Detection of bone metastases in patients with prostate cancer by <Superscript>18</Superscript>F fluorocholine and <Superscript>18</Superscript>F fluoride PET–CT: a comparative study

Purpose  The aim of this prospective study was to compare the potential value of ¹⁸F fluorocholine (FCH) and ¹⁸F fluoride positron emission tomography (PET)–CT scanning for the detection of bony metastases from prostate cancer. Methods  Thirty-eight men (mean age, 69 ± 8 years) with biopsy-proven prostate cancer underwent both imaging modalities within a maximum interval of 2 weeks. Seventeen patients were evaluated preoperatively, and 21 patients were referred for post-operative evaluation of suspected recurrence or progression based on clinical algorithms. The number, sites and morphological patterns of bone lesions on ¹⁸F FCH and ¹⁸F fluoride PET–CT were correlated: Concordant lesions between the two modalities with corresponding changes on CT were considered to be positive for malignancy; discordant lesions were verified by follow-up examinations. The mean follow-up interval was 9.1 months. Results  Overall, 321 lesions were evaluated in this study. In a lesion-based analysis, a relatively close agreement was found between these two imaging modalities for detection of malignant bone lesions (kappa = 0.57), as well as in a patient-based analysis (kappa = 0.76). Sixteen malignant sclerotic lesions with a high density were negative in both ¹⁸F FCH and ¹⁸F fluoride PET–CT [mean Hounsfield unit (HU), 1,148 ± 364]. There was also a significant correlation between tracer intensity by SUV and density of sclerotic lesions by HU both in ¹⁸F FCH PET–CT (r = −0.28, p < 0.006) and ¹⁸F fluoride PET–CT (r = −0.20, p < 0.05). The sensitivity, specificity and accuracy of PET–CT in the detection of bone metastases in prostate cancer was 81%, 93% and 86% for ¹⁸F fluoride, and 74% (p = 0.12), 99% (p = 0.01) and 85% for FCH, respectively. ¹⁸F FCH PET–CT led to a change in the management in two out of 38 patients due to the early detection of bone marrow metastases. ¹⁸F fluoride PET–CT identified more lesions in some patients when compared with ¹⁸F FCH PET–CT but did not change patient management. Conclusion  FCH PET–CT may be superior for the early detection (i.e. bone marrow involvement) of metastatic bone disease. In patients with FCH-negative suspicious sclerotic lesions, a second bone-seeking agent (e.g. ¹⁸F fluoride) is recommended. ¹⁸F fluoride PET–CT demonstrated a higher sensitivity than ¹⁸F FCH PET–CT, but the difference was not statistically significant. Furthermore, ¹⁸F fluoride PET could be also negative in highly dense sclerotic lesions, which presumably reflects the effect of treatment. It will be important to clarify in future studies whether these lesions are clinically relevant when compared with metabolically active bone metastases.     

The use of <Superscript>18</Superscript>F-FDG PET/CT in colorectal liver metastases—comparison with CT and liver MRI

PURPOSE: We compared 18-fluoro-2-deoxyglucose ((18)F-FDG) positron emission tomography-CT (PETCT) with contrast-enhanced whole-body CT (ceCT) in identifying extrahepatic disease and with manganese dipyridoxyl diphosphate (Mn-DPDP) liver MRI for liver metastases in patients with colorectal liver metastases being considered for surgery. METHODS: Sixty-five patients (median age 65 years; 42 men) with colorectal cancer and known or suspicious liver metastases and who underwent a PETCT, ceCT and Mn-DPDP MRI were identified. Results were retrospectively reviewed for extrahepatic disease on PETCT and ceCT, and for the presence and number of liver metastases on PETCT and Mn-DPDP MRI. Proof of metastases was based on histopathology or clinical/imaging follow-up, demonstrating disease progression or response. RESULTS: PETCT identified unexpected extrahepatic disease not detected on ceCT, leading to change in surgical management in 17%. There were three other false-positive cases on PETCT. For liver metastases on a per-patient basis, the sensitivity and specificity of both PETCT and Mn-DPDP MRI were 98% and 100%, respectively. On a per-lesion basis, PETCT and MRI were discordant in 15% (10/66 scans). MRI correctly identified more sub-centimeter metastases in eight scans. PETCT correctly identified more metastases in one case and confirmed disease in one equivocal MRI. CONCLUSION: PETCT has incremental benefit over conventional ceCT in identifying extrahepatic disease in metastatic colorectal cancer. PETCT has high sensitivity and specificity for the presence of liver metastases and should be included early in initial pre-surgical evaluation and could potentially guide the use of Mn-DPDP MRI. However, Mn-DPDP MRI is superior for small liver metastases and remains a prerequisite for surgical planning in patients with confined liver metastases.     

