) in combination with computed tomography is used for disease staging and assessing response to therapy. ¹⁸FDG-PET interpretation is subject to confounding influences including infectious/inflammatory conditions, serum glucose, and concurrent medications. Radiotherapy induces tissue damage, which may be associated with FDG-avidity; however, few reports have described the focal areas of hepatic uptake following concurrent chemoradiation (CRT). Distinguishing hepatic FDG uptake from disease progression represents an important clinical scenario. Here, we present two cases of unexpected FDG uptake in the liver after CRT and review the literature describing incidental liver uptake on FDG-PET.

The potential value of volume-based quantitative PET parameters and increased bone marrow uptake for the prediction of survival in patients with malignant pleural mesothelioma

PURPOSE

The aim of this study was to investigate the relationship between volume-based quantitative PET parameters and survival in patients with malignant pleural mesothelioma (MPM) and to evaluate the potential value of bone marrow (BM) uptake in predicting prognosis.

MATERIALS AND METHODS

We retrospectively reviewed the data of 51 patients with MPM who underwent initial staging by fluorine-18-fluorodeoxyglucose (F-FDG) PET/computerized tomography (PET/CT). F-FDG-PET images were visually and quantitatively re-evaluated and maximum standardized uptake values (SUVmax), mean standardized uptake values (SUVmean), metabolic tumor volume (MTV), total lesion glycolysis of primary tumors, and pleural thickening were calculated. In addition, BM and liver uptakes were measured; also, the degree of BM uptake was scored visually. BM/liver ratio and visual BM uptake score were noted. The correlations between quantitative PET parameters, BM uptake, and overall survival were analyzed.

RESULTS

F-FDG-PET scans upstaged 6 (11.8%) of 51 patients because of detection of previously unknown distant metastasis. On univariate analysis, advanced disease stage, high leukocyte count (≥10×10/ml), pleural thickening greater than 13 mm, SUVmax, SUVmean, MTV, total lesion glycolysis, BM/liver greater than 1.01, and visual score 1 and 2 were negative prognostic factors (P<0.05). In multivariate analysis, SUVmax greater than 8.6 [P=0.027, hazard ratio (HR): 2.961], MTV greater than 112 (P=0.001, HR: 4.861), and visual score 2 (P=0.035, HR: 3.827) were associated independently with a poor prognosis.

CONCLUSION

The presence of distant metastasis is more predictive of survival than PET nodal status in MPM patients. PET/CT has the potential to provide prognostic information in MPM patients and there was a good correlation between overall survival and volume-based PET parameters. Determination of BM uptake may contribute toward the prediction of patient outcome with other quantitative PET parameters.

PET/CT and MRI in the imaging assessment of cervical cancer

Imaging plays a central role in the evaluation of patients with cervical cancer and helps guide treatment decisions. The purpose of this pictorial review is to describe magnetic resonance (MR) imaging and positron emission tomography (PET)/computed tomography (CT) assessment of cervical cancer, including indications for imaging, important findings that may result in management change, as well as limitations of both modalities. The International Federation of Gynecology and Obstetrics cervical cancer staging system does not officially include imaging; however, the organization endorses the use of MR imaging and PET/CT in the management of patients with cervical cancer where these modalities are available. MR imaging provides the best visualization of the primary tumor and extent of soft tissue disease. PET/CT is recommended for assessment of nodal involvement, as well as distant metastases. Both MR imaging and PET/CT are used to follow patients post-treatment to assess for recurrence. This review focuses on the current MR imaging and PET/CT protocols, the utility of these modalities in assessing primary tumors and recurrences, with emphasis on imaging findings which change management and on imaging pitfalls to avoid. It is important to be familiar with the MR imaging and PET/CT appearance of the primary tumor and metastasis, as well as the imaging pitfalls, so that an accurate assessment of disease burden is made prior to treatment.

