Lymphomatous involvement of gastrointestinal tract： Evaluation by positron emission tomography with ^18F-fluorodeoxyglucose

AIM: To demonstrate the 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) findings in patients with non-Hodgkin's lymphoma (NHL) involving the gastrointestinal (GI) tract and the clinical utility of modality despite of the known normal uptake of FDG in the GI tract. METHODS: Thirty-three patients with biopsy-proven gastrointestinal NHL who had undergone FDG-PET scan were inducted. All the patients were injected with 10-15 mCi FDG and scanned approximately 60 min later with a CTI/ Siemens HR (+) PET scanner. PET scans were reviewed and the maximum standard uptake value (SUVmax) of the lesions was measured before and after the treatment, if data were available and compared with histologic diagnoses. RESULTS: Twenty-five patients had a high-grade lymphoma and eight had a low-grade lymphoma. The stomach was the most common site of the involvement (20 patients). In high-grade lymphoma, PET showed focal nodular or diffuse hypermetabolic activity. The average SUVmax±SD was 11.58±5.83. After the therapy, the patients whose biopsies showed no evidence of lymphoma had a lower uptake without focal lesions. The SUVmax±SD decreased from 11.58±5.83 to 2.21± 0.78. In patients whose post-treatment biopsies showed lymphoma, the SUVmax±SD was 9.42±6.27. Low-grade follicular lymphomas of the colon and stomach showed diffuse hypermetabolic activity in the bowel wall (SUVmax 8.2 and 10.3, respectively). The SUVmax was 2.02-3.8 (mean 3.02) in the stomach lesions of patients with MALT lymphoma. CONCLUSION: 18F-FDG PET contributes to the diagnosis of high-grade gastrointestinal non-Hodgkin's lymphoma, even when there is the normal background FDG activity. Furthermore, the SUV plays a role in evaluating treatment response. Low-grade NHL demonstrates FDG uptake but at a lesser intensity than seen in high-grade NHL     

18F-fluorodeoxyglucose positron emission tomography/computed tomography in AIDS-related Burkitt lymphoma

This study aims to describe 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) findings in patients with AIDS-related Burkitt lymphoma, at various times of treatment, and to define its utility for a better patient management. We retrospectively studied 13 consecutive HIV-positive patients with Burkitt lymphoma who underwent one or more PET/CT. In 5 of 5 patients imaged before treatment, PET/CT confirmed all involved sites detected at conventional work-up and demonstrated additional sites in 4 of 5 patients. Lymph node involvement, which is known to be uncommon in endemic or sporadic Burkitt lymphoma, was present in 54% of patients. Additionally, in 3 patients, Burkitt lymphoma was predominantly located in parotid lymph nodes, which is also an unusual finding. A negative scan was encountered in 3 of 10 patients imaged during treatment and in 1 of 4 patients imaged after treatment completion and was always associated with lasting complete remission. Presence of residual area of uptake was related to both favorable and unfavorable outcome whether performed during treatment (5/7 and 2/7, respectively) or after (1/3 and 2/3, respectively). Areas of increased uptake could be observed in lung (4 cases) or esophagus (3 cases), and were clinically related to pneumonia or esophagitis. We recommend PET/CT for accurate initial staging of patients with AIDS-related Burkitt lymphoma. PET/CT is also useful to monitor treatment response, as regression of initial disease can be early observed. Furthermore, PET/CT appears to have prognostic value, as a negative scan was always associated with a favorable outcome.     

Incidental focal colorectal 18F-fluorodeoxyglucose uptake on positron emission tomography/computed tomography

