Positron emission tomography in non-medullary thyroid cancer

While iodine scanning is the mainstay of functional imaging in differentiated thyroid cancer, there is now a significant body of literature regarding positron emission tomography with 2-fluoro-2-deoxy glucose in thyroid cancer. This clinical review will examine the evidence supporting the use of 2-fluoro-2-deoxy glucose-positron emission tomography throughout the diagnosis and management of thyroid cancer, and provide suggestions for its clinical use and potential future roles.     

Colorectal tubulovillous adenomas identified on fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography scans

Objective The aim of this retrospective study was to assess the significance of incidental focal colonic lesions on fluoro‐2‐deoxy‐d ‐glucose positron emission tomography/computed tomography (FDG PET/CT) scans in patients undergoing staging for noncolorectal cancer. Method Of the 110 patients in our PET/CT database, 10 were found to have abnormally high uptake of tracer in their large bowel. Results Seven patients who underwent further endoscopic evaluation of these abnormalities had intermediate to high‐risk adenomatous polyps. Conclusion Benign colonic polyps produce high‐intensity focal FDG uptake in large bowel. Endoscopic evaluation is recommended before curative resectional surgery of the presenting cancer where appropriate.     

Positron emission tomography (PET) positive thyroid incidentaloma: the risk of malignancy observed in a tertiary referral center

An incidental finding of focal thyroid uptake (thyroid incidentaloma) from an 18F-fluorodeoxyglucose positron emission tomography (PET) positron presents a diagnostic challenge. We evaluated the incidence of thyroid incidentaloma identified by PET scans and the likelihood of malignancy associated with this finding. Records from all patients from January 1, 2000 to November 30, 2003 who had focal thyroid uptake without any history of thyroid disease were culled. Of the 6241 PET scans performed, focal thyroid uptake was observed in 76 patients (1.2%). Only 14 patients (18%) underwent biopsy. Four of 14 patients (28.6%) had papillary thyroid carcinoma, 7 (50%) had hyperplasia, and 1 each had thyroiditis, nodular goiter, and follicular neoplasm. The incidence of PET thyroid incidentalomas was 1.2 per cent and the incidence of malignancy was 28.6 per cent. Given the high likelihood of malignancy, a further diagnostic workup for surgically fit patients is warranted.     

Positron emission tomography

Summary One of the most exciting new techniques introduced in the last ten years is positron emission tomography (PET). PET provides quantitative, three-dimensional images for the study of specific biochemical and physiological processes in the human body. This approach is analogous to quantitativein vivo autoradiography but has the added advantage of permitting non-invasivein vivo studies. PET scanning requires a small cyclotron to produce short-lived positron emitting isotopes such as oxygen-15, carbon-11, nitrogen-13 and fluorine-18.Proper radiochemical facilities and advanced computer equipment are also needed. Most important, PET requires a multidisciplinary scientific team of physicists, radiochemists, mathematicians, biochemists and physicians. This review analyses the most recent trends in imaging technology, radiochemistry, methodology, and clinical applications of positron emission tomography.Reproduced with kind permission of Pergamon Press from the special issue of Radiation Physics and Chemistry on Radiation and Medicine (1984). Guest Editors: B. C. Lentle and H. Singh.     

Positron emission tomography in a patient with renal malacoplakia

Positron emission tomography is increasingly used for the diagnosis of occult infection or malignancy. The altered metabolic rate of cells in areas of malignancy or infection provides a sensitive method to identify pathology that is otherwise not identified by standard imaging methods. This case report describes a patient who presented with a pyrexia of unknown origin and renal impairment. She had a positron emission tomography scan that showed intense accumulation of fluoro-deoxy-glucose in both kidneys. Subsequent renal biopsy results showed a diagnosis of malacoplakia, the treatment of which resulted in a resolution of the fever and a stabilization of renal function. This is the first report of the positron emission tomographic appearance of renal malacoplakia.     

