<Superscript>18</Superscript>F-fluorodeoxyglucose positron emission tomography in uterine carcinosarcoma

Purpose Uterine carcinosarcomas clinically confined to the uterus usually harbor occult metastases. We conducted a pilot study to evaluate the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in uterine carcinosarcoma. Methods Patients with histologically confirmed uterine carcinosarcoma were enrolled. Abdominal and pelvic magnetic resonance imaging (MRI)/whole-body computed tomography (CT) scan, and whole-body ¹⁸F-FDG PET or PET/CT were undertaken for primary staging, evaluating response, and restaging/post-therapy surveillance. The clinical impact of ¹⁸F-FDG PET was determined on a scan basis. Results A total of 19 patients were recruited and 31 ¹⁸F-FDG PET scans (including 8 scans performed on a PET/CT scanner) were performed. Positive impacts of scans were found in 36.8% (7/19) for primary staging, 66.7% (2/3) for monitoring response, and 11.1% (1/9) for restaging/post-therapy surveillance. PET excluded falsely inoperable disease defined by MRI in two patients. Aggressive treatment applying to three patients with PET-defined resectable stage IVB disease seemed futile. Two patients died of disease shortly after salvage therapy restaged by PET. With PET monitoring, one stage IVB patient treated by targeted therapy only was alive with good performance. Using PET did not lead to improvement of overall survival of this series compared with the historical control (n = 35) (P = 0.779). Conclusions The preliminary results suggest that ¹⁸F-FDG PET is beneficial in excluding falsely inoperable disease for curative therapy and in making a decision on palliation for better quality of life instead of aggressive treatment under the guidance of PET. PET seems to have limited value in post-therapy surveillance or restaging after failure.     

<Superscript>18</Superscript>F-FDG PET/CT detects Metastatic Renal Cell Carcinoma Masquerading as Primary Breast Malignancy

We present the case of a 36-year-old woman who underwent ¹⁸F-FDG PET/CT with suspicion of a primary breast malignancy. However, PET/CT detected an occult renal cell carcinoma with metastases to the thyroid, breast, lungs and lymph nodes. Thyroid and breast metastases are atypical metastatic sites of renal cell carcinoma. Breast metastases from extra mammary tissue are extremely rare, more so from renal cell carcinoma. Histopathologic confirmation of the breast lesions is imperative to avoid unnecessary mastectomy and imaging can help in raising the suspicion of metastatic involvement versus primary breast malignancy.     

Diagnostic impact of PET with <Superscript>18</Superscript>F-FDG, <Superscript>18</Superscript>F-DOPA and 3-<Emphasis Type="Italic">O</Emphasis>-methyl-6-[<Superscript>18</Superscript>F]fluoro-DOPA in recurrent or metastatic medullary thyroid carcinoma

Purpose In patients with medullary thyroid carcinoma (MTC), rising levels of the tumour markers calcitonin and CEA after primary surgery indicate tumour recurrence or metastases. The only chance of cure is the resection of localised tumour tissue. For positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and ¹⁸F-dihydroxyphenylalanine (¹⁸F-DOPA), sensitivities of 78% and 63% have been reported, but in a considerable percentage of MTC patients the source of tumour marker elevation is not detected. The aim of this retrospective data evaluation was to compare the value of PET with ¹⁸F-FDG, ¹⁸F-DOPA and the amino acid tracer 3-O-methyl-6-[¹⁸F]fluoro-DOPA (¹⁸F-OMFD) in the detection of MTC recurrence. Methods Fifteen patients with elevated calcitonin were investigated with PET as part of their individual clinical work-up. All patients underwent ¹⁸F-FDG PET and ¹⁸F-DOPA PET, and ten patients underwent ¹⁸F-OMFD PET. Results With ¹⁸F-FDG, seven patients showed foci in the neck, mediastinum, upper abdomen or bone. In seven patients, ¹⁸F-DOPA revealed suspicious foci; five of these seven patients showed partially corresponding uptake of ¹⁸F-FDG in the neck and mediastinum. Two of these patients underwent surgery and metastases were verified. With ¹⁸F-OMFD, a small focus in the liver was suspected in one patient without a correlate on ¹⁸F-FDG PET, ¹⁸F-DOPA PET or conventional imaging. Conclusion ¹⁸F-FDG and ¹⁸F-DOPA showed foci that were highly suspicious for local recurrence or metastasis of MTC, although histological verification in these patients with numerous previous surgical interventions was performed in only two patients. The amino acid tracer ¹⁸F-OMFD had no diagnostic impact in these patients.     

