Fluorodeoxyglucose F18 Positron Emission Tomography Coupled With Computed Tomography in Suspected Acute Renal Allograft Rejection

Management of kidney transplant recipients (KTRs) with suspected acute rejection (AR) ultimately relies on kidney biopsy; however, noninvasive tests predicting nonrejection would help avoid unnecessary biopsy. AR involves recruitment of leukocytes avid for fluorodeoxyglucose F¹⁸ (¹⁸F‐FDG), thus ¹⁸F‐FDG positron emission tomography (PET) coupled with computed tomography (CT) may noninvasively distinguish nonrejection from AR. From January 2013 to February 2015, we prospectively performed 32 ¹⁸F‐FDG PET/CT scans in 31 adult KTRs with suspected AR who underwent transplant biopsy. Biopsies were categorized into four groups: normal (n = 8), borderline (n = 10), AR (n = 8), or other (n = 6, including 3 with polyoma BK nephropathy). Estimated GFR was comparable in all groups. PET/CT was performed 201 ± 18 minutes after administration of 3.2 ± 0.2 MBq/kg of ¹⁸F‐FDG, before any immunosuppression change. Mean standard uptake values (SUVs) of both upper and lower renal poles were measured. Mean SUVs reached 1.5 ± 0.2, 1.6 ± 0.3, 2.9 ± 0.8, and 2.2 ± 1.2 for the normal, borderline, AR, and other groups, respectively. One‐way analysis of variance demonstrated a significant difference of mean SUVs among groups. A positive correlation between mean SUV and acute composite Banff score was found, with r² = 0.49. The area under the receiver operating characteristic curve was 0.93, with 100% sensitivity and 50% specificity using a mean SUV threshold of 1.6. In conclusion, ¹⁸F‐FDG PET/CT may help noninvasively prevent avoidable transplant biopsies in KTRs with suspected AR.     

18F-脱氧葡萄糖正电子发射体层显像检查在肺结核患者中的应用

目的探讨18F-脱氧葡萄糖正电子发射体层显像(18F-FDG-PET)检查在肺结核患者中的应用价值。方法回顾性分析53例肺结核患者的18F-FDG-PET检查结果,采用目测法判读,半定量分析法检测肺部结核显影病灶的最大标准摄取值(SUVmax)和平均标准摄取值(SUVmean)以及相应正常肺组织标准摄取值(SUVlung)。结果36例肺结核结节在18F-FDG-PET检查中显影,目测法判断为活动性结核,半定量分析法观察结核病变的SUVmax(2.77±1.20)和SUVmean(2.15±0.86)分别高于SUVlung(0.41±0.09,Z=-5.232,P<0.01;Z=-5.232,P<0.01)。SUVmax和SUVmean与病变大小(Dmax、Dmin)、SUVlung、患者年龄、血糖水平均无明显的相关性(P>0.05)。17例无干酪样坏死的陈旧性结核纤维化和钙化病灶未显影。结论18F-FDG-PET检查可以有效地判断肺结核结节是否属活动期、确定结核累及的范围和有助于制定治疗方案。     

18F-脱氧葡萄糖正电子发射体层显像在食管癌患者中的应用

目的探讨^18F-脱氧葡萄糖正电子发射体层显像（^18F-FDG—PET）检查在食管癌患者诊断、治疗中的应用价值。方法1999年10月～2005年12月，对52例食管癌患者行全身^18F-FDG—PET检查，其中15例在检查前未经任何治疗，37例为综合治疗后复查。采用目测法结合半定量分析法判读^18F-FDG—PET检查结果，并与病理检查和随访结果进行对比。结果在15例行^18F-FDG—PET检查前未经任何治疗的食管癌患者中，11例患者（T2～T4）原发肿瘤显影，4例T1原发肿瘤未显影；^18F-FDG—PET检查定性诊断的灵敏度为73．3％（11／15）。8例手术治疗的患者切除纵隔和腹腔直径〉1cm的淋巴结16处，术前6处经^18F-FDG—PET检查定性为恶性，其中5处为转移淋巴结，1处为淋巴结结核；7例患者经^18F-FDG—PET检查发现有远处器官转移，不适合手术治疗。37例经综合治疗后患者复查^18F-FDG—PET，发现34例有肿瘤复发和／或转移。结论^18F-FDG—PET检查对食管癌原发肿瘤和局部淋巴结转移的定性诊断价值有限，但对发现远处器官转移和判断治疗效果有较大的帮助，^18F-FDG—PET检查需结合其他辅助检查才能发挥其优势。     