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 (PET) assessment of renal perfusion

Positron emission tomography (PET) is a radionuclide imaging technique that allows noninvasive mapping of radiopharmaceutical concentrations in three-dimensional space. PET methods have been described for imaging and quantification of renal perfusion using cyclotron-produced (15)O-water and (13)N-ammonia, as well as using generator-produced (82)RbCl and (62)Cu-ETS. Although the majority of clinical PET facilities will lack the in-house biomedical cyclotron needed for (15)O and (13)N production, the generator-produced tracers are available to virtually any clinical site with a PET camera. Studies with these radiopharmaceuticals have largely focused on methodologic issues, and agent validation for renal blood flow measurements. However, the resulting PET methods for quantification of renal perfusion do appear suitable for application to both research and clinical problems in renal pathophysiology.     

Usefulness of dynamic fluorodeoxyglucose positron emission tomography/computed tomography in diagnosing pulmonary arteriovenous malformation mimicking a lung tumour

A 61-year-old male patient with known kidney dysfunction who underwent a non-contrast thorax CT and was then referred to our department for metabolic assessment of solitary pulmonary nodule (SPN). The patient underwent dynamic FDG PET/CT to differentiate benign from malignant SPN. This case illustrates the usefulness of dynamic FDG PET/CT imaging when assessing SPN especially in patients with suspicion for pulmonary arterio-venous malformation accompanying renal failure or contrast allergy.     

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.     

The influence of 18F-fluorodeoxyglucose positron emission tomography/computed tomography on the N- and M-staging and subsequent clinical management of intrahepatic cholangiocarcinoma

BackgroundIntrahepatic cholangiocarcinoma (ICC) is a highly metastatic cancer. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) enables sensitive tumor and metastasis detection. Our aim is to evaluate the influence of pre-treatment PET/CT on the N- and M-staging and subsequent clinical management in ICC patients.MethodsBetween August 2010 and August 2018, 660 consecutive ICC patients, without prior anti-tumor treatments nor other malignancies, were enrolled. The diagnostic performance of PET/CT on the N- and M-staging was compared with conventional imaging, and the preoperative staging accuracy and treatment re-allocation by PET/CT were retrospectively calculated. Survival difference was compared between patients receiving PET/CT or not after propensity score matching.ResultsPatients were divided into group A (n=291) and group B (n=369) according to whether PET/CT was performed. Among 291 patients with both PET/CT and conventional imaging for staging in group A, PET/CT showed significantly higher sensitivity (83.0% vs. 70.5%, P=0.001), specificity (88.3% vs. 74.9%, P<0.001) and accuracy (86.3% vs. 73.2%, P<0.001) than conventional imaging in diagnosing regional lymph node metastasis, as well as higher sensitivity (87.8% vs. 67.6%, P<0.001) and accuracy (93.5% vs. 89.3%, P=0.023) in diagnosing distant metastasis. Overall, PET/CT improved the accuracy of preoperative staging from 60.1% to 71.8% (P<0.001), and modified clinical treatment strategy in 5.8% (17/291) of ICC patients, with unique roles in different tumor-node-metastasis (TNM) stages. High tumor-to-non-tumor ratio (TNR) predicted poor overall survival [hazard ratio (HR) = 2.17; 95% confidence interval (CI): 1.49–3.15; P<0.001]. Furthermore, patients performing PET/CT had longer overall survival compared with those without PET/CT (HR =0.74; 95% CI: 0.58–0.93; P=0.011) after propensity score matching.ConclusionsPET/CT was valuable for diagnosing regional lymph node metastasis and distant metastasis in ICC patients, and facilitated accurate tumor staging and optimal treatment allocation.     

Positron emission tomography with F-18-deoxyglucose in patients with differentiated thyroid carcinoma, elevated thyroglobulin levels, and negative iodine scans

