18F-fluorodeoxyglucose Positron Emission Tomography-computed Tomography Research Articles

Giant Pilomatricoma Mistaken for a Malignant Tumor.

Pilomatricomas are tumors originating from the matrices of hair follicles. Giant pilomatricomas, defined as pilomatricomas that are 5cm or larger, are benign but may appear malignant clinically. We present the case of a 69-year-old man with a rapidly growing mass on his scalp. When he visited our department, the tumor measured 10.0×6.0×4.0cm and showed inflammation and ulceration. Magnetic resonance imaging and 18 F-fluorodeoxyglucose positron emission tomography-computed tomography showed findings resembling lymph node metastasis from a malignant tumor. However, upon an incisional biopsy, the tumor was diagnosed as a pilomatricoma. Therefore, we performed an excisional biopsy instead of radical surgery and lymph node dissection. The tumor was ultimately diagnosed as a giant pilomatricoma based on the excisional biopsy, and the patient received reconstruction only at the site of the defect. A giant pilomatricoma can be mistaken for a malignant tumor due to its characteristics. In such uncertain cases, it can be helpful to first perform an excisional biopsy.

Fecal microbiota composition is related to brown adipose tissue 18F-fluorodeoxyglucose uptake in young adults

ObjectiveHuman brown adipose tissue (BAT) has gained considerable attention as a potential therapeutic target for obesity and its related cardiometabolic diseases; however, whether the gut microbiota might be an efficient stimulus to activate BAT metabolism remains to be ascertained. We aimed to investigate the association of fecal microbiota composition with BAT volume and activity and mean radiodensity in young adults.Methods82 young adults (58 women, 21.8 ± 2.2 years old) participated in this cross-sectional study. DNA was extracted from fecal samples and 16S rRNA sequencing was performed to analyse the fecal microbiota composition. BAT was determined via a static 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography scan (PET/CT) after a 2 h personalized cooling protocol. 18F-FDG uptake was also quantified in white adipose tissue (WAT) and skeletal muscles.ResultsThe relative abundance of Akkermansia, Lachnospiraceae sp. and Ruminococcus genera was negatively correlated with BAT volume, BAT SUVmean and BAT SUVpeak (all rho ≤ − 0.232, P ≤ 0.027), whereas the relative abundance of Bifidobacterium genus was positively correlated with BAT SUVmean and BAT SUVpeak (all rho ≥ 0.262, P ≤ 0.012). On the other hand, the relative abundance of Sutterellaceae and Bifidobacteriaceae families was positively correlated with 18F-FDG uptake by WAT and skeletal muscles (all rho ≥ 0.213, P ≤ 0.042). All the analyses were adjusted for the PET/CT scan date as a proxy of seasonality.ConclusionOur results suggest that fecal microbiota composition is involved in the regulation of BAT and glucose uptake by other tissues in young adults. Further studies are needed to confirm these findings.Clinical trial informationClinicalTrials.gov no. NCT02365129 (registered 18 February 2015).

18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography Interpretation Criteria for the Assessment of Therapeutic Response in Patients with Advanced Stage of Lung Cancer: Inter-Reader Reliability, Accuracy, and Survival Outcomes.

18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET/CT) is useful in the evaluation of lung cancer (LC), both for staging and therapy assessment. However, for the evaluation of treatment response, shared criteria are not available. We proposed a 3-point score, similar to Deauville-score and compared its diagnostic accuracy with Hopkins criteria for the evaluation of treatment response in LC to validate a qualitative and simpler interpretation system. We retrospectively included 93 patients with advanced stage (III-IV) LC who underwent 18F-FDG-PET/CT after first-line treatment. Positron emission tomography/computed tomography (PET/CT) scans were interpreted according to a 3-point scale-like Deauville score criteria (score 1 = uptake lower than blood-pool activity; score 2 = uptake higher than blood-pool but lower than liver activity; score 3 = uptake higher than liver). Inter-reader variability was assessed using percent agreement and kappa statistics. Kaplan-Meier plots with a Mantel-Cox log-rank test were performed, considering death as the endpoint. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of like Deauville-like score criteria were 82,76% (95% confidence interval [CI] 70.5%-91.4%), 80% (95% CI 28.3%-99%), 97.9% (95% CI 89.2%-99.6%), 28.6%(95% CI 16.38%-44.9%), and 82.5% (95% CI 70.9-90.9%), respectively. Applying Hopkins criteria score we obtained sensitivity, specificity, PPV, NPV, and accuracy of 81% [95% CI 68.6%-90.1%), 100% (95% CI 47.2-100%), 100% (95% CI %), 31.3% (95% CI 21.0%-43%), and 82.5%(95% CI 70.9%-90.9%), respectively. There was a high agreement between the two readers both using Hopkins criteria (k = 0.912) and like-Deauville-score criteria (k = 0.956). Applying 3-point-scale criteria, patients with positive PET/CT after therapy had significantly shorter lower survival (P = 0.0021). The application of 3-point scale criteria for posttherapy assessment in patients with advanced stage of LC represents an easy and reproducible method with optimal inter-observer agreement and great PPV and accuracy.