1-[<Superscript>11</Superscript>C]-acetate PET imaging in head and neck cancer—a comparison with <Superscript>18</Superscript>F-FDG-PET: implications for staging and radiotherapy planning

Purpose The aim of this study was to evaluate the feasibility of using 1-[¹¹C]-acetate positron emission tomography (ACE-PET) to detect and delineate the gross tumour volume of head and neck cancer before radiotherapy, and to compare the results with those obtained using ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) PET. Methods Ten patients with histologically verified squamous cell carcinoma were investigated by FDG-PET and dynamic ACE-PET prior to radiotherapy. The two scans were performed on the same day or on consecutive days, except in one patient in whom they were done 5 days apart. Diagnostic CT or MRI was performed in all patients. The image data sets were analysed both visually and semi-quantitatively. All primary tumours and metastases were delineated automatically by using the 50% threshold of maximum radioactivity corrected for background. The mean standardised uptake value (SUV) and the tumour volumes were evaluated and compared. Results All ten primary tumours were detected by ACE-PET, while nine primaries were detected by FDG-PET and CT and/or MRI. The ACE SUV tended to be lower than the FDG SUV (5.3±2.7 vs 9.6±7.0, p=0.07). The tumour volumes delineated with ACE were on average 51% larger than the FDG volumes (p<0.05). ACE-PET identified 20/21 lymph node metastases, while only 13/21 lesions were detected by FDG-PET and 16/21 lesions by CT or MRI. Conclusion ACE-PET appears promising for the staging of head and neck cancer. The biological information provided by both FDG and ACE must be carefully validated before it can be used in clinical routine for radiation treatment planning. More studies are needed to evaluate the differences in volumes and to confirm the clinical potential of both FDG and ACE-PET, especially in radiotherapy. The first two authors contributed equally to this paper.     

The appearance of Mazabraud’s syndrome on <Superscript>18</Superscript>F-FDG PET/CT

Mazabraud’s syndrome is a rare disorder, the main characteristics of which are fibrous dysplasia of bone associated with intramuscular myxomas. The metabolic characteristics of intramuscular myxomas, associated with fibrous dysplasia, have not previously been described with ¹⁸F-FDG-PET. Our case demonstrates that there is low, but not insignificant uptake associated with these intramuscular myxomas, with a standardized uptake value (SUV) range between 1.3 and 2.6. As such, this entity merits consideration when evaluating hypoattenuating intramuscular masses, particularly in the context of fibrous dysplasia.     

Does <Superscript>18</Superscript>F-FDG PET/CT add diagnostic accuracy in incidentally identified non-secreting adrenal tumours?

Purpose  The widespread use of high-resolution cross-sectional imaging such as computed tomography (CT) and magnetic resonance imaging (MRI) for the investigation of the abdomen is associated with an increasing detection of incidental adrenal masses. We evaluated the ability of ¹⁸F-fluorodeoxyglucose positron emission tomography to distinguish benign from malignant adrenal masses when CT or MRI results had been inconclusive. Methods  We included only patients with no evidence of hormonal hypersecretion and no personal history of cancer or in whom previously diagnosed cancer was in prolonged remission. PET/CT scans were acquired after 90 min (mean, range 60–140 min) after FDG injection. The visual interpretation, maximum standardised uptake values (SUVmax) and adrenal compared to liver uptake ratio were correlated with the final histological diagnosis or clinico-radiological follow-up when surgery had not been performed. Results  Thirty-seven patients with 41 adrenal masses were prospectively evaluated. The final diagnosis was 12 malignant, 17 benign tumours, and 12 tumours classified as benign on follow-up. The visual interpretation was more accurate than SUVmax alone, tumour diameter or unenhanced density, with a sensitivity of 100% (12/12), a specificity of 86% (25/29) and a negative predictive value of 100% (25/25). The use of 1.8 as the threshold for tumour/liver SUVmax ratio, retrospectively established, demonstrated 100% sensitivity and specificity. Conclusion  FDG PET/CT accurately characterises adrenal tumours, with an excellent sensitivity and negative predictive values. Thus, a negative PET may predict a benign tumour that would potentially prevent the need for surgery of adrenal tumours with inconclusive conventional imaging.     

