Whole-Body [18F]FDG PET in the Management of Metastatic Brain Tumours

Summary Background To determine its roles in the diagnosis and the systemic evaluation of metastatic brain tumours, whole-body positron emission tomography (PET) using [¹⁸F]FDG was performed in 20 consecutive patients. Methods  All patients were thought to be suffering or needing to be differentiated from metastatic brain tumours. Nine patients had multiple brain lesions; six were older and showed a rim-enhancing lesion with surrounding oedema; seven had homogeneously enhancing periventricular lesion(s) on computed tomography (CT) and/or magnetic resonance (MR) imaging, thought to be central nervous system lymphomas. Two patients had skull mass(es) and two patients had a solid mass suspected to be, respectively, a haemorrhagic metastasis and a metastatic malignant melanoma. All of them received whole-body [¹⁸F]FDG PET and conventional systemic work-up for metastasis in order to compare the results of the two methods. Results  Metastatic brain tumours were diagnosed on whole-body [¹⁸F]FDG PET in eleven patients who had extracranial and intracranial hypermetabolic lesions. In nine of these, a conventional work-up also detected primary lesions which on whole-body [¹⁸F]FDG PET were seen to be hypermetabolic foci. Systemic lymph node metastases were detected by whole-body [¹⁸F]FDG PET only in two patients and histological diagnosis was possible by biopsy of lymph nodes rather than of brain lesions. In the remaining nine patients who had only intracranial hypermetabolic foci, histological diagnosis was made by craniotomy or stereotactic biopsy. It was confirmed that seven of nine patients were suffering from a primary brain tumour and two from metastatic carcinoma. None of the nine showed evidence of systemic cancer on conventional work-up. Histological diagnoses of the primary brain tumours were four cases of primary central nervous system lymphoma and one each of multifocal glioblastoma, Ewing's sarcoma, and cavernous angioma.  Patients felt no discomfort during the whole-body [¹⁸F]FDG PET procedure and there were no complications. The false negative rate in [¹⁸F]FDG PET and in conventional work-up was 15.4% and 30.7% respectively. There were no false positives on either [¹⁸F]FDG PET or conventional work-up. Conclusion  It is suggested that whole-body [¹⁸F]FDG PET is a safe, reliable, and convenient method for the diagnosis and systemic evaluation of patients thought to be suffering or needing to be differentiated from a metastatic brain tumour.     

Evaluation of 18F-2-deoxy-2-fluoro-<Emphasis Type="SmallCaps">d</Emphasis>-glucose Positron Emission Tomography for Gastric Cancer

Positron emission tomography (PET) with ¹⁸F-2-deoxy-2-fluoro-d-glucose (FDG) has been investigated as a means of detecting certain primary tumors and their metastatic disease in recent years. The aim of this study was to compare the performance of FDG-PET and operative assessment with formal pathologic staging. Altogether, 85 patients had undergone surgical treatment for gastric cancer with curative intent, with FDG-PET preoperatively. The results using FDG-PET were compared with those using computed tomography (CT); they were also correlated with the pathologic findings. For quantitative analysis, the regional tumor uptake was measured by the standard uptake value (SUV) using a region of interest technique. Using FDG-PET, the primary tumor was visualized in 75.2% of patients. A comparison of the FDG uptake and the clinicopathologic findings showed that there was a significant association between FDG uptake and the depth of invasion, the size of the tumor, and lymph node metastasis. FDG-PET scans had less accuracy for diagnosing locoregional lymph nodes than CT because of a significant lack of sensitivity (23.3% vs. 65.0%). The survival rate for patients with high FDG uptake (SUV > 4) was significantly lower than that for those with low FDG uptake (SUV < 4) (p < 0.05). FDG-PET was successful in detecting the primary gastric cancer lesion but not for finding early-stage gastric cancers. Detection of nodal metastasis also was not possible by FDG-PET. However, FDG-PET appears to provide important additional information concerning the aggressiveness of the tumor and the prognosis in patients with gastric cancer.     

