A Review of Hypoxia Imaging Using 18F-Fluoromisonidazole Positron Emission Tomography

Tumor hypoxia is an essential factor related to malignancy, prognosis, and resistance to treatment. Positron emission tomography (PET) is a modality that visualizes the distribution of radiopharmaceuticals administered into the body. PET imaging with [18F]fluoromisonidazole ([18F]FMISO) identifies hypoxic tissues. Unlike [18F]fluorodeoxyglucose ([18F]FDG)-PET, fasting is not necessary for [18F]FMISO-PET, but the waiting time from injection to image acquisition needs to be relatively long (e.g., 2-4 h). [18F]FMISO-PET images can be displayed on an ordinary commercial viewer on a personal computer (PC). While visual assessment is fundamental, various quantitative indices such as tumor-to-muscle ratio have also been proposed. Several novel hypoxia tracers have been invented to compensate for the limitations of [18F]FMISO.

A third of the radiotracer dose: two decades of progress in pediatric [18F]fluorodeoxyglucose PET/CT and PET/MR imaging

OBJECTIVES

To assess the evolution of administered radiotracer activity for F-18-fluorodeoxyglucose (18F-FDG) PET/CT or PET/MR in pediatric patients (0-16 years) between years 2000 and 2021.

METHODS

Pediatric patients (≤ 16 years) referred for 18F-FDG PET/CT or PET/MR imaging of the body during 2000 and 2021 were retrospectively included. The amount of administered radiotracer activity in megabecquerel (MBq) was recorded, and signal-to-noise ratio (SNR) was measured in the right liver lobe with a 4 cm3 volume of interest as an indicator for objective image quality. Descriptive statistics were computed.

RESULTS

Two hundred forty-three children and adolescents underwent a total of 466 examinations. The median injected 18F-FDG activity in MBq decreased significantly from 296 MBq in 2000-2005 to 100 MBq in 2016-2021 (p < 0.001), equaling approximately one-third of the initial amount. The median SNR ratio was stable during all years with 11.7 (interquartile range [IQR] 10.7-12.9, p = 0.133).

CONCLUSIONS

Children have benefited from a massive reduction in the administered 18F-FDG dose over the past 20 years without compromising objective image quality.

CLINICAL RELEVANCE STATEMENT

Radiotracer dose was reduced considerably over the past two decades of pediatric F-18-fluorodeoxyglucose PET/CT and PET/MR imaging highlighting the success of technical innovations in pediatric PET imaging.

KEY POINTS

• The evolution of administered radiotracer activity for F-18-fluorodeoxyglucose (18F-FDG) PET/CT or PET/MR in pediatric patients (0-16 years) between 2000 and 2021 was assessed. • The injected tracer activity decreased by 66% during the study period from 296 megabecquerel (MBq) to 100 MBq (p < 0.001). • The continuous implementation of technical innovations in pediatric hybrid 18F-FDG PET has led to a steady decrease in the amount of applied radiotracer, which is particularly beneficial for children who are more sensitive to radiation.

Characterizing Rosai-Dorfman disease with [18F]FDG PET/CT: a retrospective analysis of a single-center study

OBJECTIVES

Rosai-Dorfman disease (RDD) is a rare non-Langerhans cell histiocytic proliferative disorder. We performed a retrospective study to characterize the clinical and [18F]FDG PET/CT features of RDD.

METHODS

We retrospectively recruited 38 RDD patients with [18F]FDG PET/CT scan in our center. [18F]FDG PET/CT features were assessed, and clinical and follow-up data were recorded.

RESULTS

In the recruited patients, 20/38 (52.6%) patients had single-system disease, while others (18/38, 47.4%) had disease affecting multiple system. RDD most commonly involved the upper respiratory tract (47.4%), followed by cutaneous/subcutaneous lesion (39.5%), lymph node (36.8%), bone (31.6%), central nervous system (28.9%), and cardiovascular system (13.2%) in the recruited patients. In PET/CT, the RDD lesions were FDG-avid, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels (r = 0.418, p = 0.014), and negatively correlated with hemoglobin levels (r =  -0.359, p = 0.036). The overall response rate of the first-line treatment was 80.8% in newly diagnosed RDD patients, and for patients with relapsed/progressive RDD, the overall response rate was 72.7%.

CONCLUSION

[18F]FDG PET/CT could be a useful tool for evaluating RDD.