Imaging of acute and subacute toxicities of cancer therapy in children

Effective cancer therapies have resulted in significant improvement in survival. However, treatment-related acute and subacute complications are a cause of significant morbidity and mortality. Effects of cancer therapy in children can be seen early in the survival period or later in life in almost all organ systems of the body. Many of these conditions are evaluated by imaging and some are diagnosed based on characteristic imaging features. This article aims to discuss acute and subacute toxicities of cancer therapy in children involving multiple organ systems, pulmonary, gastrointestinal, hepatobiliary, genitourinary and musculoskeletal systems with emphasis on those in which imaging plays a role in diagnosis or management. We also discuss the role of imaging and choice of imaging modalities in these conditions.

Radiation Effects in the Mediastinum and Surroundings: Imaging Findings and Complications

Radiotherapy is one of the cornerstones for treatment of patients with cancer. Although advances in radiotherapy technology have considerably improved radiation delivery, potential adverse effects are still common. Postradiation changes to the mediastinum can include different structures such as the heart, great vessels, and esophagus. The purpose of the article was to illustrate the expected variety of changes to the mediastinum and adjacent lung resulting from external beam radiotherapy and radiotherapy-induced complications to the mediastinum and to discuss different radiotherapy delivery techniques.

Radiation-induced liver disease as a mimic of liver metastases at serial PET/CT during neoadjuvant chemoradiation of distal esophageal cancer

PURPOSE

To determine the frequency and appearance of radiation-induced liver disease on PET/CT in patients undergoing serial imaging during neoadjuvant chemoradiation of distal esophageal cancer.

MATERIALS AND METHODS

In this IRB-approved, HIPAA-compliant retrospective analysis, we identified 112 patients with distal esophageal cancer treated by neoadjuvant chemoradiation who had serial PET/CT imaging available for review. Two readers reviewed all studies in consensus and recorded those cases where new foci of visually detectable increased FDG avidity appeared in the liver during therapy. The etiology of such foci was determined from corresponding findings at CT or MRI, by hepatic biopsy during surgery, by characteristic evolution on post-operative imaging, or by a combination of these methods.

RESULTS

New foci of FDG avidity developed in the liver during neoadjuvant therapy in 10 of 112 (9%) patients, of whom nine (8%) were determined to have radiation-induced liver disease based on further imaging and/or biopsy and one of whom had developed interval metastatic disease based on biopsy. In the cases of radiation-induced liver disease, the abnormal foci were found only in the caudate and left hepatic lobes, near the primary tumor, while the patient who developed interval metastatic disease had involvement of the inferior right hepatic lobe, remote from the radiation therapy field.

CONCLUSION

New foci of increased FDG avidity are commonly seen in the caudate and left hepatic lobes of the liver during neoadjuvant chemoradiation of distal esophageal cancer, and these findings generally reflect radiation-induced liver disease rather than metastatic disease.

Allogeneic cell transplant expands bone marrow distribution by colonizing previously abandoned areas: an FDG PET/CT analysis

Mechanisms of hematopoietic reconstitution after bone marrow (BM) transplantation remain largely unknown. We applied a computational quantification software application to hybrid 18F-fluorodeoxyglucose positron emission tomography (PET)/computed tomography (CT) images to assess activity and distribution of the hematopoietic system throughout the whole skeleton of recently transplanted patients. Thirty-four patients underwent PET/CT 30 days after either adult stem cell transplantation (allogeneic cell transplantation [ACT]; n = 18) or cord blood transplantation (CBT; n = 16). Our software automatically recognized compact bone volume and trabecular bone volume (IBV) in CT slices. Within IBV, coregistered PET data were extracted to identify the active BM (ABM) from the inactive tissue. Patients were compared with 34 matched controls chosen among a published normalcy database. Whole body ABM increased in ACT and CBT when compared with controls (12.4 ± 3 and 12.8 ± 6.8 vs 8.1 ± 2.6 mL/kg of ideal body weight [IBW], P < .001). In long bones, ABM increased three- and sixfold in CBT and ACT, respectively, compared with controls (0.9 ± 0.9 and 1.7 ± 2.5 vs 0.3 ± 0.3 mL/kg IBW, P < .01). These data document an unexpected distribution of transplanted BM into previously abandoned BM sites.