The distinctive role of positron emission tomography/computed tomography in breast carcinoma with brown adipose tissue 2-fluoro-2-deoxy-d-glucose uptake

The diagnostic power of an integrated positron emission tomography/computed tomography (PET/CT) system for whole-body 2-fluoro-2-deoxy-d-glucose (FDG) imaging is clearly demonstrated in this case report. The precise anatomic localization of FDG uptake with CT in a PET/CT scan of a patient with known breast carcinoma helped identify a contralateral breast tumor with axillary lymph node metastasis despite the presence of extensive physiologic brown fat FDG uptake. Accordingly, the patient received appropriate surgical management and pathologic confirmation of the disease.     

Positron-emission tomography with 18F-2-fluoro-2-deoxy-D-glucose (18FDG-PET) in the diagnosis of retroperitoneal lymph-node metastases from testicular tumors

Summary In 1991, this prospectively designed study was started to assess the potentials of positron emission tomography with ¹⁸FDG in the diagnostic workup for the detection of lymph node metastases in testicular cancer, since there were no data available concerning this subject at this time. In 54 patients (27 patients with pure seminoma, 27 patients with non-seminomatous tumors) ¹⁸FDG-PET results were compared with the findings obtained with abdominal computed tomography, serum level of tumor markers (AFP, β -HCG), and the histopathological findings after primary or post-chemotherapy retroperitoneal lymph node dissection. In 21 patients with pure seminoma (clinical stage I according to the Lugano classification) ¹⁸FDG-PET results were identical with those of the abdominal computed tomography, so PET does not add relevant informations in this group of patients. In 7 patients presenting with non-seminomatous testicular cancer (stage I), PET was not able to detect the existing micrometastases in 4 patients. In 1/7 case PET examination showed a suspicious focal lesion, this lymph node had 2 micrometastases within inflammatory changes. In 1/7 patient ¹⁸FDG-PET definitely revealed metastatic lesions, while the CT scans where judged to be unobtrusive and tumor marker levels were within the normal range. In the 4 patients with pure seminomas stage II B and II C (N = 6), that have undergone retroperitoneal lymph node dissection following chemotherapy, ¹⁸FDG-PET correctly predicted absence of tumor in 3 out of these 4, and in 1/4 patient the benign nature of a persistent large tumor after two cycles of polychemotherapy was correctly identified wich eventually turned out to be a ganglioneuroma. This lesion falsely was classified as malignant tumor with abdominal computed tomography, and in 2/4 patients post-chemotherapy residual retroperitoneal lesions in the CT scans could not be assessed exactly whether or not malignant tumor was present. In 20 patients presenting with non-seminomatous testicular cancer (stage II and III) ¹⁸FDG-PET was able to demonstrate therapeutic effects of chemotherapy by showing decreasing tracer activity in those regions, that had hypermetabolic foci prior to chemotherapy. It became evident in testicular cancer that there is a single entity which is not characterized by increased glucose metabolism, the mature teratoma. In lesions detected by abdominal computed tomography which do not present increased ¹⁸FDG uptake, mature teratoma as well as scar/necrosis or rare other tumors with normal glucose metabolism can be supposed, but additional characteristics based on different ¹⁸FDG uptake were not observed. In 1/20 case post-chemotherapy PET scan detected a hypermetabolic lesion, which was suspicious for metastatic spread, but in the histopathological examination this lesion was identified as inflammatory tissue reaction. Based on the data reported here in ¹⁸FDG-PET cannot be considered a standard diagnostic tool in the staging examinations in testicular cancer. It is of clinical relevance in patients who present residual tumor after chemotherapy. In this situation ¹⁸FDG-PET is helpful in deciding whether or not a residual mass post-chemotherapy contains active tumor. ¹⁸FDG-PET can not replace retroperitoneal lymph node dissection for staging purposes.      