KEY POINTS

• About half of the patients with Rosai-Dorfman disease had single-system disease, while others had disease affecting multiple system. Rosai-Dorfman disease most commonly involved the upper respiratory tract, followed by cutaneous/subcutaneous lesion, lymph node, bone, central nervous system, and cardiovascular system. • In [18F]FDG PET/CT, Rosai-Dorfman disease was usually hypermetabolic, and the SUVmax of the hottest lesion in an individual patient was positively correlated with C-reactive protein levels. • Rosai-Dorfman disease usually has a high overall response rate after treatment.

In Alzheimer's disease, amyloid beta accumulation is a protective mechanism that ultimately fails

HYPOTHESIS AND PREDICTIONS

Here, we claim that amyloid beta (Aβ) accumulation is a protective mechanism that ultimately fails. We predict that more Aβ accumulates in regions with higher rates of glucose metabolism, reaching a maximum followed by progression of pathology.

BACKGROUND

Aβ accumulation is characteristic of Alzheimer's disease (AD) but the accumulation does not correlate with cognitive decline, unlike the rates of glucose metabolism.

STRATEGY

We compared averaged and individual estimates of regional binding potentials of [11 C]Pittsburgh compound B to regionally averaged and individual values of metabolism of [18 F]fluorodeoxyglucose in brain regions of volunteers with AD.

SIGNIFICANCE

The claim explains the cognitive decline in some patients at a significantly lower level of Aβ deposition than in other patients, as well as the presence of cognitively healthy individuals with high Aβ accumulation. With further support of the hypothesis, the significance of Aβ accumulation in brains of patients with AD may require revision.

Advances in Radiopharmaceutical Sciences for Vascular Inflammation Imaging: Focus on Clinical Applications

Biomedical imaging technologies offer identification of several anatomic and molecular features of disease pathogenesis. Molecular imaging techniques to assess cellular processes in vivo have been useful in advancing our understanding of several vascular inflammatory diseases. For the non-invasive molecular imaging of vascular inflammation, nuclear medicine constitutes one of the best imaging modalities, thanks to its high sensitivity for the detection of probes in tissues. 2-[¹⁸F]fluoro-2-deoxy-d-glucose ([¹⁸F]FDG) is currently the most widely used radiopharmaceutical for molecular imaging of vascular inflammatory diseases such as atherosclerosis and large-vessel vasculitis. The combination of [¹⁸F]FDG and positron emission tomography (PET) imaging has become a powerful tool to identify and monitor non-invasively inflammatory activities over time but suffers from several limitations including a lack of specificity and avid background in different localizations. The use of novel radiotracers may help to better understand the underlying pathophysiological processes and overcome some limitations of [¹⁸F]FDG PET for the imaging of vascular inflammation. This review examines how [¹⁸F]FDG PET has given us deeper insight into the role of inflammation in different vascular pathologies progression and discusses perspectives for alternative radiopharmaceuticals that could provide a more specific and simple identification of pathologies where vascular inflammation is implicated. Use of these novel PET tracers could lead to a better understanding of underlying disease mechanisms and help inform the identification and stratification of patients for newly emerging immune-modulatory therapies. Future research is needed to realize the true clinical translational value of PET imaging in vascular inflammatory diseases.

FDG PET-CT in rheumatological diseases

2-deoxy-2[¹⁸F]fluoro-D-glucose (FDG) PET-CT has revolutionized oncological imaging. The cellular processes that make cancer cells visible on FDG PET-CT also occur in a number of inflammatory cells. Exploiting this phenomenon has led to a growth of evidence supporting the use of FDG PET-CT in a wide range of infective and inflammatory diseases. Rheumatological diseases can affect multiple sites within the musculoskeletal system alongside multi-organ extra-articular disease manifestations. Inflammation is central to these diseases, making FDG PET-CT a logical choice. In this review article we describe the various applications of FDG PET-CT in rheumatological diseases using illustrative examples to highlight the beneficial role of FDG PET-CT in each case.

Can the function of the tubarial glands be evaluated using [99mTc]pertechnetate SPECT/CT, [18F]FDG PET/CT, and [11C]methionine PET/CT?