<Superscript>68</Superscript>Ga-DOTATATE PET–CT imaging in carotid body paragangliomas

Objective

The aim of this study was to present our experience in the baseline evaluation of carotid body paragangliomas (CBP) with ⁶⁸Ga-DOTATATE PET–CT.

Methods

Five patients (4F, 1M; age 24–73 years) with CBPs who underwent ⁶⁸Ga-DOTATATE PET–CT scan before the treatment were evaluated retrospectively. PET–CT images were analyzed visually as well as semiquantitatively, with measurement of maximum standardized uptake value (SUV_max).

Results

All patients had unilateral CBP lesion, showed intense ⁶⁸Ga-DOTATATE uptake in PET–CT. Additionally, ⁶⁸Ga-DOTATATE avid lesions were found in two patients. One of them had focal intense uptake in thyroid gland and frontal cerebrum. The other one had intense uptake in bone and adrenal mass. Four patients were operated for unilateral primary CBP. Last patient was treated with peptide receptor radionuclide therapy (¹⁷⁷Lu-DOTATATE) for both metastatic pheochromocytoma and CBP.

Conclusions

⁶⁸Ga-DOTATATE PET–CT is a valuable imaging modality for staging of CBPs, detecting unknown lesions and changing the management of patients. It is also useful in demonstrating expression of SSTRs for PRRT opportunity.

     

<Superscript>18</Superscript>p-FDG PET is superior to<Superscript>67</Superscript>Ga SPECT in the staging of non-Hodgkin’s lymphoma

OBJECTIVE: Our study aims to compare diagnostic accuracy between 18F-FDG PET and 67Ga SPECT in the staging of non-Hodgkin's lymphoma. METHODS: Twenty-eight patients with non-Hodgkin's lymphoma, underwent 18F-FDG PET, 67Ga SPECT and CT for the pretreatment staging of malignant lymphoma between August 1999 and March 2002. 18F-FDG PET imaging was obtained 60 minutes after the intravenous administration of 185 MBq of 18F-FDG. 67Ga SPECT imaging was obtained 2 days after the intravenous administration of 148 MBq of 67Ga. 18F-FDG PET and 67Ga SPECT were performed within one month. Both imagings were performed on the area from the neck to the pelvis. The 18F-FDG PET and 67Ga SPECT findings were compared with the CT findings and the clinical course. RESULTS: Sixty-six nodal lesions were clinically confirmed. Of these, 32 were identified by both 18F-FDG PET and 67Ga SPECT. The remaining 34 lesions were identified only by 18F-FDG PET. The mean (+/- SD) sizes' of the nodes were 34.7 +/- 32.4 mm for 18F-FDG-positive and 67Ga-positive lesions and 15.7 +/- 8.3 mm for 18F-FDG-positive and 67Ga-negative lesions (p < 0.001). Of the 23 extranodal lesions, 12 were identified by both 18F-FDG PET and 67Ga SPECT, whereas 6 lesions were identified by only 18F-FDG PET. Five lesions were not identified by either technique. No 18F-FDG-negative but 67Ga-positive nodal or extranodal lesions were observed. The difference in findings between the two studies is related to the difference in the size but not in the histology or site of the lesions. CONCLUSION: 18F-FDG PET detected significantly more lesions particularly small lesions than 67Ga SPECT. Thus, 18F-FDG PET is considered to be superior to 67Ga SPECT in the staging of non-Hodgkin' s lymphoma.     