18-Fluorodeoxyglucose-Positron Emission Tomography <Emphasis Type="Bold">in Inflammatory Breast Cancer</Emphasis>

Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer. It can be diagnosed based on a clinical or pathologic basis. We evaluated the usefulness of ¹⁸F-fluorodeoxyglucose-positron emission tomography (FDG-PET) scans for diagnosing and staging IBC. We retrospectively reviewed the medical records of seven consecutive patients with IBC who underwent FDG-PET scanning for the initial staging. Four patients had follow-up PET scans after chemotherapy. All seven patients presented with diffuse breast enlargement, redness, and peau dorange for 1 to 5 months duration. In addition, four patients had a palpable breast mass, and three had axillary lymph node enlargement. Mammography showed diffuse, increased parenchymal density and skin thickening in 85% and parenchymal distortion in 43%. There was no evidence of distant metastasis on computed tomography of the chest or abdomen. Pathologic examination of breast biopsy specimens showed infiltrating ductal carcinoma in six patients, and one had lobular carcinoma. All patients had prechemotherapy whole-body PET scans that showed diffuse FDG uptake in the breast with superimposed intense foci in the primary tumor. Furthermore, there was skin enhancement in 100%, axillary lymph node in 85%, and skeletal metastases in 14% of the patients, confirmed by bone scintigraphy. Postchemotherapy FDG-PET scans performed in four patients showed response in the primary tumor, axillary lymph nodes, and skeletal metastases. The FDG-PET scan is thus useful for displaying the pattern of FDG breast uptake that reflects the extent of the pathologic involvement in IBC (i.e., diffuse breast involvement and dermal lymphatic spread). It can also detect the presence of lymph node and skeletal metastases, demarcating the extent of the disease locally as well as distally.     

The application of positron emission tomographic imaging with fluorodeoxyglucose to the evaluation of breast disease.

Positron emission tomography (PET) is a computer-aided tomographic imaging technique that uses positron-emitting compounds to trace biochemical processes of tissue, and construct images based on them. The authors applied a whole-body PET imaging technique to patients with breast masses or mammographic abnormalities using the isotope 2-[F-18]-fluoro-2-deoxy-D-glucose (FDG), in a clinical trial to evaluate the feasibility of using PET to identify primary breast cancer, axillary lymph node involvement, and systemic metastases, before surgical resection. Fourteen patients have been entered on this study, 10 of whom proved to have breast cancer. Positron emission tomography correctly predicted the nature of 12 of the 14 primary breast lesions, and correctly determined the lymph node status of 11 of the 14 patients. The authors conclude that PET with FDG has potential as a diagnostic modality for detection of primary breast cancer, particularly in the patient with radiodense breasts by conventional mammography, and that it has potential for the preoperative identification of axillary lymph node metastases.     

Detection of incidental colorectal tumours with 18F‐labelled 2‐fluoro‐2‐deoxyglucose positron emission tomography/computed tomography scans: results of a prospective study

Aim This study assessed the clinical significance of incidental colorectal 2‐fluoro‐2‐deoxyglucose (FDG) uptake using ¹⁸F‐FDG positron emission tomography/computed tomography (PET/CT) scans and evaluated the importance of colonoscopy when incidental colorectal FDG uptake was observed. Method A prospective study was designed and conducted at a single institution over a 2‐year period. In patients undergoing PET/CT scans, all with FDG uptake in the colorectum were assigned to have colonoscopy and biopsy. The value of PET/CT scanning was studied by comparison with the colonoscopy and biopsy results. Results Among 10 978 PET/CT scans, one or more focal uptakes of FDG in the colorectum were observed in 148 (1.35%) patients. In 136 valid patients, malignant colorectal tumours and polyps were found in 23.5% and 20.5%, respectively,, while the colon in the other 56% was normal. A higher false‐positive rate was found in the right colon compared with the distal colorectum (66.2%vs 36.7%, P = 0.004). A significant increase of the maximum standardized uptake (SUVmax) value was found among normal, polyps and cancer groups. Multivariate analysis revealed that SUVmax was the risk factor for predicting colorectal cancer or polyps and FDG uptake in the right colon was a negative predictive factor for finding cancers or polyps. Conclusions Our study proves the necessity of colonoscopy when incidental FDG uptake is found on PET/CT imaging. The false‐positive FDG uptake is more commonly observed in the right colon. Although the SUVmax value is higher in cancer patients, a high SUVmax value does not necessarily result in malignancies.     