BACKGROUND

The tubarial glands (TGs) are recently reported as newly found salivary gland structures that can be organs at risk predominantly localized in the tori tubarius in the nasopharynx using prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT). The aims of this study were to analyze uptake in the TGs compared with that in the other salivary glands and palatine tonsils using [^99mTc]pertechnetate SPECT/CT, [¹⁸F]FDG PET/CT, and [¹¹C]methionine PET/CT and to confirm whether these three imaging modalities are useful in evaluating the physiological function of the TGs. Twelve and 130 patients, who underwent [^99mTc]pertechnetate SPECT/CT and [¹⁸F]FDG/[¹¹C]methionine PET/CT, respectively, were retrospectively included. [^99mTc]pertechnetate uptake in the tori tubarius was visually assessed and semiquantitatively compared with that in the background, parotid salivary glands (PSGs), submandibular salivary glands (SmSGs), and sublingual salivary glands (SlSGs). Correlations of [¹⁸F]FDG and [¹¹C]methionine uptakes in the tori tubarius with those in the other three salivary glands and palatine tonsils were analyzed.

RESULTS

[^99mTc]pertechnetate uptake in the tori tubarius was invisible and was not significantly higher than that in the background. Both [¹⁸F]FDG and [¹¹C]methionine uptakes in the tori tubarius were correlated with that in the palatine tonsils (r = 0.56, p < 0.0001; r = 0.48, p < 0.0001, respectively). [¹⁸F]FDG uptake in the tori tubarius was not positively correlated with that in the PSGs, SmSGs, and SlSGs (r = - 0.19, p = 0.03; r = - 0.02, p = 0.81; r = 0.12, p = 0.17, respectively). [¹¹C]methionine uptake in the tori tubarius was correlated with that in the SmSGs and SlSGs (r = 0.24, p = 0.01; r = 0.32, p < 0.01, respectively), but not with that in the PSGs (r = 0.16, p = 0.08).

CONCLUSIONS

The TGs were undetectable on [^99mTc]pertechnetate SPECT/CT. Both [¹⁸F]FDG and [¹¹C]methionine uptakes in the tori tubarius were clearly affected by that in the palatine tonsils and was little related to that in the other salivary glands. Therefore, it seems difficult to evaluate the physiological function of the TGs as salivary glands using [^99mTc]pertechnetate SPECT/CT, [¹⁸F]FDG PET/CT, and [¹¹C]methionine PET/CT imaging.

Discontinuation of metformin to prevent metformin-induced high colonic FDG uptake: is 48 h sufficient?

Objective

In this retrospective, single-center observational study, we investigated whether discontinuing metformin for at least 48 h prevents metformin-induced [¹⁸F]fluorodeoxyglucose (FDG) uptake in all segments of the colon.

Methods

Patients with type 2 diabetes who were using metformin before undergoing an FDG PET/CT scan were included. Two groups were created: patients who discontinued metformin for less than 48 h (< 48 h group) and patients who discontinued metformin for between 48 and 72 h (≥ 48 h group). A control group comprised non-diabetic patients who were not using metformin before undergoing an FDG PET/CT. We visually scored the uptake of FDG in four segments of the colon—the ascendens, transversum, descendens, and rectosigmoid—using a four-point scale (1–4) and considered scores of 3 or 4 to be clinically significant.

Results

Colonic FDG uptake in the ≥ 48 h group (n = 23) was higher than uptake in the control group (n = 96) in the colon descendens [odds ratio (OR) 14.0; 95% confidence interval (CI) 4.8–40.9; p value: 0.001] and rectosigmoid (OR 11.3; 95% CI 4.0–31.9; p value: 0.001), and there was no difference in the colon ascendens and transversum. Colonic FDG uptake in the < 48 h group (n = 25) was higher than uptake in the ≥ 48 h group (n = 23) in the colon transversum (OR 4.8; 95% CI 1.3–18.5; p value: 0.022) and rectosigmoid (p value: 0.023), and there was no difference in the colon ascendens and descendens.

Conclusions

Discontinuing metformin for 48 h before undergoing an FDG PET/CT still gives a high uptake in the distal parts of the colon when compared with non-diabetic patients who are not using metformin. Discontinuing metformin for 48 h seems to be useful for scanning the more proximal segments of the colon.

Double-strand breaks in lymphocyte DNA of humans exposed to [18F]fluorodeoxyglucose and the static magnetic field in PET/MRI

BACKGROUND

Given the increasing clinical use of PET/MRI, potential risks to patients from simultaneous exposure to ionising radiation and (electro)magnetic fields should be thoroughly investigated as a precaution. With this aim, the genotoxic potential of 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) and a strong static magnetic field (SMF) were evaluated both in isolation and in combination using the γH2AX assay detecting double-strand breaks in lymphocyte DNA.