Accuracy of Response Assessment FDG PET-CT Post (Chemo)Radiotherapy in HPV Negative Oropharynx Squamous Cell Carcinoma.

Simple SummaryOropharyngeal squamous cell carcinoma is often treated with (chemo)radiotherapy with curative intent. Human papilloma virus (HPV) is a key risk factor for the development of a majority of oropharynx cancers in many parts of the world. PET-CT is widely used as an accurate method of assessing response following (chemo)radiotherapy and most of the data supporting this is based upon HPV-related disease. Oropharynx squamous cell carcinoma that is not related to human papilloma virus has an inferior prognosis and there is little data regarding the accuracy of response assessment PET-CT after chemoradiotherapy. This study shows that a negative PET-CT after treatment for patients with HPV-negative oropharynx cancer has a high negative predictive value with treatment having been successsful; however if the PET-CT is equivocal there is a significant chance of disease being persistent.Background: Data on the accuracy of response assessment 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography-computed tomography (PET-CT) following (chemo)radiotherapy in patients with oropharynx squamous cell carcinoma (OPSCC) is predominantly based on HPV-positive disease. There is a paucity of data for HPV-negative disease, which has a less favourable prognosis. Methods: 96 patients treated with (chemo)radiotherapy for HPV-negative OPSCC with baseline and response assessment FDG PET-CT between 2013–2020, were analysed. PET-CT response was classified as negative, equivocal, or positive based on qualitative reporting. PET-CT response categories were analysed with reference to clinicopathological outcomes. Test characteristics were evaluated, comparing negative results to equivocal and positive results together. Post-test probabilities were calculated separately for positive and equivocal or negative results. Results: Median follow-up was 26 months. The negative predictive value of a negative scan was 93.7 and 93.2%, respectively, for primary tumour and nodal disease. For a negative scan, the post-test probability was 0.06 for primary and 0.07 for nodal disease. The post-test probability of an equivocal scan was 0.51 and 0.72 for primary and lymph node, respectively. The post-test probability of a positive scan approached 1. For patients with/without a negative scan, two-year overall survival and progression-free survival were 83% versus 30% and 79% versus 17% (p < 0.001), respectively. Conclusion: The NPV of a negative response assessment PET-CT in HPV-negative OPSCC is high, supporting a strategy of clinical monitoring. Contrasting with the published literature for HPV-positive OPSCC, an equivocal response scan was associated with a moderate rate of residual disease.

Combination of Circulating Cell-Free DNA and Positron Emission Tomography to Distinguish Non-Small Cell Lung Cancer from Tuberculosis.