18F-氟代脱氧葡萄糖PET在肾恶性肿瘤中的应用

18F-氟代脱氧葡萄糖(18F-FDG)PET在肾恶性肿瘤中主要应用于原发肿瘤定性诊断和分期、肿瘤局部复发及远处转移病灶诊断等。PET检查对选择治疗方案的影响主要由于发现远处转移病灶和对病灶定性。并优于CT等常规检查。但18F-FDG PET对诊断原发性肾细胞癌敏感性低于CT,可能与肿瘤分级或某些特性有关。     

Usefulness of <Superscript>18</Superscript>F-FDG PET/CT to Detect Metastatic Mucinous Adenocarcinoma Within an Inguinal Hernia

Metastatic mucinous adenocarcinoma in an inguinal hernia is a rare disease and the image findings of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) are little known. Here, we introduce a 57-year-old man with metastatic mucinous adenocarcinoma in an inguinal hernia. On initial ¹⁸F-FDG PET/CT, hypermetabolism was observed in mucinous adenocarcinoma of the cecum, and adenocarcinomas of the transverse and ascending colon, respectively. Follow-up ¹⁸F-FDG PET/CT revealed newly developed multiple hypermetabolism in peritoneal seeding masses and nodules in the pelvic cavity and scrotum. Peritoneal carcinomatosis in the right pelvic side wall was extended to the incarcerated peritoneum and mesentery in the right inguinoscrotal hernia.¹⁸F-FDG PET/CT was useful to reveal unexpected peritoneal seeding within the inguinal hernia. Also, this case demonstrated that metastatic mucinous adenocarcinomas had variably intense FDG uptake.     

<Superscript>11</Superscript>C-methionine uptake in cerebrovascular disease: A comparison with<Superscript>18</Superscript>F-FDG PET and<Superscript>99m</Superscript>Tc-HMPAO SPECT

OBJECTIVES: Carbon-11-L-methyl-methionine (11C-methionine) has been reported to be useful for evaluating brain tumors, but several other brain disorders have also shown signs of high methionine uptake. We retrospectively evaluated the significance of 11C-methionine uptake in cerebrovascular diseases, and also compared our results with those for 18F-FDG PET and 99mTc-HMPAO SPECT. METHODS: Seven patients, including 3 patients with a cerebral hematoma and 4 patients with a cerebral infarction, were examined. All 7 patients underwent both 11C-methionine PET and 99mTc-HMPAO SPECT, and 6 of them underwent 18F-FDG PET. RESULTS: A high 11C-methionine uptake was observed in all 3 patients with cerebral hematoma. Increased 99mTc-HMPAO uptake was observed in 2 out of 3 patients, and all 3 patients had decreased 18F-FDG uptake. Of 4 patients with a cerebral infarction, high 11C-methionine uptake was observed in 3. Increased 99mTc-HMPAO uptake was also observed in one patient, whereas 3 patients had decreased 18F-FDG uptake. CONCLUSIONS: We should keep in mind that high 11C-methionine uptake is frequently observed in cerebrovascular diseases. CVD should therefore be included in the differential diagnosis when encounting patients with a high 11C-methionine uptake.     

Small Cell Carcinoma of the Gallbladder: 18F-FDG PET/CT Imaging Features—A Case Report

The diagnostic role of ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) for gallbladder small cell carcinoma has not been reported. A knowledge of the imaging characteristic features of this malignancy can be useful. Here we report a rare case of a patient who had various diagnostic imaging modalities, including ¹⁸F-FDG PET/CT.     

Opportunities for 2-[18F] Fluoro-2-Deoxy-D-Glucose PET/CT in Cervical-Vaginal Neuroendocrine Carcinoma: Case Series and Literature Review

Objective

Neuroendocrine cervical carcinoma is a rare subtype of cervical cancer. These tumors exhibit an aggressive behavior with early regional lymph node and distant metastases. The purpose of our study was to describe five cases of neuroendocrine cervical-vaginal carcinoma and to discuss the potential of the 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) scan for the detection of this rare malignancy.