METHODS

Thirty-two healthy young volunteers allocated to three study arms were exposed to [18F]FDG alone, to a 3-T SMF alone or to both combined over 60 min at a PET/CT or a PET/MRI system. Blood samples taken after in vivo exposure were incubated up to 60 min to extend the irradiation of blood by residual [18F]FDG within the samples and the time to monitor the γH2AX response. Absorbed doses to lymphocytes delivered in vivo and in vitro were estimated individually for each volunteer exposed to [18F]FDG. γH2AX foci were scored automatically by immunofluorescence microscopy.

RESULTS

Absorbed doses to lymphocytes exposed over 60 to 120 min to [18F]FDG varied between 1.5 and 3.3 mGy. In this time interval, the radiotracer caused a significant median relative increase of 28% in the rate of lymphocytes with at least one γH2AX focus relative to the background rate (p = 0.01), but not the SMF alone (p = 0.47). Simultaneous application of both agents did not result in a significant synergistic or antagonistic outcome (p = 0.91).

CONCLUSION

There is no evidence of a synergism between [18F]FDG and the SMF that may be of relevance for risk assessment of PET/MRI.

Quantitative 18F-FDG PET analysis in survival rate prediction of patients with non-small cell lung cancer

The aim of the present study was to investigate the prognostic value of quantitative [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) parameters for patients with non-small cell lung cancer (NSCLC). The present study conducted a retrospective review of the medical records of 203 patients with NSCLC, of which 193 patients underwent baseline 18F-FDG PET/CT prior to initial therapy. Multivariate analyses using Cox's proportional hazards regression were performed for the assessment of the association between initial PET/CT measurements and overall survival (OS). The multivariate models were adjusted for sex, age, smoking status, disease stage, standardized uptake value (SUV), standardized uptake value corrected for lean body mass (SUL), metabolic tumor volume (MTV), total lesion glycolysis (TLG) and standard deviation of SUV (SD). Kaplan-Meier (K-M) estimator curves were constructed following the formation of three approximately equal-sized groups using tertiles for each PET/CT measurement (n=65, 64 and 64). OS curves were plotted using K-M estimator curves. Results demonstrated significant associations between OS and MTVPET volume computerized assisted reporting (PETVCAR), MTV2.5, MTV25%, MTV42% and TLGPETVCAR; however, no significant associations were identified between OS and MTV50%, MTV75%, TLG2.5, all SUV and SUL. Subgroup analyses according to pathology demonstrated that there were statistically significant associations between OS and stage (P<0.001), MTV50% (P=0.002) and MTV42% (P=0.004) in the adenocarcinoma group, and SULmean (P=0.010), MTV25% (P=0.005) and MTV42% (P=0.001) in the squamous cell carcinoma group; however, no significant differences were identified between any other group. Furthermore, there was a significant association between OS and MTV42% (P=0.02) and MTV50% (P=0.04) in the early-stage group; however, no significant differences were identified in the advanced-stage group. K-M estimator curve analyses demonstrated that the pathology (P=0.01), stage (P<0.001) and all PET metabolic parameters with the exception of SD were significantly associated with OS (P<0.05). No significant associations were demonstrated between SD and OS. In conclusion, 18F-FDG PET/CT MTVPETVCAR, MTV2.5, MTV25%, MTV42% and TLGPETVCAR exhibit prognostic values with regard to OS. Overall, selection of appropriate metabolic parameters may predict NSCLC prognosis.

Frontal hypometabolism in elderly breast cancer survivors determined by [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET): a pilot study

PURPOSE

The term "chemobrain" is sometimes used to denote deficits in neuropsychological functioning that may occur as a result of cancer treatment. As breast cancer survivors now commonly reach late life, it is not known whether previous exposure to chemotherapy may affect long-term risk for cognitive impairment. To help address this concern, this study tested whether successfully surviving chemotherapy earlier in life was associated with later differences in brain metabolic function as an older adult compared to controls. This question was examined using positron emission tomography measures of brain glucose metabolism in elderly women cancer survivors.

METHODS

Breast cancer survivors (N = 10), currently free of recurrent cancer and without a diagnosis of a cognitive disorder, were compared to matched healthy controls (N = 10). All subjects were imaged at rest with [(18)F]fluorodeoxyglucose. Images were analyzed semi-quantitatively using the Alzheimer's Discrimination Tool and a volume of interest-based approach derived from co-registered magnetic resonance imaging.