Non-small cell lung cancer (NSCLC) holds high metabolic tumor burden and circulating cell-free DNA (cfDNA) levels, and the relationship between metabolic tumor burden and cfDNA in NSCLC and the underlying mechanism of their interaction therein remain poorly characterized. Our aim was to evaluate the clinical value of cfDNA and metabolic tumor burden by positron emission tomography-computed tomography (PET/CT) for NSCLC differential diagnosis from tuberculosis in patients with solitary pulmonary nodules. Metabolic tumor burden values in humans (subjects with NSCLC, subjects with tuberculosis, and healthy control subjects) and relevant mouse models were detected by preoperative 18F-fluorodeoxyglucose PET (18F-FDG PET/CT) and [3H]-2-deoxy-DG uptake, respectively. The cfDNA levels were detected by quantifying serum cfDNA fragments from the ALU (115 bp) gene using reverse transcription-polymerase chain reaction. RNA sequence was performed to determine the underlying target genes and knocked down or inhibited the target genes in vivo and in vitro to determine the mechanism therein. Metabolic tumor burden correlated with serum cfDNA levels in NSCLC subjects but not in tuberculosis subjects or healthy controls. Mouse models showed a similar phenomenon. In addition, the RNA sequence showed that glucose transporter 1 (GLU1), factor-related apoptosis ligand (FasL), caspase 8, and caspase 3 were significantly increased in NSCLC mouse tumors compared with those in tuberculosis mouse masses. Inhibiting the metabolic tumor burden by blocking or knocking down GLU1 markedly reduced the expression of FasL, the phosphorylation of caspase 8/caspase 3, and serum cfDNA levels/apoptosis percentage in vivo and in vitro. Furthermore, the use of a combination of cfDNA and metabolic tumor burden allowed better ability to distinguish NSCLC subjects from those with tuberculosis or healthy controls than either method used alone. Metabolic tumor burden promotes the formation of circulating cfDNA through GLU1-mediated apoptosis in NSCLC, and the combination of cfDNA and metabolic tumor burden could be valuable for distinguishing NSCLC from tuberculosis.

A rare brainstem anaplastic astrocytoma

BackgroundAnaplastic astrocytoma (AA) is rarely observed in the brainstem and the clinical symptoms and imaging manifestations vary, which present a great challenge to accurate clinical diagnosis.Case descriptionA 56-year-old woman, with a month-long history of nausea and vomiting, was first diagnosed with acute cerebral infarction and demyelinating disease. The patient showed negative results on enhanced magnetic resonance and 18F-fluorodeoxyglucose positron emission tomography-computed tomography, and the clinical symptoms were not typical, leading to early misdiagnosis.ConclusionFinally, the patient was diagnosed with AA by pathological biopsy.

End-of-Treatment FDG PET-CT (EOT-PET) in Patients with Post-Chemotherapy Masses for Seminoma: Can We Avoid Further Intervention?

Anjana JoelContext Patients with seminoma present with advanced disease. End-of-treatment (EOT) positron emission tomography-computed tomography (PET-CT) is done to assess response and direct management of post-chemotherapy residual masses. Purpose This article assesses the utility of EOT PET-CT in the management of post-chemotherapy residual lymph nodal masses seminoma. Materials and Methods We analyzed all patients with seminoma who underwent an EOT PET-CT from January 2015 to January 2020 at our center and calculated the positive predictive value (PPV) and negative predictive value (NPV) of EOT PET-CT in the entire cohort of patients and among subgroups. Results A total of 34 male patients underwent EOT PET-CT. Fourteen (41.2%) were stratified as good risk and 20 (58.8%) as intermediate risk. The median follow-up was 23 months (interquartile range: 9.75-53 months). In 23 patients there were residual masses of size more than 3 cm at the EOT PET scan. EOT PET was positive as per the SEMPET criteria in 18 (78%) out of 23 patients. None underwent retroperitoneal lymph node dissection. All four who underwent image-guided biopsy, showed only necrosis on pathology. One patient with positive mediastinal node (standardized uptake value 13.6) had granulomatous inflammation. There was no relapse or progression during this period of follow-up. The NPV for EOT PET-CT for the entire cohort, > 3 cm, and > 6 weeks cutoff were 100%, respectively. The PPV for EOT PET-CT for the entire cohort, > 3 cm residual mass, and > 6 weeks cutoff were 8.7, 11.11, and 6.67%, respectively. Conclusion EOT PET-CT has a low PPV and high NPV in predicting viable tumor in post-chemotherapy residual masses among patients with seminomatous germ cell tumors. If required, EOT PET positivity can be confirmed by a biopsy or reassessed with a repeat PET-CT imaging to document persistent disease prior to further intervention.