Preoperative Positron Emission Tomography with Fluorine-18-Fluorodeoxyglucose is Predictive of Prognosis in Patients with Hepatocellular Carcinoma after Resection

Background: Hepatocellular carcinomas (HCCs) accumulate fluorine-18 fluorodeoxyglucose (FDG) to various degrees. The standardized uptake values (SUVs) of FDG-positron emission tomography (PET) in high-grade HCCs are significantly higher than those in low-grade HCCs. Aim: The aim of this study was to evaluate the possible usefulness of FDG-PET in predicting the prognosis of HCC patients after resection. We analyzed the relationship between the tumor to non-tumor SUV ratios (SUV ratio) and surgical outcome in 31 patients. Results: Of the 31 cases of HCC studied, seven (23%) exhibited SUV ratios greater than 2, as the cutoff value. The percentage of patients with poorly differentiated HCC was greater in the higher SUV ratio group (SUV ratio >2) than in the lower SUV ratio group (SUV ratio <2) (57 vs. 32%). The overall survival was significantly longer in the lower SUV ratio group than in the higher SUV ratio group (5-year-survival rate: 63 vs. 29% P = 0.006) (median survival time: 2310 vs.182 days). Conclusion: The SUV ratio was related significantly to disease-related death as well as other predictive factors, including the number of tumors, the size, stage, and involvement of vessels, and the involvement of the capsule. Consequently, we conclude that the SUV ratio provides information of prognostic relevance in patients with HCC before surgery.     

Imaging of Site Specific Bone Turnover in Osteoporosis Using Positron Emission Tomography

The functional imaging technique of dynamic fluorine-18 labeled sodium fluoride positron emission tomography (¹⁸F-NaF PET) allows the quantitative assessment of regional bone formation by measuring the plasma clearance of fluoride to bone at any site in the skeleton. ¹⁸F-NaF PET provides a novel and noninvasive method of studying site-specific bone formation at the hip and spine, as well as areas of pure cortical or trabecular bone. The technique complements conventional measurements of bone turnover using biochemical markers and bone biopsy as a tool to investigate new treatments for osteoporosis, and holds promise of a future role as an early biomarker of treatment efficacy in clinical trials. This article reviews methods of acquiring and analyzing ¹⁸F-NaF PET scan data, and outlines a simplified approach that uses 5-minute static PET scan images combined with venous blood samples to estimate ¹⁸F-NaF plasma clearance at multiple sites in the skeleton with a single injection of tracer.     

F-18 Fluoride Positron Emission Tomography of the Hip for Osteonecrosis

Osteonecrosis (ON) of the femoral head continues to be a devastating disorder for young patients. We evaluated the F-18 fluoride positron emission tomography (PET) imaging modality for use in detection of the bone involved in ON of the hip. We retrospectively reviewed the records of 60 consecutive patients diagnosed with ON and interviewed all by phone. Eleven patients (17 hips) of those interviewed agreed to participate in the study. We classified the ON using the University of Pennsylvania classification system and compared each patient's plain AP bone scan, single photon emission 3-D computed tomography, and MRI. ON was associated with HIV, alcohol, steroid use, and polycythemia vera in this group. Nine of 17 hips (8 patients) had acetabular increased uptake when using the F-18 fluoride PET scans that were not seen on MRI, single photon emission computed tomography, or bone scans. These data suggest earlier acetabular changes in osteonecrosis may exist that traditional imaging modalities do not reveal.     

[11C]Metahydroxyephedrine and [18F]Fluorodeoxyglucose Positron Emission Tomography Improve Clinical Decision Making in Suspected Pheochromocytoma

Background Pheochromocytomas are rare tumors of chromaffin cells for which the optimal management is surgical resection. Precise diagnosis and localization may be elusive. We evaluated whether positron emission tomography (PET) scanning with the combination of [¹⁸F]fluorodeoxyglucose (FDG) and the norepinephrine analogue [¹¹C]metahydroxyephedrine (mHED) would allow more exact diagnosis and localization. Methods Fourteen patients with suspected pheochromocytoma were evaluated by anatomical imaging (computed tomography or magnetic resonance imaging) and [¹³¹I]metaiodobenzylguanidine (MIBG) planar imaging. PET imaging was performed by using mHED with dynamic adrenal imaging, followed by a torso survey and FDG with a torso survey. Images were evaluated qualitatively by an experienced observer. Results Eight patients had pathology-confirmed pheochromocytoma. Of the other six, two patients had normal adrenal tissue at adrenalectomy, and the other four had subsequent clinical courses inconsistent with a diagnosis of pheochromocytoma. In four of eight patients with pheochromocytoma, MIBG failed to detect one or more sites of pathology-confirmed disease. The mHED-PET detected all sites of confirmed disease, whereas FDG-PET detected all sites of adrenal and abdominal disease, but not bone metastases, in one patient. MIBG and FDG-PET results were all negative in the six patients without pheochromocytoma. One patient with adrenal medullary hyperplasia had a positive mHED-PET scan. PET scanning aided the decision not to operate in three of six patients. The resolution of PET functional imaging was superior to that of MIBG. Conclusions PET scanning for pheochromocytoma offers improved quality and resolution over current diagnostic approaches. PET may significantly influence the clinical management of patients with a suspicion of these tumors and warrants further investigation. Presented at the 58th Annual Meeting of the Society of Surgical Oncology, Atlanta, Georgia, March 2005.     