Determinants of diagnostic performance of [F-18]fluorodeoxyglucose positron emission tomography for axillary staging in breast cancer

OBJECTIVE: To prospectively investigate determinants of the accuracy of staging axillary lymph nodes in breast cancer using [F-18]fluorodeoxyglucose positron emission tomography (FDG PET). METHODS: Patients with primary operable breast cancer underwent FDG PET of the chest followed by sentinel node biopsy (SNB, n = 47) and/or complete axillary lymph node dissection (ALND, n = 23). PET scans were independently interpreted by three observers in a blinded fashion with respect to the FDG avidity of the primary tumor and the axillary status. The results were compared to histopathological analyses of the axillary lymph nodes. Clinicians were blinded to the PET results. RESULTS: Axillary lymph node specimens and FDG PET scans were evaluated in 70 patients (59% cT1). Overall, 32 (46%) had lymph node metastases as established by SNB (18/47) or ALND (14/23), 20 of which were confined to a single node. The overall sensitivity of FDG PET was 25%, with a specificity of 97%. PET results were false-negative in all 18 positive SNBs and true-positive in 8/14 in the ALND group. The performance of FDG PET depended on the axillary tumor load and the FDG avidity of the primary tumor. Intense uptake in the primary tumor was found in only 57% of the patients, and this was independent of the size. There was excellent interobserver agreement of visual assessment of FDG uptake in primary tumor and axillary lymph nodes. CONCLUSIONS: The sensitivity of FDG PET to detect occult axillary metastases in operable breast cancer was low, and it was a function of axillary tumor load and FDG avidity of the primary tumor. Even though the clinical relevance of occult disease detected by SNB needs to be confirmed, it is suggested that FDG PET in these patients should be focused on exploiting its nearly perfect specificity and the potential prognostic relevance of variable FDG uptake.     

The Impact of <Superscript>18</Superscript>F-Fluorodeoxyglucose Positron Emission Tomography Positive Lymph Nodes on Postoperative Recurrence and Survival in Resectable Thoracic Esophageal Squamous Cell Carcinoma

Background  

Induction therapy is not always beneficial for all patients. Therefore, it is important to identify the patients with a high rate of recurrence. The occurrence of lymph node metastases (LNMs) strongly influences the postoperative survival in patients with esophageal cancer. We investigated the usefulness of an LN evaluation by initial ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in prediction of postoperative recurrence for patients with resectable esophageal squamous cell carcinoma (ESCC).     

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     

Evaluation of fluorodeoxyglucose positron‐emission tomography with computed tomography for staging of urothelial carcinoma

Study Type – Diagnostic (case series)
Level of Evidence 4

OBJECTIVE

To investigate the role of ¹⁸F‐fluorodeoxyglusose positron‐emission tomography (FDG‐PET), combined with computed tomography (CT) and forced diuresis, in the staging and follow‐up of urothelial carcinoma (UC).

PATIENTS AND METHODS

We recruited 44 patients with muscle‐invasive urothelial bladder cancer (UBC) before radical cystectomy (RC), 19 under follow‐up after RC and seven after systemic chemotherapy. For those who had RC, histopathology was used as the reference standard to compare the sensitivity and specificity of FDG‐PET/CT and standard CT in detecting UBC and pelvic lymph node metastasis. Furthermore, 36 patients with ≥6 months of follow‐up imaging were considered to describe the progression of UC and extrapelvic positive FDG‐PET/CT images.