Usefulness and potential pitfalls of pre-operative PET-CT in patients with endometrial cancer undergoing one- and two-step sentinel lymph node mapping: Do negative findings on PET-CT negativity really indicate node negativity?

ObjectiveWe investigated the utility of Positron emission tomography-Computed tomography (PET-CT) in the setting of two different sentinel lymph node (SLN) mapping techniques; the conventional cervical injection method (one-step) and the two-step method, which involves fundal injection followed by cervical injection. MethodsPatients with endometrial cancer undergoing FDG PET-CT followed by laparoscopic or robotic surgical staging with SLN mapping at the Yonsei Cancer Center between July 2014 and April 2021 were stratified into the PET-positive group (with suspected or likely lymph nodes metastasis) and PET-negative group. A chart review was performed for the number of harvested SLNs, patterns of SLN metastases, and recurrence. ResultsAmong 466 patients undergoing one-step (n = 276) and two-step (n = 190) SLN mapping, LN metastasis was identified in 21 of 434 PET-negative and 18 of 32 PET-positive patients. The sensitivity and specificity of PET-CT for diagnosing lymph node metastasis were 46.2% and 96.7%, respectively. Among PET-positive patients with LN metastasis, anatomical distribution was concordant in 14/18 patients (77.8%). Among PET-negative patients, four (2.3%) had metastatic para-aortic SLNs, including three (1.7%) with isolated para-aortic metastases; metastatic para-aortic SLNs were exclusively found in the two-step group. Among PET-positive patients, para-aortic SLN metastasis was identified in 35.7% of two-step and 16.7% of one-step group. Among the 21 PET false-negative patients, recurrence was seen in four patients (19%) after a median follow-up of 34 months (range: 7–70 months). ConclusionsPET-CT served as a useful guide to clinicians with high anatomical concordance rate in patients with LN metastasis. However, despite high specificity, sensitivity was limited. SLN metastasis pattern, especially at the para-aortic level, indicates that the two-step SLN technique might be useful in PET-negative and PET-positive patients.

18F-FDG PET/CT and HRCT: a combined tool for risk stratification in idiopathic inflammatory myopathy-associated interstitial lung disease.

Rapidly progressive interstitial lung disease (RP-ILD) is a life-threatening form of idiopathic inflammatory myopathy (IIM)-associated interstitial lung disease (ILD). We aimed to assess the combination of 18F-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) and high-resolution computed tomography (HRCT) for the quantification of IIM-ILD activity and risk stratification for RP-ILD. Patients with IIM and undergoing 18F-FDG PET/CT were included in this retrospective study. Pulmonary FDG uptake was assessed using the maximum standardized uptake value (SUVlung) and visual score (PET score). HRCT was evaluated using visual analysis (HRCT score). Multivariable logistic regression was used to identify risk factors for RP-ILD. Seventy-three patients with IIM (17 with RP-ILD, 38 with non-RP-ILD, and 18 without ILD) were included. SUVlung, PET score, and HRCT score were significantly higher in RP-ILD than in non-RP-ILD. Strong positive correlations were observed between SUVlung, PET score, and the HRCT parameters. The area under the curve (AUC) of the PET score to differentiate between RP-ILD and non-RP-ILD (AUC = 0.860) was higher than that of the SUVlung (AUC = 0.802) and HRCT scores (AUC = 0.806). We developed a risk score based on the number of positive risk factors (PET score > 18, HRCT score > 140, and positive anti-melanoma differentiation-associated gene 5 (MDA5) antibody) to differentiate between RP-ILD and non-RP-ILD (AUC = 0.955). Patients with higher risk scores had significantly worse prognoses. 18F-FDG PET/CT is useful for assessing disease activity in patients with IIM-ILD. The combination of PET score, HRCT score, and anti-MDA5 antibody can be used to identify patients at increased risk of RP-ILD and with poor prognoses.