18-Fluorodeoxyglucose Positron Emission Tomography Predicts Recurrence in Resected Pancreatic Ductal Adenocarcinoma

Background

We aimed to determine whether treatment should be stratified according to 18-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) maximum standardized uptake values (SUV_max) in pancreatic ductal adenocarcinoma.

Methods

Patients who underwent preoperative 18F-FDG PET/CT between 2006 and 2014 (n = 138) were stratified into high (≥ 4.85) and low (< 4.85) PET groups. The clinicopathological characteristics and prognostic outcomes were analyzed retrospectively.

Results

The primary tumor SUV_max was positively correlated with preoperative CA19-9 levels (P < 0.001). The high PET group failed to achieve postoperative CA19-9 normalization (P = 0.014). Disease-specific (P < 0.001), recurrence-free (P < 0.001), liver recurrence-free (P < 0.001), and peritoneal recurrence-free (P = 0.020) survivals were significantly shorter in the high PET group. The primary tumor SUV_max was an independent predictive risk factor for liver metastasis (hazard ratio 3.46, 95% confidence interval 1.61–7.87; P = 0.001) and peritoneal recurrence (hazard ratio 3.36, 95% confidence interval 1.18–10.89; P = 0.023).

Conclusions

Surgical resection failed to achieve CA19-9 normalization in the high PET group and distant recurrence was frequent. This suggests the potential for residual cancer at distant sites, even after curative resection. Stronger preoperative systemic chemotherapy is preferred for the high PET group patients.

     

Positron Emission Tomography Affects Surgical Management in Recurrent Colorectal Cancer Patients

Background: We determined the effect of positron emission tomography (PET) on surgical decision-making in patients with metastatic or recurrent colorectal cancer.Methods: A total of 114 patients with advanced colorectal cancer were imaged with computed tomography (CT) and PET scans. The PET and CT scans were independently interpreted before surgery and recorded.Results: Forty-two of the 114 patients had resectable disease on the basis of CT. PET altered therapy in 17 (40%) of these 42 patients on the basis of the following results: extrahepatic disease (n = 9), bilobar involvement (n = 3), thoracic involvement (n = 5), retroperitoneal lymphadenopathy (n = 2), bone involvement (n = 1), and supraclavicular disease (n = 1). In 25 patients with liver metastases only, PET found additional disease in 18 (72%), extrahepatic disease in 11, chest disease in 13, retroperitoneal lymphadenopathy in 4, and bone disease in 3. In five patients, both scans underestimated small-volume peritoneal metastases discovered at laparotomy.Conclusions: PET altered therapy in 40% of patients. In patients with isolated liver involvement, 72% had more extensive disease that precluded surgical resection. PET scans should be used in the management of patients with recurrent colorectal cancer who are being considered for potentially curative surgery.     

Value of 18-Fluorodeoxyglucose Positron Emission Tomography in the Management of Patients With Cystic Tumors of the Pancreas