RESULTS

For the detection of primary UBC, FDG‐PET/CT was slightly more sensitive than CT (85% vs 77%) but less specific (25% vs 50%). For the detection of pelvic node metastasis FDG‐PET/CT was more sensitive than CT (57% vs 33%) with a specificity of 100% for both imaging techniques. In 20 patients, extrapelvic FDG‐PET/CT images showed suspected disease at the first evaluation. UC progressed in nine of the 10 patients who had synchronous multiple PET‐positive retroperitoneal or mediastinal lymph nodes, and in only two of the nine with unique hyperactive lesions in the lung. FDG‐PET/CT also detected a pT1G3 UC of the renal pelvis and all bone metastases detected by bone scintigraphy.

CONCLUSIONS

FDG‐PET/CT could replace standard CT and bone scintigraphy in the presurgical staging and monitoring of patients with UC after surgery or chemotherapy.     

Positron emission tomography (PET) in the urooncological evaluation of the small pelvis

Positron emission tomography (PET) with the use of (¹⁸F)2-fluoro-d-2-desoxyglucose (FDG) has been investigated to be a highly sensitive and specific imaging modality in the diagnostic of primary and recurrent tumors and in the control of therapies in numerous non-urologic cancers. The aim of this review is to validate the significance of PET as a diagnostic tool in malignant urological tumors of the small pelvis. A systematic review of the current literature concerning the role of PET for malignant prostate, testicular and bladder tumors was carried out. The data indicate no additional role for PET in comparison with conventional imaging in tumor detection and local staging for prostate, bladder or testicular cancer. Tumor recurrence in prostate cancer seems to be more effectively identified with acetate and choline than with FDG, but this effect is more pronounced with higher PSA values. The value of PET in the identification of metastatic disease in either tumor entity can not be finally outlined as the clinical data are partly missing, controversial or in the process of evaluation. FDG-PET can be regarded as accepted imaging modality in the restaging of seminomatous germ cell tumors after chemotherapy.     

Evaluation of lymph node metastases in squamous cell carcinoma of the esophagus with positron emission tomography

BACKGROUND: Previous studies suggest positron emission tomography (PET) may improve staging accuracy of esophageal cancer compared with conventional methods, especially in detecting occult distant metastases. We evaluated the accuracy of PET in the detection of lymph node metastasis prospectively with pathologic findings. METHODS: Fifty-three patients with squamous cell carcinoma underwent whole-body PET scan and chest computed tomography (CT). The findings of PET and chest CT of 50 patients who underwent curative esophagectomy with radical lymph node dissection were compared with the pathologic findings. RESULTS: Among 53 primary esophageal tumors, PET detected 51 (96.2%) and CT detected 49 (92.5%) tumors correctly. Nodal metastases were present in 108 of 436 dissected lymph node groups. PET detected 56 metastatic node groups (51.9% sensitivity, 94.2% specificity, 83.7% accuracy), compared with CT, which detected 16 (14.8% sensitivity, 96.7% specificity, 76.6% accuracy; sensitivity: p < 0.005). CONCLUSIONS: PET was more sensitive than CT in the detection of nodal metastases and may improve staging of squamous cell carcinoma of the esophagus.     

18F-2-Fluoro-2-Deoxy-D-Glucose Positron Emission Tomography Scanning Affects Surgical Management in Selected Patients With High-Risk, Operable Breast Carcinoma