Pancreatic involvement in Erdheim-Chester disease: a case report and review of the literature

BackgroundErdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis characterized by infiltration of lipid-laden foamy macrophages within different tissues. Clinical manifestations of ECD are highly heterogeneous. Bone lesions are found in 80%-95% of patients, while extraosseous lesions usually involve the cardiovascular system, retroperitoneum, central nervous system (CNS), and skin. Pancreatic involvement in ECD has barely been reported.Case presentationA 29-year-old female initially presented with menoxenia, diabetes insipidus and diabetes mellitus. 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET/CT) revealed hypermetabolic foci in the bilateral frontal lobe, saddle area, and pancreas. A 99mTc-MDP bone scrintigraphy scan revealed symmetrical increased uptake in distal femoral and proximal tibial metaphysis, which was confirmed to be osteosclerosis by high-resolution peripheral quantitative computed tomography. The patient underwent incomplete resection of the sellar mass. Histological examination of biopsies showed histiocytic aggregates, which were positive for S100 and negative for CD1a and CD207 on immunohistochemistry. Enhanced abdominal CT scan showed hypointense nodules within the body and tail of the pancreas. Endoscopic ultrasonography guided fine-needle aspiration (EUS-FNA) found no evidence of malignancy. She was diagnosed with ECD and treated with high-dose IFN-α. Repeated examinations at three-and eight-months post treatment revealed markedly reduction of both intracranial and pancreatic lesions.ConclusionsECD is a rare histiocytic neoplasm that can involve almost every organ, whereas pancreatic involvement has barely been reported to date. Here, we present the rare case of pancreatic lesions in ECD that responded well to interferon-α. We further reviewed reports of pancreatic involvement in histiocytic disorders and concluded the characteristics of such lesions to help diagnosis and treatment, in which these lesions mimicked pancreatic adenocarcinoma and caused unnecessary invasive surgeries.

Appropriate Diagnostic Approach in Patients with Suspicious Bone Metastasis from Low FDG-Avid Primary site in Thyroid gland: Case report

Metastatic bone tumors are the most common malignant tumor involving bone. Bone metastases from primary tumors of unknown origin are commonly attributed to prostate, breast, lung, and thyroid. 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography- Computed Tomography (PET-CT) has a very useful imaging modality to identify primary site in patients with suspicious bone metastasis. However, it remained unclear whether PET-CT have clinical value to identify primary site because some cancer types have low FDG-avidity. We report a case of 84-year-old female patient presenting with metastatic bone tumor in skull without showing any metabolic activity in primary site of her thyroid gland on FDG PET-CT and we discussed how to use other clinical information in this patient. Bangladesh J. Nuclear Med. 23(1&amp;2): 63-66, 2020

Severe thyrotoxicosis as initial presentation of gastric choriocarcinoma: a case report

BackgroundExtragonadal choriocarcinoma is rare and can be associated with hyperthyroidism when producing very high levels of human chorionic gonadotropin.Case presentationA 62-year-old Hispanic female presented with a 3-week history of shortness of breath, palpitations, extreme weakness, new-onset hot flashes, and right flank pain. Her physical examination was remarkable for tachycardia, hepatomegaly, hyperreflexia, and tremor; goiter was absent. Laboratory studies revealed increased lactate dehydrogenase, alkaline phosphatase, suppressed thyroid stimulating hormone, very elevated T4, and absent thyroid stimulating immunoglobulin. 18F-fluorodeoxyglucose positron emission tomography-computed tomography exhibited hepatomegaly with multiple large fluorodeoxyglucose-avid liver masses and a focus of fluorodeoxyglucose avidity in the stomach with no structural correlate. A thyroid scan (99mTcO4−) showed diffusely increased tracer uptake. She was started on propranolol and methimazole. Upon stabilization of severe thyrotoxicosis, upper endoscopy was performed, showing a ~ 5 cm bleeding lesion in the greater stomach curvature body; biopsy was consistent with choriocarcinoma; beta-human chorionic gonadotropin hormone was 2,408,171 mIU/mL. The patient received methotrexate followed by etoposide and cisplatin. Methimazole was titrated down, and upon liver failure the medication was stopped. The thyrotoxicosis was effectively controlled with antithyroid drug and concurrent chemotherapy. At ~ 1.5 months after initial diagnosis, the patient died due to bleeding/acute liver failure with coagulation defects followed by multiple organ failure.ConclusionsSevere thyrotoxicosis can represent an unusual initial presentation of metastatic choriocarcinoma in the setting of extreme elevation of beta-human chorionic gonadotropin. Primary gastric choriocarcinoma is an aggressive malignancy with very poor outcomes. The co-occurrence of severe thyrotoxicosis with advanced primary gastric choriocarcinoma and imminent liver failure complicates management options.