Groove Pancreatitis Masquerading as Pancreatic Carcinoma—Detected on <Superscript>18</Superscript>F-FDG PET/CT

Groove pancreatitis is a rare form of chronic pancreatitis that affects the groove area adjacent to the second part of the duodenum. Clinical and biochemical features often overlap with other subsets of chronic pancreatitis, while the imaging features resemble that of carcinoma of the head of pancreas. We present a 38-year-old man with abdominal pain, nausea, vomiting, and loss of weight who underwent ¹⁸F-FDG PET/CT to rule out a pancreatic malignancy. PET/CT imaging features of groove pancreatitis are distinct from the other subsets of chronic pancreatitis, such as alcoholic and autoimmune pancreatitis, and helpful in the diagnosis and planning further management of the patient.     

<Superscript>18</Superscript>F-FDG PET for the lymph node staging of non-small cell lung cancer in a tuberculosis-endemic country: <Emphasis Type="Italic">Is dual time point imaging worth the effort?</Emphasis>

PURPOSE: This study was to compare (18)F-FDG positron emission tomography (PET) with thoracic contrast-enhanced CT (CECT) in the ability of lymph node (LN) staging non-small cell lung cancer (NSCLC) in a tuberculosis-prevalent country. The usefulness of dual time point PET imaging (DTPI) in NSCLC nodal staging was also evaluated. METHODS: We reviewed 96 NSCLC patients (mean age, 65.3 +/- 11.7 years) who had received PET studies before their surgery. DTPI were performed on 37 patients (mean age, 64.8 +/- 12.2 years) who received an additional scan of thorax 3 h after tracer injection. The accuracies of nodal staging by CECT and PET were evaluated according to final histopathology of hilar and mediastinal LN resected by surgery. RESULTS: The accuracy for nodal staging by CECT was 65.6% and that by PET was 82.3% (p < 0.05). Six patients were over-staged and 11 were under-staged by PET. Tuberculosis (n = 3, 50%) were mostly responsible for false-positive, while small tumor foci (n = 7, 63.6%) were mostly accountable for false-negative. For the 37 patients with DTPI, 45 min standardized uptake value (SUV) and 3 h SUV for negative LNs are significantly lower than those for positive LNs (p < 0.0001). Nevertheless, the retention index (RI) showed no significant difference between these two groups. CONCLUSIONS: Our study demonstrates that PET is more accurate than CECT in LN staging NSCLC patients in Taiwan where TB is still prevalent. Semi-quantitative SUV method or DTPI with RI does not result in better diagnostic accuracy than visual analysis of PET images.     

<Superscript>18</Superscript>F–FDG-PET/CT for systemic staging of patients with newly diagnosed ER-positive and HER2-positive breast cancer

Objectives

This study assesses ¹⁸F–FDG-PET/CT for patients with newly diagnosed estrogen receptor-positive/human epidermal growth factor receptor-negative (ER+/HER2-) and human epidermal growth factor receptor-positive (HER2+) breast cancer.

Methods

In this Institutional Review Board-approved retrospective study, our Healthcare Information System was screened for patients with ER+/HER2- and HER2+ breast cancer who underwent ¹⁸F–FDG-PET/CT prior to systemic or radiation therapy. The initial stage was determined from mammography, ultrasound, magnetic resonance imaging, and/or surgery.¹⁸F–FDG-PET/CT was evaluated to identify unsuspected extra-axillary regional nodal and distant metastases. The proportion of patients upstaged overall and stratified by stage and receptor phenotypes was calculated along with confidence intervals (CI).

Results

A total of 238 patients with ER+/HER2- and 245 patients with HER2+ who met inclusion criteria were evaluated. For patients with ER+/HER2-breast cancer, ¹⁸F–FDG-PET/CT revealed unsuspected distant metastases in 3/71 (4%) initial stage IIA, 13/95 (14%) stage IIB, and 15/57 (26%) stage III. For patients with HER2+ breast cancer, ¹⁸F–FDG-PET/CT revealed unsuspected distant metastases in 3/72 (4%) initial stage IIA, 13/93 (14%) stage IIB, and 13/59 (22%) stage III. The overall upstaging rate for IIB was 14% (95% confidence interval (CI): 9–20%).