Background The role of positron emission tomography (PET) scanning in determining the extent of disease in patients with breast cancer has not been defined. We investigated the utility of ¹⁸F-2-fluoro-2-deoxy-D-glucose (FDG)-PET scanning compared with conventional imaging with computed tomographic scanning and bone scanning in determining the extent of disease in patients with high-risk, operable breast cancer. Methods This was a prospective study of patients who presented to Memorial Sloan-Kettering Cancer Center for operative treatment of breast cancer. Eighty eligible patients were enrolled and underwent computed tomographic chest, abdomen, pelvis, and bone scans, followed by FDG-PET. Changes in treatment based on scan findings were recorded by the operating surgeons. Imaging findings were verified by biopsy or long-term follow-up. Results Eight (10%) of 80 patients were found to have metastatic disease that was seen on both conventional imaging and PET. Four additional patients (5%) had additional foci of disease on PET that affected treatment decisions. No patient had findings on conventional imaging alone. Conventional imaging studies resulted in a higher number of findings that generated additional tests and biopsies that ultimately had negative results (17% vs. 5% for PET). There was a statistically significant difference in specificity for PET compared with conventional imaging (P = .01). Conclusions Conventional imaging and PET were equally sensitive in detecting metastatic disease in patients with high-risk, operable breast cancer, but PET generated fewer false-positive results. FDG-PET scanning should be further studied in this setting and considered in the preoperative evaluation of selected patients with breast cancer.     

Clinical Significance of 18F-fluorodeoxyglucose Positron Emission Tomography in Superficial Esophageal Squamous Cell Carcinoma

Purpose

To assess the clinical usefulness and significance of ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) in superficial esophageal squamous cell carcinoma (ESCC).

Methods

We examined FDG-PET for 80 consecutive patients with superficial ESCC without neoadjuvant treatment. Fifty-seven patients underwent radical esophagectomy, and 23 patients received endoscopic resection. The FDG uptake index was evaluated with clinicopathological findings, and glucose transporter 1 (Glut-1) expression in primary tumors was examined immunohistochemically.

Results

The FDG uptake in primary tumors correlated with histology, depth of tumor invasion, lymph node metastasis, lymphatic invasion, vascular invasion, and Glut-1 expression. All patients with more than 4.4 maximum standardized uptake value (SUV_max) had deeper invasion of submucosa. Among 16 patients with lymph node metastasis, only two were found to have lymph node metastasis. FDG uptake, depth of tumor invasion, lymph node metastasis, and histology were found to be prognostic factors, and histology was an independent prognostic factor. In FDG uptake–positive patients, depth of tumor invasion and histology were prognostic factors.

Conclusions

FDG-PET is useful for diagnosing tumors with deeper invasion of submucosa and is helpful in making decisions regarding endoscopic treatment for superficial ESCC. Patients with FDG uptake–positive disease, deeper invasion of submucosa, poorly differentiated tumor, and poor prognosis should receive multimodal treatment.     

Preoperative intrathoracic lymph node staging in patients with non-small-cell lung cancer: accuracy of integrated positron emission tomography and computed tomography

Objective: To evaluate the accuracy of integrated positron emission tomography with ¹⁸F-fluoro-2-deoxy-d-glucose (FDG) and computed tomography (PET/CT) in preoperative intrathoracic lymph node staging in patients with non-small-cell lung cancer (NSCLC) and to ascertain the role of invasive staging in verifying positron emission tomography (PET)/computed tomography (CT) results. Methods: Retrospective, single institution study of consecutive patients with suspected or pathologically proven, potentially resectable NSCLC undergoing integrated PET/CT scanning in the same PET centre. Lymph node staging was pathologically confirmed on tissue specimens obtained at mediastinoscopy and/or thoracotomy. Statistical evaluation of PET/CT results was performed on a per-patient and per-nodal-station bases. Results: A total of 1001 nodal stations (723 mediastinal, 148 hilar and 130 intrapulmonary) were evaluated in 159 patients. Nodes were positive for malignancy in 48 (30.2%) out of 159 patients (N1 = 17; N2 = 30; N3 = 1) and 71 (7.1%) out of 1001 nodal stations (N1 = 24; N2 = 46; N3 = 1). At univariate analysis, lymph node involvement was significantly associated (p < 0.05) with the following primary tumour characteristics: increasing diameter, maximum standardised uptake value >9, central location and presence of vascular invasion. PET/CT staged the disease correctly in 128 out of 159 patients (80.5%), overstaging occurred in nine patients (5.7%) and understaging in 22 patients (13.8%). The overall sensitivity, specificity, positive and negative predictive values, and accuracy of PET/CT for detecting metastatic lymph nodes were 54.2%, 91.9%, 74.3%, 82.3% and 80.5% on a per-patient basis, and 57.7%, 98.5%, 74.5%, 96.8% and 95.6% on per-nodal-station basis. With regard to N2/N3 disease, PET/CT accuracy was 84.9% and 95.3% on a per-patient basis and on per-nodal-station basis, respectively. Referring to nodal size, PET/CT sensitivity to detect malignant involvement was 32.4% (12/37) in nodes <10 mm, and 85.3% (29/34) in nodes ≥10 mm. Conclusion: Our data show that integrated PET/CT provides high specificity but low sensitivity and accuracy in intrathoracic nodal staging of NSCLC patients and underscore the continued need for surgical staging.     