High-Grade Esophageal Neuroendocrine Neoplasm with Waxing and Waning Disease Course and Differential Response to Chemotherapy

Esophageal neuroendocrine neoplasms (NENs) are uncommon type of esophageal malignancies. We describe the clinical course and molecular imaging features of the relatively rare esophageal malignancy (an aggressive poorly differentiated NEN) that was widely metastatic at the initial presentation. The patient underwent multiple cycles of chemotherapeutic regimens, employing cisplatin-etoposide and nanopaclitaxel-carboplatin and later on rechallenge with cisplatin-etoposide. There was observation of fluctuating disease course and differential characteristics of tumor lesions in terms of treatment response and recurrences with multiple cycles of chemotherapy. In view of the histopathology of high Mib-1 labeling index and dual tracer positron emission tomography-computed tomography (PET-CT) (flurodeoxyglucose [FDG] and 68Ga-DOTATATE) features, the patient was not a suitable candidate for 177Lu-DOTATATE PRRT and FDG PET-CT was the preferred imaging modality for both treatment response assessment and disease monitoring in this patient. The varying response among metastatic lesions in the same individual (with one lesion showing partial response and the other one demonstrating disease progression) was an additional noteworthy feature of the case.

Fluorodeoxyglucose Positron Emission Tomography Imaging in Pneumocystis jiroveci Pneumonia.

Fever or pyrexia of unknown origin (PUO) is commonly defined as body temperature higher than 38.3°C on several occasions for a period of at least 3 weeks with uncertain diagnosis after initial routine obligatory investigations. In most cases of PUO, there is an uncommon presentation of a common disease which includes infection, noninfectious inflammatory diseases, malignancy, and miscellaneous causes. We present an interesting case of a 48-year-old man with PUO, who is a known case of multiple myeloma on immunosuppressive therapy, where 18F-fluorodeoxyglucose positron emission tomography-computed tomography was able to detect occult cause of infective etiology.

Stereotactic radiotherapy for adrenal oligometastases.

Approximately 50% of melanomas, 30–40% of lung and breast cancers and 10–20% of renal and gastrointestinal tumors metastasize to the adrenal gland.Metastatic adrenal involvement is diagnosed by computed tomography (CT ) with contrast medium, ultrasound (which does not explore the left adrenal gland well), magnetic resonance imaging (MRI) with contrast medium and 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18FDGPET-CT ) which also evaluates lesion uptake. The simulation CT should be performed with contrast medium; an oral bolus of contrast medium is useful, given adrenal gland proximity to the duodenum. The simulation CT may be merged with PET-CT images with 18FDG in order to evaluate uptaking areas. In contouring, the radiologically visible and/or uptaking lesion provides the gross tumor volume (GTV ). Appropriate techniques are needed to overcome target motion. Single fraction stereotactic radiotherapy (SRT ) with median doses of 16–23 Gy is rarely used. More common are doses of 25–48 Gy in 3–10 fractions although 3 or 5 fractions are preferred. Local control at 1 and 2 years ranges from 44 to 100% and from 27 to 100%, respectively. The local control rate is as high as 90%, remaining stable during follow-up when BED10Gy is equal to or greater than 100 Gy. SRT-related toxicity is mild, consisting mainly of gastrointestinal disorders, local pain and fatigue. Adrenal insufficiency is rare.

Metastatic Malignant Melanoma to Colon from Cutaneous Melanoma: A Case Report

Metastatic melanoma to the Gastrointestinal (GI) tract is rare and the colon is a less common site of GI tract metastasis for this cancer. We report a case of a 76-year-old male with history of cutaneous malignant melanoma since 2018 and two years later he developed metastasizing to the brain, axillary lymph node and descending colon. He was treated with stereotactic radiosurgery (SRS) for single brain metastasis, he subsequently underwent a combined left axillary node dissection and left colectomy. Importance of long-term surveillance and role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) and colonoscopy are discussed along with the role of surgical resection in improving survival. Nevertheless, metastatic malignant melanoma to the colon is difficult to identify diagnosis and treatment, multidisciplinary team discussion is necessary to determine the most appropriate treatment strategy.