Conclusions

¹⁸F–FDG-PET/CT revealed distant metastases in 14% (95% CI: 9–20%) of patients with stage IIB ER+/HER2- and HER2+ breast cancer, which is similar to upstaging rates previously seen in patients with stage IIB triple-negative breast cancer (15%, 95% CI: 9–24%). The detection of unsuspected distant metastases in these patients alters treatment and prognosis. NCCN guidelines should consider adding patients with stage IIB breast cancer for consideration of systemic staging with ¹⁸F–FDG-PET/CT at the time of initial diagnosis.

     

Unusual Horner’s Syndrome in Recurrent Breast Cancer: Evaluation Using <Superscript>18</Superscript>F-FDG PET/CT

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a widely used imaging modality in the initial diagnosis of cancer, treatment response evaluation and detection of recurrence. Herein, we present the case of a 39-year-old female who presented right ptosis on the follow-up of breast cancer after surgery. Clinicians suspected Horner’s syndrome, and the patient underwent FDG PET/CT for the evaluation of recurrence that could cause Horner’s syndrome. FDG PET/CT demonstrated a focal hypermetabolic lesion in the right cervicothoracic junction area, corresponding to the preganglionic cervical sympathetic trunk. A subsequent needle biopsy was done, and the lesion was confirmed as metastatic ductal carcinoma. In this case, we could detect the exact location of the recurring lesion that caused Horner’s syndrome using FDG PET/CT.     

Do androgens control the uptake of <Superscript>18</Superscript>F-FDG, <Superscript>11</Superscript>C-choline and <Superscript>11</Superscript>C-acetate in human prostate cancer cell lines?

Purpose  

The aim of this study was to evaluate the impact of androgen ablation therapy in different prostate cancer (PCa) cell lines—reflecting different stages of the disease—on ¹⁸F-fluorodeoxyglucose (FDG), ¹¹C-choline and ¹¹C-acetate uptake.     

Hybrid <Superscript>18</Superscript>F–FDG PET/MRI might improve locoregional staging of breast cancer patients prior to neoadjuvant chemotherapy

Purpose

Our purpose in this study was to assess the added clinical value of hybrid ¹⁸F–FDG-PET/MRI compared to conventional imaging for locoregional staging in breast cancer patients undergoing neoadjuvant chemotherapy (NAC).

Methods

In this prospective study, primary invasive cT2-4 N0 or cT1-4 N+ breast cancer patients undergoing NAC were included. A PET/MRI breast protocol was performed before treatment. MR images were evaluated by a breast radiologist, blinded for PET images. PET images were evaluated by a nuclear physician. Afterwards, a combined PET/MRI report was written. PET/MRI staging was compared to conventional imaging, i.e., mammography, ultrasound and MRI. The proportion of patients with a modified treatment plan based on PET/MRI findings was analyzed.

Results

A total of 40 patients was included. PET/MRI was of added clinical value in 20.0% (8/40) of patients, changing the treatment plan in 10% and confirming the malignancy of suspicious lesions on MRI in another 10%. In seven (17.5%) patients radiotherapy fields were extended because of additional or affirmative PET/MRI findings being lymph node metastases (n = 5) and sternal bone metastases (n = 2). In one (2.5%) patient radiotherapy fields were reduced because of fewer lymph node metastases on PET/MRI compared to conventional imaging. Interestingly, all treatment changes were based on differences in number of lymph nodes suspicious for metastasis or number of distant metastasis, whereas differences in intramammary tumor extent were not observed.

Conclusion

Prior to NAC, PET/MRI shows promising results for locoregional staging compared to conventional imaging, changing the treatment plan in 10% of patients and potentially replacing PET/CT or tissue sampling in another 10% of patients.

     

<Superscript>125</Superscript>I brachytherapy in younger prostate cancer patients

Purpose

To evaluate local recurrence in younger men treated with low-dose-rate (LDR) ¹²⁵I brachytherapy (BT) for localized prostate cancer.