Materials and Methods

Five cases of cervical-vaginal neuroendocrine tumor were retrospectively collected, during a two year (from September 2009 to August 2011) period in our hospital. The clinical staging distributions were International Federation of Gynecology and Obstetrics (FIGO) stage IB2 (1 of 5), stage IIA (3 of 5) and stage IVA (1 of 5).

Results

Two cases (cases 1 and 4) were restaged after ¹⁸F-FDG PET/CT scan in the initial staging process. Post-treatment ¹⁸F-FDG PET/CT scans, in three patients, revealed positive findings for tumor recurrence or lymph node metastases. Two patients (cases 2 and 3) died of tumor within two years.

Conclusion

¹⁸F-FDG PET/CT scan is a useful tool in cervical-vaginal neuroendocrine tumor. In its initial staging, the ¹⁸F-FDG PET/CT scan may help assess the possible nodal involvement or early hematogeneous spreading. We can also use the ¹⁸F-FDG PET/CT to detect local recurrence and to evaluate the treatment response after clinical manipulation.     

The role of <Superscript>18</Superscript>F-FDG PET in characterising disease activity in Takayasu arteritis

Takayasu arteritis (TA) is a rare, sporadic and chronic inflammatory arteritis, which predominantly affects the aorta and its branches. Diagnosis can be difficult and there are limitations to the current diagnostic work-up. By detecting areas of active glucose metabolism present in active vasculitis, imaging with fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) could potentially have a role in the management of TA. Our aim was to assess this role by reviewing 28 ¹⁸F-FDG PET scans performed on 18 patients suspected of having TA. All patients had full clinical and laboratory assessment, cross-sectional imaging and angiography, and 16/18 satisfied the American College of Rheumatologists criteria for TA. ¹⁸F-FDG PET achieved a sensitivity of 92%, a specificity of 100%, and negative and positive predictive values of 85% and 100% respectively in the initial assessment of active vasculitis in TA. We conclude that ¹⁸F-FDG PET can be used to diagnose early disease, to detect active disease (even within chronic changes) and to monitor the effectiveness of treatment.     

<Superscript>18</Superscript>F-FDG PET,genotype-corrected ACE and sIL-2R in newly diagnosed sarcoidosis

Purpose  Angiotensin-converting enzyme (ACE) and soluble interleukin-2 receptor (sIL-2R) are serological markers, widely used for determining sarcoidosis activity. ¹⁸F-FDG PET has proven to be a sensitive technique in the imaging of sarcoidosis. The aim of this study was to determine sensitivity of ¹⁸F-FDG PET, genotype-corrected ACE and sIL-2R in active sarcoidosis as well as their correlation. Methods  This retrospective study included 36 newly diagnosed, symptomatic sarcoidosis patients. ACE and sIL-2R levels were simultaneously obtained within 4 weeks of ¹⁸F-FDG PET. ACE was corrected for genotype and expressed as Z-score. ¹⁸F-FDG PET was visually evaluated and scored as positive or negative. Maximum and average standardized uptake values (SUV_max and SUV_avg) were compared with ACE and sIL-2R. Results   ¹⁸F-FDG PET was found positive in 34 of 36 patients (94%). Thirteen patients (36%) showed an increased ACE with the highest sensitivity found in patients with the I/I genotype (67%). Seventeen patients (47%) showed an increased sIL-2R. No correlation was found between SUV and ACE or sIL-2R. Increased ACE and sIL-2R correlated with a positive ¹⁸F-FDG PET in 12 patients (92%) and 16 patients (94%), respectively. Conclusion   ¹⁸F-FDG PET is a very sensitive technique to assess active sarcoidosis, in contrast with ACE and sIL-2R, suggesting a pivotal role for ¹⁸F-FDG PET in future sarcoidosis assessment.     