Metastatic Malignant Melanoma to Colon from Cutaneous Melanoma: A Case Report

Metastatic melanoma to the Gastrointestinal (GI) tract is rare and the colon is a less common site of GI tract metastasis for this cancer. We report a case of a 76-year-old male with history of cutaneous malignant melanoma since 2018 and two years later he developed metastasizing to the brain, axillary lymph node and descending colon. He was treated with stereotactic radiosurgery (SRS) for single brain metastasis, he subsequently underwent a combined left axillary node dissection and left colectomy. Importance of long-term surveillance and role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) and colonoscopy are discussed along with the role of surgical resection in improving survival. Nevertheless, metastatic malignant melanoma to the colon is difficult to identify diagnosis and treatment, multidisciplinary team discussion is necessary to determine the most appropriate treatment strategy.

Is There a Role for [18F]FDG PET-CT in Staging MALT Lymphoma?

Simple SummaryMALT lymphoma represents a relatively rare lymphoma subtype that arises in different extranodal anatomic locations. In the current paper we summarize our experience in assessing disease extent and metabolic characteristics of MALT lymphomas with [18F]FDG PET-CT at staging, and aim to highlight the strengths and challenges this imaging modality poses. In our data, all extranodal lesions located in subcutaneous-tissue, lung and liver were detected on PET, while some of those located in other tissues (such as along the digestive tract) were not detected on PET. We also evaluated the predictive role of PET in these patients, and found that increased [18F]FDG-uptake in extranodal lesions was associated with worse disease progression.The role of 18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography—computed tomography (PET-CT) in assessing mucosa-associated lymphoid tissue (MALT) lymphoma is debatable. We retrospectively explored the role of [18F]FDG PET-CT in staging and predicting progression-free-survival (PFS) of patients with newly-diagnosed MALT lymphoma. Sixty-six studies were included. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were documented in the “hottest” extranodal and nodal lesions. Extranodal lesions and accompanying nodal disease were detected on PET in 38/66 (57.6%) and 13/66 (19.7%) studies, respectively. Detection rate of extranodal lesions differed significantly between those located in tissues with high/heterogeneous (e.g., stomach) vs low/homogenous (e.g., subcutaneous-tissue, lung) physiologic [18F]FDG-uptake (40.4% vs. 100%, p < 0.01). Nodal lesions had significantly lower SUVmax, MTV and TLG compared with extrandodal lesions in the same patients. Detection and [18F]FDG-avidity of extranodal lesions were higher in patients with advanced, bulky disease and concomitant marrow/nodal involvement. Increased SUVmax of extranodal lesions predicted shorter PFS (HR 1.10, 95% CI 1.01–1.19, p = 0.02). Higher SUVmax and TLG showed trends towards shorter PFS in patients with localized disease. In conclusion, detection rate of extranodal MALT lymphoma lesions located in tissues with low/homogeneous physiologic [18F]FDG-uptake is excellent on [18F]FDG PET-CT. When detected, SUVmax of extranodal lesions may predict PFS.

Port-Site Metastases in Incidentally Detected Carcinoma Gall Bladder: Role of 18F-FDG PET/CT and Patient Outcome.