Metachronous mediastinal lymph node metastasis from ascending colon cancer: A case report and literature review

IntroductionMetachronous mediastinal lymph node metastasis without pulmonary metastasis is extremely rare in colorectal cancer, which makes the clinical diagnosis difficult and treatment strategy unclear.Prsentation of caseA case was a 59-year-old man, who had undergone right hemicolectomy for ascending colon cancer 2 years and 8 months previously, presented with enlarged mediastinal lymph nodes. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography revealed FDG was accumulated only into the mediastinal lymph nodes. Serum carcinoembryonic antigen (CEA) level was within the normal range. Six months later, the size and FDG uptake of the mediastinal lymph nodes had increased. We assumed a possibility that the mediastinal lymph nodes were metastasized from ascending colon cancer and so performed thoracoscopic-assisted resection of the mediastinal lymph nodes. Histopathological analysis revealed the resected lymph nodes were filled with moderately differentiated adenocarcinoma and a diagnosis of mediastinal lymph nodes metastasis from previously-resected ascending colon cancer was made. The patient was postoperatively followed for more than 1 year and 8 months without any sign of recurrence.DiscussionOnly 7 cases of metachronous mediastinal lymph node metastasis from colorectal cancer, including our case, have been reported in the English literature. It is difficult to clinically diagnose mediastinal lymph node metastasis.ConclusionWe report a rare case of metachronous mediastinal lymph node metastasis from ascending colon cancer with literature review. If the mediastinal lymph nodes are enlarged after colorectal cancer resection, we need to make a treatment strategy as well as a diagnostic approach considering the possibility of mediastinal lymph node metastasis.     

Fluorodeoxyglucose Positron Emission Tomography in Cutaneous Squamous Cell Carcinoma: Retrospective Analysis of 12 Patients

BACKGROUND: Whole-body 18F-fluorodeoxyglucose positron emission tomography (FDG PET) has been used for whole-body imaging modality in detecting malignancy in clinical oncology. However, only a few reports of FDG PET in skin cancers have been described, except for melanoma and lymphoma. OBJECTIVE: To report on the usefulness of FDG PET as a baseline workup study for patients with cutaneous squamous cell carcinoma (SCC). METHODS: There were 12 cases of SCC (9 cases with high-risk SCC). Of the 12, FDG PET was performed for staging in 11 patients and for restaging in 1 patient 1 year after wide excision. RESULTS: Primary lesions were detected in nine cases (83.3%), lymph node involvement in three cases (25.0%), and distant. organ (lung) involvement in one case (8.3%). In one patient whose primary lesion was positive, stomach cancer with involvement of adrenal glands, omentum, and lymph nodes was incidentally detected. All of the patients with high-risk SCC showed FDG uptakes of the primary lesions, and the patients with FDG uptakes in lymph nodes and distant organ had high-risk SCC. CONCLUSION: There have been no comparative studies on the cost-effectiveness between sentinel lymph node biopsy and FDG PET in SCC patients. However, considering the noninvasiveness and thoroughness in checking the whole body, including distant organs, FDG PET may have clinical value as a baseline workup study for patients with high-risk SCC.     