Patients and methods

A total of 192 patients (≤65-years-old) were treated with LDR ¹²⁵I-BT ± hormone therapy. Local failure was defined as any prostate-specific antigen (PSA) rise leading to salvage treatment or biochemical failure according to the Phoenix definition. A bounce was defined as a rise in the nadir of ≥0.2?ng/mL followed by spontaneous return. Proportions were compared using Fisher’s exact tests; continuous variables using the unpaired t-test or its non-parametric equivalent. Cox proportional hazards models were applied for multivariable survival analysis.

Results

Median follow-up was 66 months. The 5?year local recurrence-free survival was 96.1%. Biopsy-proven local recurrence developed in 13 patients, 4 had a Phoenix-defined recurrence at the last follow-up. Androgen deprivation therapy was started in 1 patient without proven recurrence. Univariable risk factors for local recurrence were: at least 50% positive biopsies, intermediate risk, treatment with neoadjuvant hormone therapy, low preimplantation volume receiving 100% of the prescribed dose, and no bounce development. Hormone-naïve patients not attaining a PSA value <0.5?ng/mL during follow-up also had a higher risk of local recurrences. Cox regression demonstrated that the variables “at least 50% positive biopsies” and “bounce” significantly impacted local failure (hazard ratio, HR 1.02 and 11.59, respectively). A bounce developed in 70 patients (36%). Younger patients and those treated with a lower activity per volume had a higher chance of developing a bounce in the Cox model (HR 0.99 and 0.04, respectively).

Conclusion

For younger men, LDR BT is a valid primary curative treatment option in low-risk and is to consider in intermediate-risk localized prostate cancer.

     

Imaging with <Superscript>124</Superscript>I in differentiated thyroid carcinoma: is PET/MRI superior to PET/CT?

Purpose

The aim of this study was to compare integrated PET/CT and PET/MRI for their usefulness in detecting and categorizing cervical iodine-positive lesions in patients with differentiated thyroid cancer using ¹²⁴I as tracer.

Methods

The study group comprised 65 patients at high risk of iodine-positive metastasis who underwent PET/CT (low-dose CT scan, PET acquisition time 2 min; PET/CT₂) followed by PET/MRI of the neck 24 h after ¹²⁴I administration. PET images from both modalities were analysed for the numbers of tracer-positive lesions. Two different acquisition times were used for the comparisons, one matching the PET/CT₂ acquisition time (2 min, PET/MRI₂) and the other covering the whole MRI scan time (30 min, PET/MRI₃₀). Iodine-positive lesions were categorized as metastasis, thyroid remnant or inconclusive according to their location on the PET/CT images. Morphological information provided by MRI was considered for evaluation of lesions on PET/MRI and for volume information.

Results

PET/MRI₂ detected significantly more iodine-positive metastases and thyroid remnants than PET/CT₂ (72 vs. 60, p?=?0.002, and 100 vs. 80, p?=?0.001, respectively), but the numbers of patients with at least one tumour lesion identified were not significantly different (21/65 vs. 17/65 patients). PET/MRI₃₀ tended to detect more PET-positive metastases than PET/MRI₂ (88 vs. 72), but the difference was not significant (p?=?0.07). Of 21 lesions classified as inconclusive on PET/CT, 5 were assigned to metastasis or thyroid remnant when evaluated by PET/MRI. Volume information was available in 34 % of iodine-positive metastases and 2 % of thyroid remnants on PET/MRI.

Conclusions

PET/MRI of the neck was found to be superior to PET/CT in detecting iodine-positive lesions. This was attributed to the higher sensitivity of the PET component, Although helpful in some cases, we found no substantial advantage of PET/MRI over PET/CT in categorizing iodine-positive lesions as either metastasis or thyroid remnant. Volume information provided by MRI for some iodine-positive lesions might be useful in dosimetry.

     

Is <Superscript>18</Superscript>F-FDG PET/CT useful for the differential diagnosis of solitary pulmonary nodules in patients with idiopathic pulmonary fibrosis?