Incidentally detected gall bladder carcinoma (IGBC) is occasionally encountered after cholecystectomy for benign gall bladder disease. Rarely these patients may present with port-site metastases (PSM) in follow-up. We retrospectively assessed the role of 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET/CT) in them. We aimed to determine the clinical outcome and correlate the survival based on FDG PET/CT findings. We did a single-center retrospective study in IGBC patients presented with histopathologically proven PSM. FDG PET/CT was done for restaging. The metastatic burden was evaluated. Survival after PSM and overall survival (OS) were assessed in different disease groups. A total of 22 patients (51.86 ± 12.04years) were included in the study. The mean interval between LC and PSM was 336.7 ± 501.9days. On FDG PET/CT, isolated single PSM was noted in 21 (95.5%) patients. Apart from PSM, abdominal lymph nodes, GB fossa lesion, and liver metastases were noted in the 10 (45.5%), 6 ( 27.3%), and 7 (31.8%) patients, respectively. FDG PET/CT revealed intra-abdominal disease and visceral metastasis in 11 (50%) and 10 (45.5%) patients. Nineteen (86.4%) patients died in follow-up with a median survival of 328.50 (225.25-804.0) day after PSM. Median OS after LC was 687.00 (362.50-1047.0) days. Patients with PSM plus disease (432.0days, 255.9-608.1), extra-abdominal metastases (400.0days, 316.9-483.1), and visceral metastases (400.0days, 296.2-503.8) had significantly lower OS compared to isolated PSM (1763days, p = 0.013), the intra-abdominal disease (996.0days, 753.2-1238.8, p = 0.0340), and non visceral metastasis (807.0days, 467.5-1146.4, p = 0.037). IGBC presenting as PSM is a distinct clinical entity. FDG PET/CT as functional imaging evaluates the local and metastatic disease burden. There is significantly lower survival in patients with PSM plus disease, extra-abdominal metastases, or visceral metastases. FDG PET/CT was an important prognostic marker in these patients and could help in management.

Characterization of focal hypermetabolic thyroid incidentaloma: An analysis with F-18 fluorodeoxyglucose positron emission tomography/computed tomography parameters.

BACKGROUNDIncidentally found thyroid tumor (thyroid incidentaloma, TI) on F-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) is reported in 2.5%-5% of patients being investigated for non-thyroid purposes. Up to 50% of these cases have been diagnosed to be malignant by cytological/histological results. Ultrasonography (US) and fine-needle aspiration cytology are recommended for thyroid nodules with high FDG uptake (hypermetabolism) that are 1 cm or greater in size. It is important to accurately determine whether a suspicious hypermetabolic TI is malignant or benign.AIMTo distinguish malignant hypermetabolic TIs from benign disease by analyzing F-18 FDG PET-CT parameters and to identify a cut-off value.METHODSTotally, 12761 images of patients who underwent F-18 FDG PET-CT for non-thyroid purposes at our hospital between January 2016 and December 2020 were retrospectively reviewed, and 339 patients [185 men (mean age: 68 ± 11.2) and 154 women (mean age: 63 ± 15.0)] were found to have abnormal, either focal or diffuse, thyroid FDG uptake. After a thorough review of their medical records, US, and cytological/histological reports, 46 eligible patients with focal hypermetabolic TI were included in this study. The TIs were categorized as malignant and benign according to the cytological/histological reports, and four PET parameters [standardized uptake value (SUV)max, SUVpeak, SUVmean, and metabolic tumor volume (MTV)] were measured on FDG PET-CT. Total lesion glycolysis (TLG) was calculated by multiplying the SUVmean by MTV. Both parametric and non-parametric methods were used to compare the five parameters between malignant and benign lesions. Receiver operating characteristic (ROC) curve analysis was performed to identify a cut-off value.RESULTSEach of the 46 patients [12 men (26.1%; mean age: 62 ± 13.1 years) and 34 women (73.9%; mean age: 60 ± 12.0 years)] with focal hypermetabolic TIs had one focal hypermetabolic TI. Among them, 26 (56.5%) were malignant and 20 (43.5%) were benign. SUVmax, SUVpeak, SUVmean, and TLG were all higher in malignant lesions than benign ones, but the difference was statistically significant (P = 0.012) only for SUVmax. There was a positive linear correlation (r = 0.339) between SUVmax and the diagnosis of malignancy. ROC curve analysis for SUVmax revealed an area under the curve of 0.702 (P < 0.05, 95% confidence interval: 0.550-0.855) and SUVmax cut-off of 8.5 with a sensitivity of 0.615 and a specificity of 0.789.CONCLUSIONMore than half of focal hypermetabolic TIs on F-18 FDG PET-CT were revealed as malignant lesions, and SUVmax was the best parameter for discriminating between malignant and benign disease. Unexpected focal hypermetabolic TIs with the SUVmax above the cut-off value of 8.5 may have a greater than 70% chance of malignancy; therefore, further active assessment is required.