OBJECTIVE: To assess the reliability of 18-fluorodeoxyglucose positron emission tomography (18-FDG PET) in distinguishing benign from malignant cystic lesions of the pancreas. SUMMARY BACKGROUND DATA: The preoperative differential diagnosis of cystic lesions of the pancreas remains difficult: the most important point is to identify malignant or premalignant cysts that require resection. 18-FDG PET is a new imaging procedure based on the increased glucose metabolism by tumor cells and has been proposed for the diagnosis and staging of pancreatic cancer. METHODS: During a 4-year period, 56 patients with a suspected cystic tumor of the pancreas underwent 18-FDG PET in addition to computed tomography scanning, serum CA 19-9 assay, and in some instances magnetic resonance imaging or endoscopic retrograde cholangiopancreatography. The 18-FDG PET was analyzed visually and semiquantitatively using the standard uptake value. The accuracy of 18-FDG PET and computed tomography was determined for preoperative diagnosis of a malignant cyst. RESULTS: Seventeen patients had malignant tumors. Sixteen patients (94%) showed 18-FDG uptake with a standard uptake value of 2.6 to 12.0. Twelve patients (70%) were correctly identified as having malignancy by computed tomography, CA 19-9 assay, or both. Thirty-nine patients had benign tumors: only one mucinous cystadenoma showed increased 18-FDG uptake (standard uptake value 2.6). Five patients with benign cysts showed computed tomography findings of malignancy. Sensitivity, specificity, and positive and negative predictive values for 18-FDG PET and computed tomography scanning in detecting malignant tumors were 94%, 97%, 94%, and 97% and 65%, 87%, 69%, and 85%, respectively. CONCLUSIONS: 18-FDG PET is more accurate than computed tomography in identifying malignant pancreatic cystic lesions and should be used, in combination with computed tomography and tumor markers assay, in the preoperative evaluation of patients with pancreatic cystic lesions. A positive result on 18-FDG PET strongly suggests malignancy and, therefore, a need for resection; a negative result shows a benign tumor that may be treated with limited resection or, in selected high-risk patients, with biopsy, follow-up, or both.     

Positron Emission Tomography Study of Regional Cerebral Metabolism during General Anesthesia with Xenon in Humans

Background: The precise mechanism by which the gaseous anesthetic xenon exerts its effects in the human brain remains unknown. Xenon has only negligible effects on inhibitory [gamma]-aminobutyric acid receptors, one of the putative molecular targets for most general anesthetics. Instead, xenon has been suggested to induce anesthesia by inhibiting excitatory glutamatergic signaling. Therefore, the authors hypothesized that xenon, similar to ketamine and nitrous oxide, increases global and regional cerebral metabolism in humans.

Methods: The regional cerebral metabolic rate of glucose (rcMRGlu) was sequentially assessed in two groups of six volunteers each, using 18F-fluorodeoxyglucose as tracer. In the xenon group, rcMRGlu was determined at baseline and during general anesthesia induced with propofol and maintained with 1 minimum alveolar concentration xenon. In the control group, rcMRGlu was measured using the identical study protocol but without administration of xenon. rcMRGlu was assessed after the plasma concentration of propofol had decreased to subanesthetic levels (< 1.0 [mu]g/ml). rcMRGlu was quantified in 10 cerebral volumes of interest. In addition, voxel-wise changes in rcMRGlu were analyzed using statistical parametric mapping.

Results: Xenon reduced whole-brain metabolic rate of glucose by 26 +/- 7% (from 43 +/- 5 [mu]mol [middle dot] 100 g-1 [middle dot] min-1 to 31 +/- 3 [mu]mol [middle dot] 100 g-1 [middle dot] min-1; P < 0.005) and significantly decreased rcMRGlu in all volumes of interest compared with the control group receiving propofol only. Voxel-based analysis revealed metabolic depression within the orbitofrontal, frontomesial, temporomesial, occipital, dorsolateral frontal, and lateral temporal cortices and thalami. No increases in rcMRGlu were detected during xenon anesthesia.     

Positron Emission Tomography Study of Regional Cerebral Metabolism in Humans during Isoflurane Anesthesia

Background: Although the anesthetic effects of the intravenous anesthetic agent propofol have been studied in the living human brain using brain imaging technology, the nature of the anesthetic state evident in the human brain during inhalational anesthesia remains unknown. To examine this issue, the authors studied the effects of isoflurane anesthesia on human cerebral glucose metabolism using positron emission tomography (PET).

Methods: Five volunteers each underwent two PET scans; one scan assessed awake-baseline metabolism and the other scan assessed metabolism during isoflurane anesthesia titrated to the point of unresponsiveness (means +/- SD; expired = 0.5 +/- 0.1%). Scans were obtained with a GE2048 scanner (4.5-mm resolution-FWHM) using the18 fluorodeoxyglucose technique.

Results: Awake whole-brain glucose metabolism averaged 6.9 +/- 1.5 mg [center dot] 100 g sup -1 [center dot] min sup -1 (means +/- SD). Isoflurane reduced whole-brain metabolism 46 +/- 11% to 3.6 +/- 0.3 mg [center dot] 100 g sup -1 [center dot] min sup -1 (P less or equal to 0.005). Regional metabolism decreased fairly uniformly throughout the brain, and no evidence of any regional metabolic increases were found in any brain region for any participant. A region-of-interest analysis showed that the pattern of regional metabolism evident during isoflurane anesthesia was not significantly different from that seen when participants were awake.     