Usefulness of 18F-fluoride PET/CT in Breast Cancer Patients with Osteosclerotic Bone Metastases

Purpose

Bone metastasis is an important factor for the treatment and prognosis of breast cancer patients. Whole-body bone scintigraphy (WBBS) can evaluate skeletal metastases, and ¹⁸F-FDG PET/CT seems to exhibit high specificity and accuracy in detecting bone metastases. However, there is a limitation of ¹⁸F-FDG PET in assessing sclerotic bone metastases because some lesions may be undetectable. Recent studies showed that ¹⁸F-fluoride PET/CT is more sensitive than WBBS in detecting bone metastases. This study aims to evaluate the usefulness of ¹⁸F-fluoride PET/CT by comparing it with WBBS and ¹⁸F-FDG PET/CT in breast cancer patients with osteosclerotic skeletal metastases.

Materials and Methods

Nine breast cancer patients with suspected bone metastases (9 females; mean age ± SD, 55.6 ± 10.0 years) underwent ^99mTc-MDP WBBS, ¹⁸F-FDG PET/CT and ¹⁸F-fluoride PET/CT. Lesion-based analysis of five regions of the skeletons (skull, vertebral column, thoracic cage, pelvic bones and long bones of extremities) and patient-based analysis were performed.

Results

¹⁸F-fluoride PET/CT, ¹⁸F-FDG PET/CT and WBBS detected 49, 20 and 25 true metastases, respectively. Sensitivity, specificity, positive predictive value and negative predictive value of ¹⁸F-fluoride PET/CT were 94.2 %, 46.3 %, 57.7 % and 91.2 %, respectively. Most true metastatic lesions on ¹⁸F-fluoride PET/CT had osteosclerotic change (45/49, 91.8 %), and only four lesions showed osteolytic change. Most lesions on ¹⁸F-FDG PET/CT also demonstrated osteosclerotic change (17/20, 85.0 %) with three osteolytic lesions. All true metastatic lesions detected on WBBS and ¹⁸F-FDG PET/CT were identified on ¹⁸F-fluoride PET/CT.

Conclusion

¹⁸F-fluoride PET/CT is superior to WBBS or ¹⁸F-FDG PET/CT in detecting osteosclerotic metastatic lesions. ¹⁸F-fluoride PET/CT might be useful in evaluating osteosclerotic metastases in breast cancer patients.     

<Superscript>18</Superscript>F-FDG PET/CT in sarcoidosis management: review and report of 20 cases

PURPOSE: To evaluate the interest of (18)F-fluoro-2-deoxy-D: -glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for diagnosis and therapeutic follow-up of patients with sarcoidosis. METHODS: Twenty consecutive patients with biopsy-proven sarcoidosis were retrospectively included, in particular, 13 and seven cases of thoracic and extra-thoracic sarcoidosis, respectively. All patients underwent (18)F-FDG PET/CT, and 12 of them also (67)Ga scintigraphy. Five patients were re-examined by (18)F-FDG PET/CT to assess response to corticosteroid (CS) treatment. RESULTS: Sensitivity of (18)F-FDG PET/CT in detecting active sarcoidosis localizations was determined considering only biopsy-proven sites. For thoracic, sinonasal, and pharyngo-laryngeal localizations, (18)F-FDG PET/CT sensitivity was 100%, 100%, and 80%, respectively. Overall sensitivity for all 36 biopsy-proven localizations improved from 78% to 87% after excluding skin involvement. Considering only the 12 patients who underwent both scintigraphic examinations, overall sensitivity of (67)Ga scintigraphy and (18)F-FDG PET/CT was 58% and 79%, respectively and improved to 67% and 86% after excluding all sites of skin involvement. To evaluate the efficacy of CS treatment, five enrolled patients underwent second (18)F-FDG PET/CT. Complete regression of all foci of pathological tracer uptake was showed in two cases, permitting CS withdrawal after 2 and 6 months. Improvement but incomplete regression of mediastino-pulmonary disease occurred in two patients treated with CS for 19 and 21 months. Disease progression was assessed in one patient treated with decreasing doses of CS during 16 months. CONCLUSION: (18)F-FDG PET/CT allows to obtain a complete morpho-functional cartography of inflammatory active localizations and to follow treatment efficacy in patients with sarcoidosis, particularly in atypical, complex, and multisystemic forms.     