Introduction: In patients with differentiated thyroid carcinoma, elevated serum levels of thyroglobulin (hTg) may occur in spite of otherwise negative diagnostic procedures and in particular in spite of a negative iodine-131 scan. Positron emission tomography with F-18-deoxyglucose (FDG-PET) is a potentially useful method for the detection of metastatic lesions or the recurrence of thyroid cancer. We aimed to investigate whether FDG-PET is capable of detecting metastastic lesions or recurrence in patients with differentiated thyroid carcinoma, elevated serum levels of thyroglobulin, and otherwise negative diagnostic procedures, including the iodine-131 scan. Methods: From a group of 500 patients with differentiated thyroid carcinoma, a subgroup of 32 patients had elevated serum hTg-levels, negative iodine-131 scans, negative cervical and abdominal ultrasound, and negative X-ray of the chest. In 12 of these patients (hTg 77.8±94.3 ng/ml, range 1.5 – 277 ng/ml, median 20 ng/ml), FDG-PET was performed. All but one FDG-PET study was performed in a state of hypothyroidism (TSH 75.8±32.2 μIU/ml, range 31 – 116 μIU/ml, median 74.6 μIU/ml). Results: In 6 of the 12 patients investigated, the FDG-PET was positive. In three of the patients, the diagnosis was confirmed by computed tomography or magnetic resonance imaging. In patients with a positive FDG-PET finding, the hTg level was 146.7±90.1 ng/ml (23 – 277 ng/ml, median 144.5 ng/ml). In contrast, in patients with a negative finding the hTg level was only 9.0±7.6 ng/ml (range 1.5 – 17 ng/ml, median 8.1 ng/ml), P = 0.01. Conclusion: These preliminary results show that in patients with differentiated thyroid carcinoma, elevated hTg levels, and otherwise negative “conventional” diagnostic procedures, FDG-PET is helpful in detecting metastatic lesions. Received: 15 November 1997     

Positron emission tomography with 68-Ga-EDTA and computed tomography in patients with subarachnoid haemorrhage

Summary 26 patients with subarachnoid haemorrhage (SAH) were investigated with 68-Ga-EDTA and positron emission tomography (PET) in order to evaluate the presence of a blood brain barrier (BBB) disturbance. Only one patient showed a BBB disruption. It is suggested that increased levels of substances with higher molecular weight than 68-Ga-EDTA in the cerebrospinal fluid (CSF) are the result of a change in the metabolism of the CSF and the brain tissue caused by a SAH.     

Incidental focal colonic lesions found on 18Fluorodeoxyglucose positron emission tomography/computed tomography scan: further support for a national guideline on definitive management

Aim ¹⁸Fluorodeoxyglucose (¹⁸FDG) positron emission tomography/computed tomography (PET/CT) is an established part of staging in a wide variety of malignancies. Incidental abnormal uptake of ¹⁸FDG of unknown significance is frequently encountered. Therefore, we investigated patients with abnormal colonic uptake of ¹⁸FDG, determined by PET/CT images, using colonoscopy. Method The radiology reports of all patients referred to a tertiary referral centre for a PET/CT scan were reviewed retrospectively. Patients with abnormal colonic uptake of ¹⁸FDG were identified and the PET/CT findings were correlated with colonoscopic findings. Results Of 555 consecutive patients identified over a 26‐month period, 53 had abnormal colonic uptake of ¹⁸FDG, as determined by PET/CT images. Twenty‐nine were not investigated following discussion in a specialist multidisciplinary (MDT) meeting, according to local protocol. Twenty out of 24 patients investigated by endoscopy had a colonic lesion correlating to the site identified on the PET/CT image: 16 patients had tubulovillous adenomas (nine of which were > 10 mm), two had invasive adenocarcinomas, two had diverticular disease and one had collagenous colitis; no colonic lesion was detected in three. These findings were incidental and not related to the primary diagnosis for which the scan was being performed. Accordingly, a positive predictive value of 83% is associated with the finding of abnormal uptake of ¹⁸FDG on PET/CT images. Conclusion Incidental abnormal colonic uptake of ¹⁸FDG, determined by a PET/CT scan requires definitive colonic investigation in patients suitable for further treatment because significant colonic pathology is frequently identified. The benefit of this approach should be discussed in specialist MDT meetings and tailored to each patient; however, national guidelines for management are required.     

Combined 18F‐fluorocholine and 18F‐fluoride positron emission tomography/computed tomography imaging for staging of high‐risk prostate cancer

Study Type – Diagnosis (cohort) Level of Evidence 2a What's known on the subject? and What does the study add? Positron emission tomography/computed tomography (PET/CT) with choline and fluoride for the detection of metastases in patients with prostate cancer have each been evaluated, with mixed results. Choline PET/CT has been evaluated against pelvic lymphadenectomy, generally with a low sensitivity but a high specificity; however, the study populations have been heterogenous. Fluoride PET/CT has been evaluated against other imaging methods, such as bone scan, single photon emission CT and MRI, and has been shown to have high specificity as well as sensitivity for bone metastases, but there are no studies with biopsy verification. This is the first study that evaluates the clinical use of both choline and fluoride PET/CT on the same patients in a well‐defined population of patients with high‐risk prostate cancer.