Positron Emission Tomography Detection of Distant Metastatic or Synchronous Disease in Patients with Locally Advanced Rectal Cancer Receiving Preoperative Chemoradiation

Background Patients with locally advanced rectal cancer may present with synchronous distant metastases. Choice of optimal treatment—neoadjuvant chemoradiation versus systemic chemotherapy alone—depends on accurate assessment of distant disease. We prospectively evaluated the ability of [¹⁸F]fluorodeoxyglucose ([¹⁸F]FDG) positron emission tomography (PET) to detect distant disease in patients with locally advanced rectal cancer who were otherwise eligible for combined modality therapy (CMT). Methods Ninety-three patients with locally advanced rectal cancer underwent whole-body [¹⁸F]FDG PET scanning 2–3 weeks before starting CMT. Sites other than the rectum, mesorectum, or the area along the inferior mesenteric artery were considered distant and were divided into nine groups: neck, lung, mediastinal lymph node (LN), abdomen, liver, colon, pelvis, peripheral LN, and soft tissue. Two nuclear medicine physicians blinded to clinical information used PET images and a five-point scale (0–4) to determine certainty of disease. A score greater than 3 was considered malignant. Confirmation was based on tissue diagnosis, surgical exploration, and subsequent imaging. Results At a median follow-up of 34 months, the overall accuracy, sensitivity, and specificity of PET in detecting distant disease were 93.7%, 77.8%, and 98.7% respectively. Greatest accuracy was demonstrated in detection of liver (accuracy = 99.9%, sensitivity = 100%, specificity = 98.8%) and lung (accuracy = 99.9%, sensitivity = 80%, specificity = 100%) disease; PET detected 11/12 confirmed malignant sites in liver and lung. A total of 10 patients were confirmed to have M1 stage disease. All 10 were correctly staged by pre-CMT PET; abdominopelvic computed tomography (CT) scans accurately detected nine of them. Conclusion Baseline PET in patients with locally advanced rectal cancer reliably detects metastatic disease in liver and lung. PET may play a significant role in defining extent of distant disease in selected cases, thus impacting the choice of neoadjuvant therapy. An erratum to this article can be found at     

Preoperative Evaluation of Pancreatic Masses with Positron Emission Tomography Using 18F-fluorodeoxyglucose: Diagnostic Limitations

Identification of pancreatic cancer in patients presenting with an enlarged pancreatic mass is a major diagnostic problem. Positron emission tomography (PET) using the radiolabeled glucose analogue ¹⁸F-fluorodeoxyglucose (FDG) has been suggested to provide excellent accuracy for noninvasive determination of suspicious pancreatic masses. We conducted a prospective study to verify these results. Forty-two patients admitted for pancreatic surgery underwent PET scanning. Image analysis was based on visual film evaluation and quantification of regional tracer uptake. PET imaging was visually analyzed by three observers blinded for the results of other diagnostic tests; they qualitatively graded the scans using a five-point scale (I = low to V = high) for the presence and intensity of focal FDG uptake. Diagnosis was proven by histology (n= 38) or follow-up (n= 4). Furthermore, the results of PET were compared with helical computed tomography (CT) and conventional ultrasonography (US), done during the routine diagnostic workup before pancreatic cancer surgery. Regarding only the results with scores of IV and V as positive for representing definite malignancy yielded a sensitivity of 71% and a specificity of 64% for film reading. Quantification of regional tracer uptake contributed no significant diagnostic advantage for differentiation between benign and malignant tumors. Helical CT revealed a sensitivity of 74% and a specificity of 45.5% and abdominal US 56% and 50%, respectively. We concluded that PET imaging provides only fair diagnostic accuracy (69%) for characterizing enlarged pancreatic masses. PET does not allow exclusion of malignant tumors. In doubtful cases, the method must be combined with other imaging modalities, such as helical CT. The results indicate that the number of invasive procedures is not significantly reduced by PET imaging.     

Impact of 18-Fluorodeoxyglucose Positron Emission Tomography on the Management of Pancreatic Cancer

Background  

We compared the usefulness of positron emission tomography with the glucose analogue 2-deoxy-2-[18F]-fluoro-d-glucose (FDG-PET) and multidetector-row computed tomography (MD-CT) in diagnosing pancreatic cancer and in determining the patients’ suitability for surgery.