Comparison between <Superscript>68</Superscript>Ga-DOTA-NOC and <Superscript>18</Superscript>F-DOPA PET for the detection of gastro-entero-pancreatic and lung neuro-endocrine tumours

PURPOSE: (18)F-FDG positron emission tomography (PET) value for the assessment of neuro-endocrine tumours (NET) is limited. Preliminary studies indicate that (18)F-DOPA and (68)Ga-DOTA-NOC are more accurate for disease assessment and (68)Ga-DOTA peptides provide additional data on receptor status that are crucial for targeted radionuclide therapy. At present, there are no comparative studies investigating their role in NET. AIM: The aim of this study was to compare (68)Ga-DOTA-NOC and (18)F-DOPA for the evaluation of gastro-entero-pancreatic and lung neuro-endocrine tumours. MATERIALS AND METHODS: Thirteen patients with biopsy-proven NET (gastro-entero-pancreatic or pulmonary) were prospectively enrolled and scheduled for (18)F-DOPA and (68)Ga-DOTA-NOC PET. PET results obtained with both tracers were compared with each other, with other conventional diagnostic procedures (CT, ultrasound) and with follow-up (clinical, imaging). RESULTS: The most common primary tumour site was the pancreas (8/13) followed by the ileum (2/13), the lung (2/13) and the duodenum (1/13). The carcinoma was well differentiated in 10/13 and poorly differentiated in 3/13 cases. (68)Ga-DOTA-NOC PET was positive, showing at least one lesion, in 13/13 cases while (18)F-DOPA PET was positive in 9/13. On a lesions basis, (68)Ga-DOTA-NOC identified more lesions than (18)F-DOPA (71 vs 45), especially at liver, lung and lymph node level. (68)Ga-DOTA-NOC correctly identified the primary site in six of eight non-operated cases (in five cases, the primary was surgically removed before PET), while (18)F-DOPA identified the primary only in two of eight cases. CONCLUSIONS: Although the patients studied are few and heterogeneous, our data show that (68)Ga-DOTA-NOC is accurate for the detection of gastro-entero-pancreatic and lung neuro-endocrine tumours in either the primary or metastatic site and that it offers several advantages over (18)F-DOPA.     

Correlation between Semi-Quantitative <Superscript>18</Superscript>F-FDG PET/CT Parameters and Ki-67 Expression in Small Cell Lung Cancer

Purpose

The aim of this study was to evaluate the relationship between semiquantitative parameters on ¹⁸F-FDG PET/CT including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and the expression level of Ki-67 in small-cell lung cancer (SCLC).

Methods

Ninety-four consecutive patients with SCLC were enrolled in this study. They underwent ¹⁸F-FDG PET/CT for initial evaluation of SCLC, and we measured SUVmax, avgSUVmean, MTVsum, and TLGtotal on ¹⁸F-FDG PET/CT images. The protein expression of Ki-67 was examined by immunohistochemical staining.

Results

Significant correlations were found between the MTVsum and Ki-67 labeling index (r = 0.254, p = 0.014) and the TLGtotal and Ki-67 labeling index (r = 0.239, p = 0.020). No correlation was found between the SUVmax and Ki-67 labeling index (r = 0.116, p = 0.264) and the avgSUVmean and Ki-67 labeling index (r = 0.031, p = 0.770). Dividing the Ki-67 expression level into three categories, it was suggested that increasing Ki-67 expression level caused a stepwise increase in the MTVsum and TLGtotal. (p = 0.028 and 0.039, respectively), but not the SUVmax and avgSUVmean (p = 0.526 and 0.729, respectively).

Conclusion

In conclusion, the volume-based parameters of ¹⁸F-FDG PET/CT correlate with immunohistochemical staining of Ki-67 in SCLC. Measurement of the MTVsum and TLGtotal by ¹⁸F-FDG PET/CT might be a simple, noninvasive, and useful method to determine the proliferative potential of cancer cells.     