AIM: To assess the clinical significance of incidental focal colorectal 18 F-fluorodeoxyglucose ( 18 F-FDG) uptake on 18 F-FDG-positron emission tomography/computed tomography (PET/CT). METHODS: The records of all the cases which had undergone colonoscopy after PET/CT within a two weeks interval were reviewed. Adenomas were considered advanced when they were villous, ≥ 10 mm in size, or had high-grade dysplasia. Colorectal cancers and advanced adenomas are collectively referred to as advanced colorectal neoplasms. Receiver-operating characteristic curve analysis was used to determine thesignificant predictive maximum standardized uptake value (SUVmax) cutoff value for advanced colorectal neoplasms and cancer. RESULTS: Ninety-five colorectal lesions matched the site of incidental focal colorectal 18 F-FDG uptake on PET/CT and 146 did not. Colonoscopy showed advanced colorectal neoplasms corresponding to the site of 18 F-FDG uptake in 49 of the 95 (51.5%) lesions with incidental uptake. Of the lesions without incidental uptake, only 6 of 146 (4.1%) had advanced colorectal neoplasms on colonoscopy, indicating a statistically significant difference between the two groups (P < 0.001). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of incidental focal 18 F-FDG uptake in identifying advanced colorectal neoplasms were 89.1%, 75.3%, 51.6%, 95.9%, and 78.4%, respectively. In detecting only CRC, these values were 89.2%, 69.6%, 34.7%, 97.3%, and 72.6%, respectively. The significant SUVmax cutoff value for advanced colorectal neoplasms (area under the curve 0.755, P < 0.001) was 4.35, with a sensitivity, specificity, PPV, NPV, and accuracy of 75.5%, 65.2%, 69.8%, 71.4% and 70.5%, respectively. For CRC, 5.05 was the significant SUVmax cutoff value (area under the curve 0.817, P < 0.001), with a sensitivity, specificity, PPV, NPV, and accuracy of 84.8%, 71.0%, 80.9%, 89.8%, and 75.8%, respectively. CONCLUSION: The presence of incidental focal colorectal 1     

Positron emission tomography/computed tomography with (18)F-fluorodeoxyglucose identifies tumor growth or thrombosis in the portal vein with hepatocellular carcinoma

Patients suffering from hepatocellular carcinoma (HCC) with tumor thrombus in the portal vein generally have a poor prognosis. Portal vein tumor thrombus must be distinguished from portal vein blood thrombus, and this identification plays a very important role in management of HCC. Conventional imaging modalities have limitations in discrimination of portal vein tumor thrombus. The application of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for discrimination between tumor extension and blood thrombus has been reported in few cases of HCC, while portal tumor thrombosis and portal vein clot identified by 18F-FDG PET/CT in HCC patients has not been reported so far. We present two HCC cases, one with portal vein tumor thrombus and one thrombosis who were identified with 18F-FDG PET/CT. This report illustrates the complimentary value of combining the morphological and functional imaging in achieving a correct diagnosis in such clinical situations.     

推进18F-FDG PET/CT显像在心血管炎症的临床应用

炎症是多种心血管疾病的主要致病因素或重要病理特征,对其进行精准评价具有重要的临床意义。18氟标记脱氧葡萄糖正电子发射型计算机断层扫描显像(18F-FDG PET/CT)作为功能性影像技术,能特异地显示炎症活性。近年来的研究表明,18F-FDG PET/CT在动脉粥样硬化、感染性心内膜炎、心脏结节病、急性心肌梗死和血管炎等疾病的诊断、鉴别诊断、治疗决策制定和预后评估等方面具有独特的价值。随着PET/CT在我国的加快普及和推广,有望在心血管炎症疾病的诊疗中发挥更大的作用。     

Diagnostic role of 18F-fluorodeoxyglucose positron emission tomography for follicular lymphoma with gastrointestinal involvement