Uptake of 2-deoxy, 2-(18F) fluoro-D-glucose in bladder cancer: animal localization and initial patient positron emission tomography

An orthotopically transplanted, locally metastasizing rat bladder tumor model was developed to evaluate the extent of uptake of fluoro-deoxy-glucose (FDG) in bladder cancer. Significant uptake of FDG in localized bladder tumors in rats was shown, with an average tumor-to-blood ratio of 39 at 2 hours after intravenous FDG administration. Metastases (3 nodal and 1 peritoneal) also showed significant uptake of FDG, with an average metastasis-to-blood ratio of 21.7, and tumor involved-to-normal lymph node ratio of 5.3. Because FDG is excreted in the urine, urinary FDG potentially could prevent the use of FDG/positron emission tomography (FDG/PET) scanning for localized bladder cancer. Bladder lavage successfully reduced the retention of FDG in the normal rat bladder, with an estimated uptake ratio of tumor-to-normal bladder of 13.1 after 5 ml. saline irrigation. Based on these data, we performed an FDG/PET scan of a patient with biopsy proved recurrent intravesical bladder cancer after radiation therapy. Computerized tomography (CT) of the pelvis showed abnormalities consistent with radiation scarring and extravesical tumor. Due to the scarring, the extent of tumor growth could not be determined. The patient also had pulmonary opacities seen on chest radiography. The FDG/PET scan of this patient showed significant extravesical uptake in the pelvis, confirming the abnormality noted on CT. Good images of the clinically apparent metastases in the chest also were obtained. These preliminary data indicate that FDG/PET imaging of bladder cancer is feasible and it may provide new information for the diagnosis and staging of patients with bladder cancer.     

FDG-PET/CT for the Preoperative Lymph Node Staging of Invasive Bladder Cancer

Background

Locoregional lymph node metastasis is an important prognostic factor in patients with bladder cancer. Multimodal treatment, depending on preoperative stage, may improve survival. The standard imaging modalities for staging (computed tomography [CT] or magnetic resonance imaging [MRI]) have an accuracy range of 70–90% for lymph node staging. A more accurate preoperative diagnostic test could improve survival rates even more.

Objective

To determine whether the use of 2-deoxy-2 [F] fluoro-D-glucose (FDG) positron emission tomography (PET) in combination with CT (FDG-PET/CT) can increase the reliability of preoperative lymph node staging in patients with nonmetastatic invasive bladder cancer (T2 or higher, M0) or recurrent high-risk superficial disease (T1G3 with or without Tis, M0).

Design, setting, and participants

Fifty-one patients underwent a preoperative FDG-PET/CT between April 2004 and December 2007. Independent of the result for lymph node status, all patients underwent a radical cystectomy and an extended lymphadenectomy. The FDG-PET/CT and CT results were compared with the definitive pathologic results.

Measurements

Among the 51 patients, 13 patients had metastatically involved locoregional lymph nodes, diagnosed on histopathology. In six patients, these nodes demonstrated increased FDG uptake on PET. In seven patients, PET/CT did not diagnose the positive lymph nodes. PET/CT was false positive in one patient.

Results and limitations

For the diagnosis of node-positive disease, the accuracy, the sensitivity, and the specificity of FDG-PET/CT were 84%, 46%, and 97%, respectively. When analysing the results of CT alone, there was accuracy of 80%, sensitivity of 46%, and specificity of 92%. The use of FDG-PET/CT is hampered by technical limitations.

Conclusions

We found no advantage for combined FDG-PET/CT over CT alone for lymph node staging of invasive bladder cancer or recurrent high-risk superficial disease.