Distant metastases and synchronous second primary tumors in patients with newly diagnosed oropharyngeal and hypopharyngeal carcinomas: evaluation of <Superscript>18</Superscript>F-FDG PET and extended-field multi-detector row CT

Introduction  Patients with oropharyngeal or hypopharyngeal squamous cell carcinoma (SCC) have a high risk of having distant metastases or second primary tumors. We prospectively evaluate the clinical usefulness of ¹⁸F-fluoro-2-deoxyglucose positron emission tomography (¹⁸F-FDG PET), extended-field multi-detector computed tomography (MDCT), and their side-by-side visual correlation for the detection of distant malignancies in these two tumors at presentation. Materials and methods  A total of 160 patients with SCC of the oropharynx (n = 74) or hypopharynx (n = 86) underwent ¹⁸F-FDG PET and extended-field MDCT to detect distant metastases or second primary tumors. Suspected lesions were investigated by means of biopsy, clinical, or imaging follow-up. Results  Twenty-six (16.3%) of our 160 patients were found to have distant malignancy. Diagnostic yields of ¹⁸F-FDG PET and MDCT were 12.5% and 8.1%, respectively. The sensitivity of ¹⁸F-FDG PET for detection of distant malignancies was 1.5-fold higher than that of MDCT (76.9% vs. 50.0%, P = 0.039), while its specificity was slightly lower (94.0% vs. 97.8%, P = 0.125). Side-by-side visual correlation of MDCT and ¹⁸F-FDG PET improved the sensitivity and specificity up to 80.8% and 98.5%, respectively, leading to alteration of treatment in 13.1% of patients. A significant difference in survival rates between its positive and negative results was observed. Conclusion   ¹⁸F-FDG PET and extended-field MDCT had acceptable diagnostic yields for detection of distant malignancies in untreated oropharyngeal and hypopharyngeal SCC. ¹⁸F-FDG PET was 1.5-fold more sensitive than MDCT, but had more false-positive findings. Their visual correlation improved the diagnostic accuracy, treatment planning, and prognosis prediction.     

Evaluation of liver metastases after radiofrequency ablation: utility of 18F-FDG PET and PET/CT

OBJECTIVE: Our objective was to review the CT appearance of liver metastases after radiofrequency ablation and to describe the imaging findings of and utility of (18)F-FDG PET and PET/CT in assessing tumor recurrence after ablation. CONCLUSION: (18)F-FDG PET and PET/CT can provide added diagnostic information compared with conventional imaging in patients after radiofrequency ablation of liver metastases and can be useful in guiding repeat ablation procedures.     

Diagnosis of tumor in the nasal cavity and paranasal sinuses with [<Superscript>11</Superscript>C]choline PET: Comparative study with 2-[<Superscript>18</Superscript>F]fluoro-2-deoxy-<Emphasis Type="SmallCaps">d</Emphasis>-glucose (FDG) PET

[11C]choline (11C-choline) positron emission tomography (PET) was performed to evaluate its clinical utility in the diagnosis of tumors in the nasal cavity and paranasal sinuses. We studied 22 patients with suspicion of malignant tumors in the nasal cavity and paranasal sinuses. Tumor uptake of 11C-choline was measured with standardized uptake value (SUV) and correlated with the pathological diagnosis. 2-[18F]fluoro-2-deoxy-D-glucose (FDG) PET was performed in all patients for comparison. Both 11C-choline and FDG PET depicted squamous cell carcinoma showing an increased activity significantly higher than that of normal tissue, and these SUVs were significantly higher than those of benign lesions. FDG uptake in malignant tumors as a whole was variable. Although 11C-choline uptake in squamous cell carcinoma was lower than FDG uptake, 11C-choline uptake in malignant tumors was relatively uniform and statistical significance was found. PET with 11C-choline may be useful to diagnosis tumors in the nasal cavity and paranasal sinuses.     

<Superscript>18</Superscript>F-FDG PET/CT Imaging of Pulmonary Mucinous Cystadenocarcinoma with Signet Ring Cells

A 63-year-old male with a recently diagnosed right lung lesion was referred for staging. F-FDG PET/CT scan revealed a hypodense, cystic-like mass in the right upper lung lobe, which demonstrated low, diffuse ¹⁸F-FDG uptake, likely due to the presence of mucus, as well as intensely hypermetabolic right hilar and right paratracheal lymph nodes. Transbronchial biopsy revealed a primary pulmonary mucinous cystadenocarcinoma with the presence of signet ring cell carcinoma, a co-existence of two rare variants of lung adenocarcinoma. This case report demonstrates the metabolic phenotype along with the radiographic characteristics of this rare tumor and its metastases.     

