Kerim Sonmezoglu

The additional value of FDG PET imaging for distinguishing N0 or N1 from N2 stage in preoperative staging of non-small cell lung cancer in region where the prevalence of inflammatory lung disease is high.

Purpose: The aim of this study was to evaluate the efficacy of PET imaging and compare it with the performance of CT in mediastinal and hilar lymph node staging in potentially operable non-small cell lung cancer (NSCLC). Methods: Fifty-nine patients with potentially resectable NSCLC who underwent preoperative PET and CT imaging were enrolled into this prospective study. All patients underwent surgical evaluation by means of mediastinoscopy with mediastinal lymph node sampling (14 patients) or thoracotomy (45 patients). Results: The prevalence of lymph node metastases was 53%. Overall, the sensitivity, specificity, accuracy, PPV, and NPV of PET were 79%, 76%, 78%, 86%, and 76% for N0 and N1 lymph nodes and 76%, 79%, 80%, 67%, and 83% for N2 lymph nodes, while those values for CT were 66%, 43%, 58%, 68%, and 43% for N0 and N1 stations and 43%, 66%, 54%, 41%, and 66% for N2 lymph nodes, respectively. PET correctly differentiated cases with mediastinal lymph node involvement (N2) from those without such involvement (N0 or N1) in 76% of cases. Statistical analysis of the diagnostic accuracy of nodal involvement showed that PET improves diagnostic accuracy significantly in the detection of both N0 or N1 and N2 status in the individual patient based on analysis, compared with CT (P < 0.01 and P < 0.01, respectively). When preoperative nodal staging was compared with postoperative histopathological staging, 38 (65%) patients were correctly staged, 9 (15%) were overstaged, and 12 (20%) were understaged by PET, while 29 patients (49%) were correctly staged, 13 (22%) were overstaged, and 17 (29%) were understaged by CT. Conclusion: It has been clearly shown that PET is more accurate than CT for the differentiation of N0 or N1 from N2 disease in patients with NSCLC. However, PET imaging alone does not appear to be sufficient to replace mediastinoscopy for mediastinal staging in patients with lung cancer, especially in geographic regions with high granulomatous or inflammatory mediastinal disease prevalence.

Correlation of technetium-99m MIBI and thallium-201 retention in solitary cold thyroid nodules with postoperative histopathology

Abstract.A comparative prospective study of technetium-99m methoxyisobutylisonitrile (MIBI) and thallium-201 with early (15 min) and delayed (90 min for MIBI, 3 h for 201Tl) imaging in the differentiation of thyroid lesions is presented. Forty patients with cold thyroid nodules visualised on 99mTc-pertechnetate scan and with dyskaryotic or atypical epithelial cells verified by fine-needle aspiration biopsy underwent MIBI and 201Tl scintigraphy at 3-day intervals. Subsequent thyroidectomies were carried out in all patients. Semiquantitative analysis was performed using a lesion to non-lesion ratio on early (ER) and delayed images (DR). Additionally, a retention index (RI) was calculated using the formula RI=(DR– ER) × 100/ER. The reproducibility of the method for the early and delayed measurements was tested by analysing intra- and inter-observer variability and repeatability coefficients. Histopathologically, the nodules were found to be well-differentiated thyroid cancer in 21 patients and benign in 19 patients. There was no significant difference in the ER between malignant and benign lesions for either 201Tl or MIBI (P>0.05). However, for both agents significant differences were found between malignant and benign lesions with regard to DR (P<0.01 for 201Tl and P<0.001 for MIBI) and RI (P<0.001 for both agents). Statistical comparison of the two agents showed no significant differences (P>0.05) except with regard to DR and RI in malignant nodules (P<0.05). A receiver operating characteristic analysis was performed to determine threshold levels for the differentiation of malignant from benign nodules. Following this analysis, ER, DR and RI levels of 1.03, 1.54 and 2 for MIBI and ≤1.42, 1.24 and 5 for 201Tl were selected. Using these threshold levels, the sensitivity, specificity and accuracy of the study were 90.5%, 36.8% and 65% for ER MIBI, 61.9%, 94.7% and 77.5% for DR MIBI, 95.2%, 89.4% and 92.5% for RI MIBI, 85.7%, 47.3% and 67.5% for ER 201Tl, 80.9%, 73.6% and 77.5% for DR 201Tl, and 90.5%, 94.7% and 92.5% for RI 201Tl. In conclusion, the DR for MIBI and 201Tl is superior to the ER in detecting malignant nodules, and the RI for both MIBI and 201Tl is more valuable than the DR in differentiating malignant from benign thyroid nodules.

Correlation of 18F-fluorodeoxyglucose uptake with histopathological prognostic factors in breast carcinoma.