OBJECTIVE

• ? To investigate how often positron emission tomography/computed tomography (PET/CT) scans, with both ¹⁸F‐fluorocholine and ¹⁸F‐fluoride as markers, add clinically relevant information for patients with prostate cancer who have high‐risk tumours and a normal or inconclusive planar bone scan.

PATIENTS AND METHODS

• ? Patients with prostate cancer with prostate specific antigen (PSA) levels between 20 and 99 ng/mL and/or Gleason score 8–10 tumours, planned for treatment with curative intent based on routine staging with a negative or inconclusive bone scan, were further investigated with a ¹⁸F‐fluorocholine and a ¹⁸F‐fluoride PET/CT.
• ? None of the patients received hormonal therapy before the staging procedures were completed.

RESULTS

• ? For 50 of the 90 included patients (56%) one or both PET/CT scans indicated metastases.
• ? ¹⁸F‐fluorocholine PET/CT indicated lymph node metastases and/or bone metastases in 35 patients (39%).
• ? ¹⁸F‐fluoride PET/CT was suggestive for bone metastases in 37 patients (41%).
• ? In 18 patients (20%) the PET/CT scans indicated widespread metastases, leading to a change in therapy intent from curative to non‐curative.
• ? Of the patients with positive scans, 74% had Gleason score 8–10 tumours. Of the patients with Gleason score 8–10 tumours, 64% had positive scans.

CONCLUSIONS

• ? PET/CT scans with ¹⁸F‐fluorocholine and ¹⁸F‐fluoride commonly detect metastases in patients with high‐risk prostate cancer and a negative or inconclusive bone scan.
• ? For 20% of the patients the results of the PET/CT scans changed the treatment plan.

     

Pelvic/retroperitoneal salvage lymph node dissection for patients treated with radical prostatectomy with biochemical recurrence and nodal recurrence detected by [11C]choline positron emission tomography/computed tomography

Background

The management of patients with clinical recurrence of prostate cancer after radical prostatectomy (RP) remains challenging.

Objective

To determine whether the removal of positive lymph nodes at [11C]choline positron emission tomography/computed tomography (PET/CT) scan may have an impact on the prognosis of patients with biochemical recurrence (BCR) and nodal recurrence after RP.

Design, setting, and participants

Prospective analysis of 72 patients affected by BCR after RP associated with a nodal pathologic [11C]choline PET/CT scan.

Intervention

Patients underwent salvage lymph node dissection (LND).

Measurements

Biochemical response (BR) to treatment was defined as prostate-specific antigen (PSA) <0.2 ng/ml at 40 d after salvage LND. Kaplan-Meier and Cox regression analyses addressed time to and predictors of clinical recurrence (CR) after salvage LND, respectively.

Results and limitations

Overall, 56.9% of patients achieved BR. Mean and median follow-up after LND were 39.4 and 39.8 mo, respectively. The 5-yr BCR-free survival rate was 19%. Preoperative PSA <4 ng/ml (hazard ratio [HR]: 0.12; p = 0.005), time to BCR <24 mo (HR: 7.52; p = 0.005), and negative lymph nodes at previous RP (HR: 0.19; p = 0.04) represented independent predictors of BR. Overall, 5-yr CR-free and cancer-specific survival were 34% and 75%, respectively. At multivariable analyses, only PSA >4 ng/ml (HR: 2.13; p = 0.03) and the presence of retroperitoneal uptake at PET/CT scan (HR = 2.92; p = 0.004) represented independent preoperative predictors of CR. Similarly, the presence of pathologic nodes in the retroperitoneum (HR: 2.78; p = 0.02), higher number of positive lymph nodes (HR: 1.04; p = 0.006), and complete BR to salvage LND (HR: 0.31; p = 0.002) represented postoperative independent predictors of CR. Main limitations consisted of the lack of a control group and the heterogeneity of patients included in the analyses.

Conclusions

Salvage LND is feasible in patients with BCR after RP and nodal pathologic uptake at [11C]choline PET/CT scan. Biochemical response after surgery can be achieved in a consistent proportion of patients. Although most patients invariably progressed to BCR after surgery at longer follow-up, 35% of patients showed the absence of CR at 5 yr.     

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.