AIM:To investigate the capacity for 18F-fluorodeoxyglucose(18F-FDG) positron emission tomography(PET) to evaluate patients with gastrointestinal lesions of follicular lymphoma.METHODS:This retrospective case series consisted of 41 patients with follicular lymphoma and gastrointestinal involvement who underwent 18F-FDG-PET and endoscopic evaluations at ten different institutions between November 1996 and October 2011.Data for endoscopic,radiological,and biological examinations performed were retrospectively reviewed from clinical records.A semi-quantitative analysis of 18F-FDG uptake was performed for each involved area by calculating the maximum standardized uptake value(SUVmax).Based on the positivity of 18F-FDG uptake in the gastrointestinal lesions analyzed,patients were subdivided into two groups.To identify potential predictive factors for 18F-FDG positivity,these two groups were compared with respect to gender,age at diagnosis of lymphoma,histopathological grade,pattern of follicular dendritic cells,mitotic rate,clinical stage,soluble interleukin-2 receptor levels detected by 18F-FDG-PET,lactate dehydrogenase(LDH) levels,hemoglobin levels,bone marrow involvement,detectability of gastrointestinal lesions by computed tomography(CT) scanning,and follicular lymphoma international prognostic index(FLIPI) risk.RESULTS:Involvement of follicular lymphoma in the stomach,duodenum,jejunum,ileum,cecum,colon,and rectum was identified in 1,34,6,3,2,3,and 6 patients,respectively.No patient had esophageal involvement.In total,19/41(46.3%) patients exhibited true-positive 18F-FDG uptake in the lesions present in their gastrointestinal tract.In contrast,false-negative 18F-FDG uptake was detected in 24 patients(58.5%),while false-positive 18F-FDG uptake was detected in 5 patients(12.2%).In the former case,2/19 patients had both 18F-FDG-positive lesions and 18F-FDGnegative lesions in the gastrointestinal tract.In patients with 18F-FDG avidity,the SUVmax value of the involved gastrointestinal tract ranged from 2.6 to 17.4(median:4.7).For the 18F-FDG-negative(n = 22) and-positive(n = 19) groups,there were no differences in the male to female ratios(10/12 vs 4/15,P = 0.186),patient age(63.6 ± 2.4 years vs 60.1 ± 2.6 years,P = 0.323),presence of histopathological grade 1 vs 2(20/2 and 17/2,P = 1.000),follicular dendritic cell pattern(duodenal/nodal:13/5 vs 10/3,P = 1.000),mitotic rate(low/partly high,14/1 vs 10/3,P = 0.311),clinical stage according to the Ann Arbor system(stages ⅠE and ⅡE/other,15/7 vs 15/4,P = 0.499),clinical stage according to the Lugano system(stages Ⅰ and Ⅱ-1/other,14/8 vs 14/5,P = 0.489),soluble interleukin-2 receptor levels(495 ± 78 vs 402 ± 83,P = 0.884),LDH levels(188 ± 7 vs 183 ± 8,P = 0.749),hemoglobin levels(13.5 ± 0.3 vs 12.8 ± 0.4,P = 0.197),bone marrow involvement(positive/negative,1/8 vs 1/10,P = 1.000),detectability by CT scanning(positive/negative,1/16 vs 4/13,P = 0.335),and FLIPI risk(low risk/other,16/6 vs 13/6,P = 0.763),respectively in each case.CONCLUSION:These findings indicate that it is not feasible to predict 18F-FDG-avidity.Therefore,18FFDG-PET scans represent a complementary modality for the detection of gastrointestinal involvements in follicular lymphoma patients,and surveillance of the entire gastrointestinal tract by endoscopic examinations is required.     

Advantages of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in detecting post cardiac surgery infections

The 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) offers an excellent negative predictive value. Consequently, it is a reliable tool for excluding an infectious phenomenon in case of negativity. In case of persistent fever of unknown origin after cardiac surgery and in combination with other bacteriological examinations and medical imaging, we can rely on FDG-PET/CT to confirm or eliminate deep infections and prosthetic endocarditis. For this reason, FDG-PET/CT should be considered among the examinations to be performed in case of suspected infection after cardiac surgery. We have reported the case of a 76-year-old man who presented with a fever of unknown origin and recurrent septic shocks after a biological Bentall procedure combined with left anterior descending (LAD) coronary artery revascularization by the left internal thoracic artery. We performed a FDG-PET/CT which showed external iliac vein and right common femoral vein hyperfixation with infiltration of adjacent soft tissues, highly suspected to be an infectious process.

Learning objective

The aim of this case report is to show that FDG-PET/CT, in combination with other bacteriological examinations and medical imaging, can be extremely helpful in detecting deep infectious sources, even during the early postoperative period.     