ObjectiveThis study investigated the prognostic value of [18F]-fluorodeoxyglucose (18F-FDG) uptake in breast carcinomas by comparing 18F-FDG PET/computed tomography (CT) images with histopathological and immunohistochemical prognostic factors. MethodsThis study included 136 women and four men with positive biopsy breast carcinomas who underwent 18F-FDG PET/CT imaging for initial staging. Maximum standardized uptake values (SUVmax) and tumour-to-background SUVmax ratios were calculated and compared with histopathological and immunohistochemical tumour characteristics, patient properties and axillary lymph node involvement. Calculations of SUVmax for men were performed separately. ResultsFor the tumours in women, the mean SUVmax was 10.06±6.91 and the median SUVmax was 9.05 (0.7–35.0). Primary tumour 18F-FDG uptake and tumour-to-background SUVmax ratios were correlated with tumour size (P<0.001), histological type (P<0.001), histological grade (P=0.004), pleomorphism (P=0.010), mitosis count (P<0.001), lymphatic invasion (P=0.009), necrosis (P=0.005), oestrogen negativity (P=0.004), high Ki-67 level (P<0.001), axillary lymph node involvement (P<0.001) and triple negativity (P=0.002). High Ki-67 level (odds ratio=16; 95% confidence interval=1.6–160; P=0.016) and tumour size (odds ratio=4; 95% confidence interval=1.5–11; P=0.007) were determining factors for high 18F-FDG uptake values. Other clinicopathological and immunohistopathological parameters including progesterone receptor (P=0.211), CerbB2 overexpression (P=0.170), perineural invasion (P=0.053), intratumoural calcification (P=0.438), desmoplasia (P=0.112), tubular formation (P=0.768) and age (P=0.675) were not significantly correlated with 18F-FDG uptake. No significant relationship was observed between the tumour/contralateral breast SUVmax ratio and mitotic count, oestrogen receptor status or triple negativity. Conclusion18F-FDG uptake may serve as a prognostic indicator for biological behaviour in breast tumours.

A doughnut sign of a hydatid cyst of the liver on F-18 FDG PET/CT.

A 59-year-old man underwent a whole-body PET/CT scan to evaluate the metabolic activity of a nodule in the upper lobe of the left lung seen on CT. Slightly increased peripheral activity with a large hypometabolic region centrally, a so-called doughnut sign, was seen in the right lobe of the liver. After the diagnosis of a hydatid cyst of the liver, the patient underwent surgery. This case demonstrates a hydatid cyst that caused increased F-18 FDG uptake as a doughnut pattern.

Avoidance of misinterpretation of an FDG positive sacral insufficiency fracture using PET/CT scans in a patient with endometrial cancer: a case report.

Whole-body FDG PET is an important tool for imaging of cancer, including skeletal metastases. However, false-positive results can occur in benign diseases such as insufficiency fractures. We report a case of sacral insufficiency fracture in which increased FDG uptake was detected. Correlative CT images obtained by a combined PET/CT scanner excluded a possible false-positive interpretation by revealing the fracture lines at the site of increased FDG uptake.

Incidental Detection of Follicular Thyroid Carcinoma in 68Ga-PSMA PET/CT Imaging

Prostate-specific membrane antigen (PSMA) is a type II transmembrane protein. It has been shown to be expressed in various solid malignant neoplasms. We report a case of a prostate cancer patient who underwent 68Ga-PSMA PET/CT imaging. There is a large thyroid nodule in the right thyroid gland, which had intense PSMA accumulation. Follicular thyroid lesions can be seen on 68Ga-PSMA PET/CT imaging.

Positron emission tomography findings in children with infantile spasms and autism

The purpose of this study was to evaluate positron emission tomography (PET) findings in patients diagnosed with infantile spasms and autism. This study includes 90 patients who were diagnosed with infantile spasms at the Department of Pediatric Neurology in the Istanbul University Medical Faculty between 1995 and 2007. Of the 90 patients, 15 patients who were diagnosed with autism using the Autism Behaviour Checklist and Childhood Autism Rating Scale and a control group of nine patients without autism but with infantile spasms underwent PET examination. Mean patient age (± standard error, SE) varied between 3 years and 16 years (7.8 ± 4 years), while the mean follow-up time (±SE) varied between 2 years and 16 years (average: 7.1 ± 4 years). Autism was present in 11 patients with symptomatic spasms and in four patients with cryptogenic spasms (p=0.009). On the PET scans of the 15 patients with autism, 13 (86.7%) had significantly decreased metabolic activity in the temporal lobe (p<0.001), nine (60%) had significantly decreased activity in the frontal lobe (p=0.004), and seven (46.7%) had significantly decreased activity in the parietal lobe (p=0.022). In our opinion, hypometabolism in the frontal and parietal lobes, in addition to that previously reported in the temporal lobe, plays a role in the development of autism in patients with infantile spasms.