RESULTS

Relative [(18)F]fluorodeoxyglucose uptake (normalized to global) was significantly lower in the survivors compared with control subjects in bilateral orbital frontal regions, consistent with differences between the groups in cognition and executive function (i.e., Trail Making Test, Part B and mini-mental state examination) and despite no significant differences with respect to age, education, intelligence, or working memory. None of the survivors and only one control manifested a global positron emission tomography score consistent with an Alzheimer's disease metabolic pattern.

CONCLUSION

Breast cancer survivors treated with chemotherapy may manifest long-term changes in brain glucose metabolism indicative of subtle frontal hypometabolism, a finding consistent with results from neuropsychological testing and other imaging modalities.

[18F]fluorodeoxyglucose uptake in atherosclerotic plaques is associated with reduced coronary flow reserve in mice

OBJECTIVES

Coronary microvascular dysfunction, observed as impaired coronary vasodilator capacity, is an early manifestation of coronary artery disease. Inflammation plays an important role in different stages of atherogenesis. To study the role of vessel wall inflammation in the development of coronary dysfunction, we compared [(18)F]fluorodeoxyglucose (FDG) uptake in the aorta and coronary flow reserve (CFR) in atherosclerotic mice.

METHODS

We studied healthy young C57BL/6 mice fed a normal diet (n = 7) as well as hypercholesterolemic low-density lipoprotein receptor-disrupted/apolipoprotein B100-expressing (LDLR(-/-)ApoB(100/100)) mice (n = 15) and hypercholesterolemic and diabetic LDLR(-/-)ApoB(100/100)insulinlike growth factor II-overexpressing mice (n = 14) fed a western-type diet, aged 4 to 6 months. Doppler sonography was used to measure CFR as the ratio of coronary flow velocity during isoflurane-induced hyperemia and at rest. Uptake of [(18)F]FDG into the aorta was measured by autoradiography of tissue sections.

RESULTS

Histologic sections showed extensive atherosclerosis in the aorta, but coronary arteries were not obstructed. Both hyperemic coronary flow velocity and CFR were reduced (P < .05) in hypercholesterolemic mice with and without diabetes in comparison to healthy young C57BL/6 controls. Among hypercholesterolemic mice, both hyperemic flow velocity and CFR inversely correlated with atherosclerotic plaque [(18)F]FDG uptake in the aorta (r = -0.73; P < .001; r = -0.63; P = .001, respectively). In a multivariate analysis, including animal weight, aortic plaque burden, plasma glucose, plasma cholesterol, and [(18)F]FDG uptake in atherosclerotic plaques, only [(18)F]FDG uptake remained an independent predictor of reduced CFR (β = 0.736; P = .001).

CONCLUSIONS

The inflammatory activity in atherosclerotic plaques of the aorta independently predicts reduced CFR in atherosclerotic mice without obstructive coronary artery disease. This finding suggests that atherosclerotic inflammation contributes to coronary dysfunction.

Role of [18F]fluorodeoxyglucose positron emission tomography-computed tomography, sonography, and sonographically guided fine-needle aspiration biopsy in the diagnosis of axillary lymph nodes in patients with breast cancer: comparison of diagnostic performance

OBJECTIVES

The aim of this study was to compare the diagnostic performance of [(18)F]fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) with that of sonography and sonographically guided fine-needle aspiration (FNA) for determining the preoperative axillary lymph node (ALN) status and to evaluate the factors related to false-negative PET-CT, sonographic, and FNA results in ALN staging of invasive ductal carcinoma.

METHODS

From March 2009 to July 2012, 226 patients had a diagnosis of primary breast cancer. Among these patients, 107 constituted the study population after exclusion of transferred patients and patients with breast cancer other than invasive ductal carcinoma. The diagnostic performance of the modalities was compared with pathologic reports. Univariate and multivariate analyses were used to evaluate the relationship between clinicopathologic factors (symptoms, T stage, hormone receptors, and histologic grade), false-negative results, and true-negative results on PET-CT, sonography, and FNA.

RESULTS

Of the 107 patients, 45 (42.1%) had positive results on final pathologic analysis of ALNs. Sonographically guided FNA had a significantly higher specificity, positive predictive value, accuracy, and area under the receiver operating characteristic curve than sonography and PET-CT (P < .01). When sonography and PET-CT were combined, the sensitivity was significantly improved (P = .019) compared with sonography alone. When FNA and PET-CT were combined, the sensitivity and negative predictive value were significantly increased compared with each modality (P < .01).