Evaluation of organ involvement in intravascular large B-cell lymphoma by 18F-fluorodeoxyglucose positron emission tomography

To evaluate the role of (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET) in intravascular large B-cell lymphoma (IVLBCL), we retrospectively analyzed four consecutive IVLBCL patients receiving FDG-PET before treatment between May 2006 and November 2007. Patients were two men and two women (median age 62 years, range 54-76 years). All patients received bone marrow biopsies and random skin biopsies and two of the four patients underwent renal biopsy for diagnosis. Accuracy of FDG-PET for the detection of organ involvements was analyzed by comparing results of pathological findings. Concordant results with respect to bone marrow involvement were accurately obtained for two patients. Skin and renal involvements were undetectable by FDG-PET regardless of positive pathological findings. One patient with a false-negative FDG-PET result showed fewer lymphoma cells in the bone marrow specimen than patients with concordant FDG-PET results. These results suggest false-negative results for some types of organ involvement. Careful interpretation of the results of FDG-PET in IVLBCL is thus required.     

Clinical role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography in post-operative follow up of gastric cancer： Initial results

AIM： To evaluate the clinical role of 18F-fluorodeo-xyglucose positron emission and computed tomography （18F-FDG PET/CT） in detection of gastric cancer recurrence after initial surgical resection. METHODS： In the period from January 2007 to May 2008, 23 patients who had previous surgical resection of histopathologically diagnosed gastric cancer underwent a total of 25 18F-FDG PET/CT scans as follow-up visits in our center. The standard of reference for tumor recurrence consisted of histopathologic confirmation or clinical follow-up information for at least 5 mo after PET/CT examinations. RESULTS： PET/CT was positive in 14 patients （61%） and negative in 9 （39%）. When correlated with final diagnosis, which was confirmed by histopathologic evidence of tumor recurrence in 8 of the 23 patients （35%） and by clinical follow-up in 15 （65%）, PET/CT was true positive in 12 patients, false positive in 2, true negative in 8 and false negative in 2. Overall, the accuracy of PET/CT was 82.6%, the negative predictive value （NPV） was 77.7%, and the positive predictive value （PPV） was 85.7%. The 2 false positive PET/CT findings were actually chronic inflammatory tissue lesions. For the two patients with false negativePET/CT, the f inal diagnosis was recurrence of mucinous adenocarcinoma in the anastomosis in one patient and abdominal wall metastasis in the other. Importantly, PET/CT revealed true-positive findings in 11 （47.8%） patients who had negative or no definite findings by CT. PET/CT revealed extra-abdominal metastases in 7 patients and additional esophageal carcinoma in one patient. Clinical treatment decisions were changed in 7 （30.4%） patients after introducing PET/CT into their conventional post-operative follow-up program. CONCLUSION： Whole body 18F-FDG PET/CT was highly effective in discriminating true recurrence in post-operative patients with gastric cancer and had important impacts on clinical decisions in a considerable portion of patients.     

18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) does not visualize follicular lymphoma of the duodenum

<p>18F-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) has been used as a potential tool for imaging nodal follicular lymphoma (FL) and extranodal spread. As primary intestinal FL is increasingly being recognized, we have performed a study to investigate the usefulness of 18F-FDG-PET for staging of extranodal FL within the gastrointestinal tract. In eight patients with a diagnosis of FL localized in the duodenum (six cases in stage I and one each in stages II and IV, respectively) whole body 18F-FDG-PET scans were performed. Seven patients with duodenal FL were rated WHO grade 1 and one had FL grade 3, while both patients with secondary spread had FL WHO grade 1. All patients were imaged before initiation of therapy. None of the patients with primary duodenal FL showed pathologically elevated 18F-FDG uptake. 18F-FDG-PET findings were not influenced by histological grade or proliferative activity of FL. These findings suggest that 18F-FDG-PET is not useful for clinical assessment of primary duodenal FL.     