Optimal dose of <Superscript>18</Superscript>F-FDG required for whole-body PET using an LSO PET camera

Reducing the acquisition time of whole-body fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) (corrected for attenuation) is of major importance in clinical practice. With the introduction of lutetium oxyorthosilicate (LSO), the acquisition time can be dramatically reduced, provided that patients are injected with larger amounts of tracer and/or the system is operated in 3D mode. The aim of this study was to determine the optimal dose of ¹⁸F-FDG required in order to achieve good-to-excellent image quality when a "3-min emission, 2-min transmission/bed position" protocol is used for an LSO PET camera. A total of 218 consecutive whole-body ¹⁸F-FDG PET studies were evaluated retrospectively. After excluding patients with liver metastases, hyperglycaemia and paravenous injections, the final study population consisted of 186 subjects (112 men, 74 women, age 59±15 years). Patients were injected with an activity of ¹⁸F-FDG ranging from 2.23 to 15.21 MBq/kg. Whole-body images corrected for attenuation (3 min emission, 2 min transmission/bed position) were acquired with an LSO PET camera (Ecat Accel,Siemens) 60 min after tracer administration. Patients were positioned with their arms along the body. Image reconstruction was done iteratively and a post-reconstruction filter was applied. Image quality was scored visually by two independent observers using a five-point scoring scale (poor, reasonable, good, very good, excellent). In addition, the coefficient of variability (COV) was measured in a region of interest over the liver in order to quantify noise. Of the images obtained in 118 patients injected with 8 MBq/kg ¹⁸F-FDG, 92% and 90% were classified as good, very good or excellent by observer 1 and observer 2, respectively. The COV averaged 10.63%±3.19% for doses 8 MBq/kg and 16.46%±5.14% for doses <8 MBq/kg. Administration of an ¹⁸F-FDG dose of 8 MBq/kg results in images of good to excellent quality in the vast majority of patients when using an LSO PET camera and applying a 3-min emission, 2-min transmission/bed position acquisition protocol. At lower doses, a rapid decline in image quality and increasing noise are observed. Alternative protocols should be adopted in order to compensate for the loss in image quality when doses <8 MBq/kg are used.     

Usefulness of <Superscript>18</Superscript>F-fluorodeoxyglucose positron emission tomography for diagnosing disease activity and monitoring therapeutic response in patients with pulmonary mycobacteriosis

Purpose  To evaluate the usefulness of ¹⁸F-FDG PET in the imaging of pulmonary lesions related to disease activity and in monitoring responses to treatment in patients with pulmonary mycobacteriosis (PM). Materials and methods  We used high-resolution computed tomography (HRCT) and ¹⁸F-FDG PET to evaluate 47 consecutive untreated patients with PM, 25 with tuberculosis (TB) and 22 with Mycobacterium avium-intracellulare complex (MAC), who presented with small peripheral pulmonary nodules ≤3 cm, and compared the findings. The diagnosis of mycobacteriosis was confirmed by bacteriological examinations of bronchoscopic or surgically resected specimens. PET scans were visually and quantitatively analysed using SUVmax. In addition, 14 patients with PM underwent repeat PET scanning during antimycobacterial therapy, and changes in ¹⁸F-FDG uptake were clinically evaluated (6 during treatment and 12 after treatment). Results  Of all the lesions, 87.2% had SUVmax levels ranging from 3 to 7 (5.05 ± 1.56, range 2.5–7.6, n = 47). Further, SUV levels in patients with PM reflected disease activity as estimated by HRCT, but did not differ significantly between those with TB (4.96 ± 1.61, n = 25) and MAC (5.15 ± 1.53, n = 22). ¹⁸F-FDG uptake was significantly decreased in all 14 patients who received chemotherapy, indicating a positive response to treatment. Conclusion   ¹⁸F-FDG PET is considered to be useful for the diagnosis and evaluation of disease activity along with HRCT findings, and in monitoring response to chemotherapy in patients with PM.