CONCLUSIONS

Sonographically guided FNA was found to be an excellent diagnostic tool for preoperative evaluation of the ALN status. To obviate the step of sentinel lymph node biopsy for determining the ALN status, combined evaluation of ALNs by these modalities may be more complementary than the use of a single modality.

Evaluation of the inflammatory response in a two-hit acute lung injury model using [18F]FDG microPET

The aim of this study was to investigate whether a two-hit acute lung injury (ALI) model is better than a one-hit model in simulating ALI, and to evaluate the inflammatory response in the lungs in these two models using micro-positron emission tomography (microPET) with [¹⁸F]fluorodeoxyglucose (FDG). Sprague Dawley rats were divided into four groups; rats in the lipopolysaccharide (LPS; n=10) and LPS-HCl (n=10) groups were challenged by the intraperitoneal administration of 5 mg/kg LPS, while rats in the normal saline (NS; n=3) and HCl (n=10) groups received the same volume of normal saline solution. Sixteen hours following the administration, the rats in the HCl and LPS-HCl groups received an acid instillation (IT) of 0.5 ml/kg HCl (pH=1.2), while the rats in the remaining two groups received the same volume of normal saline solution. The mean arterial blood pressure (MAP) and blood gas concentrations were measured in all four groups. MicroPET was performed 4 h following HCl IT and the lungs were excised for histopathological examination. The rats in the LPS-HCl group exhibited a higher arterial PaO₂ and a lower arterial PaCO₂ compared with the rats in the remaining groups. The MAP decreased markedly in the LPS-HCl group, but remained stable in the LPS, HCl and NS groups. MicroPET results identified that the region of interest ratio in the LPS-HCl group (9.00±1.41) was significantly higher compared with those in the LPS (4.01±0.60) and HCl (3.33±0.55) groups (P<0.01). In addition, histological examination showed that the mean lung injury score in the LPS-HCl group (12.70±0.95) was significantly higher compared with those in the HCl (8.40±1.26) and LPS (7.00±0.82) groups (P<0.01). The present study demonstrates that LPS pretreatment significantly magnifies and prolongs the inflammatory response to subsequent acid IT in the lungs. Moreover, it is simpler to induce ALI using the two-hit model than with the one-hit model, and [¹⁸F]FDG microPET is a useful tool for evaluating the inflammatory reaction during ALI.

Clinical importance of [18F]fluorodeoxyglucose positron emission tomography/computed tomography in the management of patients with bronchoalveolar carcinoma: Role in the detection of recurrence

[¹⁸F]fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) has been reported to have a low sensitivity in the initial diagnosis of bronchoalveolar carcinoma (BAC) due to BAC’s low metabolic activity. The aim of this study was to assess the value of [¹⁸F]FDG-PET/CT in the detection of BAC recurrence. Between February 2007 and September 2011, the [¹⁸F]FDG-PET/CT scans that were performed on patients with known, histologically proven BAC were studied. A total of 24 [¹⁸F]FDG-PET/CT scans were performed in 22 patients, including 16 males and 6 females, with a mean age of 65±9 years. Among the scans, 15 were performed to assess for possible recurrence with equivocal findings in conventional imaging methods and 9 for restaging post-therapy. In all cases conventional imaging studies (CT and MRI) were performed 5–30 days prior to PET/CT. Among the 24 [¹⁸F]FDG-PET/CT scans, 18 were positive and 6 negative. Among the 15 [¹⁸F]FDG-PET/CT scans performed for suspected recurrence, 34 lesions were detected and the mean maximum standardized uptake value (SUVmax) was 6.8±3.26. In nine scans, upstaging was observed, while two were in agreement with the findings of the conventional modalities. A greater number of lesions were detected in two scans and fewer lesions were detected in one, with no change in staging. Only one scan was negative. By contrast, in patients examined for restaging, there were only five lesions with a mean SUVmax of 4.86±3.18. Agreement between the findings of [¹⁸F]FDG-PET/CT and the conventional modalities was observed in 8 out of 9 cases. Although [¹⁸F]FDG-PET/CT has been reported to have a low sensitivity in the initial diagnosis of BAC, the present results indicate that when there is recurrence, the lesions become [¹⁸F]FDG avid. [¹⁸F]FDG-PET/CT may provide further information in patients evaluated for recurrence and thus improve patient management.