18FDG-positron emission tomography/computed tomography (PET/CT) scanning in thyroid nodules with nondiagnostic cytology

Objective To assess the role of positron emission tomography/computed tomography (PET/CT) scans with ¹⁸FDG (¹⁸FDG‐PET/CT) in the evaluation of thyroid nodules with nondiagnostic cytology. Subjects and methods Eighty‐eight patients with a single euthyroid nodule and repeatedly nondiagnostic ultrasound‐guided fine‐needle cytology (US‐FNC) were enrolled in the present study. Nodules concentrating ¹⁸FDG were considered positive (i.e. suspicious for malignancy). Histological findings were obtained after surgery in all patients. Results None of 41 patients with negative ¹⁸FDG‐PET/CT scan had a final histological diagnosis of malignancy (i.e. no false‐negative results). Twenty‐nine patients with final histological diagnosis of thyroid cancer had positive ¹⁸FDG‐PET/CT scan. Eighteen patients with final histological diagnosis of benign lesions (including four with follicular adenomas) also had positive ¹⁸FDG‐PET/CT scans. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were 100%, 69%, 79%, 62% and 100%, respectively. Conclusions A negative ¹⁸FDG‐PET/CT scan accurately excludes malignancy in thyroid nodules with non‐diagnostic US‐FNC procedures. Histology is still necessary to distinguish benign from malignant disease in ¹⁸FDG‐PET/CT‐positive nodules, but unnecessary surgery could have been reduced from 88 to 41 cases (46%) in our series.     

Attenuation-corrected 99mTc-tetrofosmin single-photon emission computed tomography in the detection of viable myocardium: comparison with positron emission tomography using 18F-fluorodeoxyglucose

Objectives. The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (^99mTc)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET).Background. The role of ^99mTc-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images.Methods. Twenty-four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting ^99mTc-tetrofosmin SPECT and FDG PET imaging. Both AC and non–attenuation-corrected (NC) SPECT images were generated.Results. Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between ^99mTc-tetrofosmin and FDG on the patient basis increased from 79.8% ± 14.0% (mean ± SD) on the NC images to 90.8% ± 10.6% on the AC images (p = 0.002). The percentage of ^99mTc-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8% ± 15.2% on the NC images to 9.7% ± 12.6% on the AC images (p = 0.01). Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior-septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region.Conclusions. The results indicate that AC ^99mTc-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior-septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction.     

Feasibility of assessing regional myocardial uptake of 18F-fluorodeoxyglucose using single photon emission computed tomography

Differentiation between viable myocardium and scar tissue insegments with abnormal contraction has important consequencesin the clinical management of patients with coronary arterydisease. Positron emission tomography (PET) can identify viabletissue using ¹⁸F-fluorodeoxyglucose (FDG). However, applicationof PET for daily routine is limited. In this study, FDG uptakewas visualized with single photon emission computed tomography(SPECT) and compared with regional perfusion assessed with thallium-201(²⁰¹Tl) SPECT. The scintigraphic findings were related to regionalregional wall motion determined with two-dimensional echocardiography.Patients (n = 9) with wall motion abnormalities underwent FDGSPECT and resting ²⁰¹Tl SPECT. To control the metabolic statuspatients were studied with a hyperinsulinaemic euglycemic clampduring FDG SPECT. Analysis of reconstructed data was performedvisually and semiquantitatively using circumferential profiles.High-quality images were obtained. Eight ²⁰¹Tl defects showedconcordantly decreased FDG uptake (metabolism-perfusion matches)indicating scarred tissue, whereas six regions of hypoperfusiondemonstrated a relatively increased FDG uptake (mismatches),suggesting viable myocardium. Semiquantitative analysis confirmedvisual findings. Mean ²⁰¹Tl and FDG activities were not significantlydifferent in matching defects. In mismatches the mean FDG activitywas 81 ± 11% vs 64 ± 9% mean ²⁰¹Tl activity (P<0.0001).In four of six segments with increased FDG uptake, two-dimensionalecho revealed hypokinesia. Seven of eight regions with a matchingdefect in contrast were akinetic. Thus, in the areas with amismatch contractility was preserved. We conclude that FDG uptakecan be visualized with SPECT. Furthermore, our preliminary observationssuggest that this approach can identify viable tissue.