Objective

Idiopathic pulmonary fibrosis (IPF) is associated with an increased incidence of lung cancer, but patients with IPF often have poor pulmonary function and are vulnerable to pneumothorax and so using an invasive procedure to diagnose a single nodule detected on chest CT risks a critical adverse outcome. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) is recognized to be useful for differentiating between benign and malignant solitary pulmonary nodules (SPN) in patients without IPF, but its diagnostic accuracy has not been investigated in patients with IPF. In this study, therefore, we investigated whether ¹⁸F-FDG PET/CT is useful for the differential diagnosis of SPNs in patients with IPF.

Methods

From the IPF patient cohort of our institution, we retrospectively reviewed 55 patients (54 men, 1 woman; age 67.8?±?7.6 years) with an SPN sized 8–30 mm (mean 18.5?±?5.7 mm) who underwent chest CT followed by ¹⁸F-FDG PET/CT between April 2004 and March 2016. The ¹⁸F-FDG uptake of the SPN was analyzed visually and semiquantitatively, and these determinations were compared with the final diagnosis obtained by pathology (n?=?52) or imaging follow-up (n?=?3).

Results

The final diagnoses showed that 41 (75%) of the SPNs were malignant (21 squamous cell carcinomas, 9 adenocarcinomas, 5 small-cell carcinomas, 4 mixed-type carcinomas, 1 large-cell neuroendocrine carcinoma, and 1 sarcoid carcinoma) and 14 (25%) were benign. The determination of malignant SPNs by visual analysis of the PET/CT images had a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 98, 86, 95, and 92%, respectively. The semiquantitative analysis using a maximum standardized uptake value of 2.0 as the cut-off had a sensitivity, specificity, PPV, and NPV of 95, 93, 98, and 87%, respectively.

Conclusions

¹⁸F-FDG PET/CT is useful for differentiating benign and malignant SPNs in patients with IPF, as it is for patients without IPF.

     

Detectability of residual invasive bladder cancer in delayed <Superscript>18</Superscript>F-FDG PET imaging with oral hydration using 500 mL of water and voiding-refilling

Objective

2-Fluorine-18-fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET) imaging is not considered useful for assessing bladder cancer due to the physiological uptake of ¹⁸F-FDG in the bladder. Despite reports of the detection of bladder cancer by washing out ¹⁸F-FDG from the bladder, such methods are invasive and impractical in the routine practice. The purpose of this study was to evaluate prospectively the utility of oral hydration with 500 mL of water and voiding-refilling, a minimally invasive method that we introduced to enable detection of residual invasive bladder cancer on delayed ¹⁸F-FDG PET imaging.

Methods

From January 2015 to December 2017, 267 consecutive patients with bladder cancer underwent ¹⁸F-FDG PET/computed tomography scans. Among these patients, 25 (19 men and 6 women; mean age, 72.0?±?11.3 years) were newly diagnosed as having muscle-invasive bladder cancer by transurethral resection of bladder tumor and T3b or T4 by magnetic resonance imaging (MRI). All patients were orally hydrated with only 500 mL of water and were then instructed to void frequently for 60 min before early ¹⁸F-FDG PET imaging. After the scans, they were instructed to hold their urine for 60 min. Then, delayed imaging was performed. Two radiologists evaluated the early and delayed ¹⁸F-FDG PET images to determine whether residual invasive bladder cancer could be detected. The maximum standardized uptake values (SUVmax) of the bladder urine and residual tumor site were also measured on early and delayed images. The maximum diameter of the primary bladder tumor was measured on MRI.

Results

The sensitivity for detecting residual invasive bladder cancer on early and delayed imaging were 24.0 and 92.0%, respectively (P?<?0.001). The SUVmax of the bladder urine on the early and delayed imaging were 34.7?±?29.7 and 16.0?±?10.7 (mean?±?SD), respectively. The SUVmax of the residual tumor site on the early and delayed imaging were range 15.65–30.83 and 10.06–45.70, respectively.

Conclusion

Delayed ¹⁸F-FDG PET imaging with oral hydration using only 500 mL of water and voiding-refilling is useful for detecting residual invasive bladder cancer.