The role of 99Tcm-tetrofosmin in the evaluation of thyroid nodules

Various radionuclides, including 67Ga, 201Tl and 99Tcm-sestamibi, have been used to differentiate benign from malignant thyroid nodules. 99Tcm-tetrofosmin, a lipophilic cationic radiotracer, and 99Tcm-sestamibi have also been reported to accumulate in thyroid tumours. In this study, we evaluated the role of 99Tcm-tetrofosmin in the differentiation of malignant from benign thyroid nodules. Seventy-nine patients with solitary non-functioning thyroid nodules were included in the study. Fine-needle aspiration biopsy was performed in all patients. Sixty patients were subsequently operated on and 19 patients refused surgery. After the injection of 370 MBq 99Tcm-tetrofosmin, static images at 5, 30, 60, 120 and 180 min were acquired. Both visual and semi-quantitative analysis was performed. On visual interpretation, the nodules with late retention were classified as positive for malignancy and nodules without late retention were classified as negative for malignancy. In the semi-quantitative analysis, regions of interests were drawn over the nodule and contralateral normal thyroid tissue. The average number of counts was recorded and tumour-to-normal thyroid tissue ratios calculated. Post-operative histology revealed 19 malignant and 41 benign nodules. Of the benign nodules, adenomas behaved similarly to the malignant nodules with late retention of tracer, while adenomatous nodules revealed no late retention on delayed images and could be differentiated from malignant tumours. In the semi-quantitative analysis, there was a significant difference in tumour-to-normal tissue ratios for adenomatous nodules and malignant tumours as well as adenomas. We conclude that it is not possible to differentiate between malignant and benign thyroid nodules with 99Tcm-tetrofosmin. However, 99Tcm-tetrofosmin scintigraphy is helpful in selecting nodules that can be cured by surgical intervention.

FDG PET/CT findings in primary hyperparathyroidism mimicking multiple bone metastases

We present a 40-year-old female patient with a history of generalized bone pain and fatigue for 6 months. Hyperparathyroidism (PTH 1,629 pg/ml, normal range 12–65), parathyroid adenomas, hypophysis adenoma, clinical symptoms for insulinoma, and left adrenal mass were shown in her routine biochemical analysis, radiological, and scintigraphy images. MEN type I was suspected according to these findings. FDG PET/CTwas planned to exclude a malignancy. In fasting state, the patient was injected 370 MBq of FFDG intravenously. After the 1-h waiting period, a whole body FDG PET/CT image of the patient was obtained using an integrated PET/CT camera (Siemens Biograph LSO HIREZ PET/CT scanner, Chicago, IL, USA). The maximum intensity projection image of the FDG PET/CT demonstrated diffusely and multiple foci of increased FDG uptake throughout the skeleton, mimicking multiple bone metastases (a). However, there was no pathological uptake suggesting malignancy. After FDG PET/CT, a whole body bone scan (b) was obtained and showed a diffusely increased uptake in whole skeleton (especially in the calvarium, pelvis, and lower extremities) in a pattern highly suggestive of a hypermetabolic bone disease rather than bone metastases. The patient was than operated on for parathyroid pathology. PTH returned to the normal levels on follow-up of the patients. In patients with hyperparathyroidism, findings in bone scan and FDG PET/CT should be analyzed and reported very carefully [1–5]. References

Diagnostic value of F-18 FDG PET/CT in patients with spondylodiscitis: Is dual time point imaging time worthy?

PURPOSE In this retrospective study, we aimed to investigate the value of FDG-PET/CT in the diagnosis of spondylodiscitis (SD), the significance of dual time point imaging (DTPI) for SD diagnosis and the worth of SUVmax data for distinguishing tuberculous vs. non-tuberculous SD. MATERIALS AND METHODS 32 patients with suspected SD were scanned with FDG-PET/CT. For quantitative analysis maximum standardized uptake value (SUVmax) of the lesion area was measured. Nineteen patients had DTPI of FDG-PET/CT. The final diagnoses were achieved by histopathological, microbiological, and clinical results. RESULTS Specific pathogens were isolated in 21 patients; other patients were accepted as nonspecific bacterial SD. In all patients, FDG-PET/CT results were compatible with SD diagnosis. The SUVmax data for tuberculous and non-tuberculous SD and DTPI results were statistically insignificant. CONCLUSION FDG-PET/CT is a successful modality for SD diagnosis; additionally, DTPI protocol for FDG-PET/CT in SD diagnosis and SUVmax data for differentiation between non-tbc SD and tbc SD are useless.