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.

Comparison of F-18 FDG-PET/CT and Tc-99m MIBI in the preoperative evaluation of cold thyroid nodules in the same patient group.

Recent studies have reported that standardized uptake values of FDG-PET imaging might predict malignant thyroid nodules and can be used in the preoperative evaluation of thyroid lesions. The aim of our study was to evaluate FDG-PET imaging in patients with cold thyroid nodules and to compare the imaging findings with Tc-99m MIBI scans and with post-op histopathology results. Twenty-three patients (18F, 5M) with 24 nodules that were suspicious in ultrasound and cold in Tc-99m pertechnetate scan, were included in the study. Each nodule underwent sonographically guided fine-needle aspiration biopsy. FDG-PET and MIBI scans were performed with an interval of 3-5 days. All patients underwent thyroidectomy and their FDG-PET, and MIBI thyroid scan results were compared with post-thyroidectomy pathology results. Post-op histopathology results found 7 malignant and 17 benign nodules. Six of the seven malignant nodules had increased uptake, which were positive for malignancy in both PET and MIBI scans. Each imaging method used different radiopharmaceuticals but showed one false-negative result in two different patients. FDG-PET produced false positives in eight nodules and MIBI scans found false positives in four nodules. FDG-PET imaging and MIBI scan showed the same sensitivity in malignant nodule evaluation, but their specificity differed. As a result, we suggest that FDG-PET imaging is not superior to MIBI scanning in differentiating malignant from benign thyroid nodules. MIBI imaging should be the first choice in the preoperative evaluation of patients with cold thyroid nodules as an adjunct procedure to FNAB because of its low cost and availability. This imaging technique can be used routinely in patients who are reluctant to undergo FNAB.

Utility of left lateral supine position for myocardial perfusion single-photon emission computed tomography compared with other methods of correcting inferior wall attenuation.

INTRODUCTION: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging is an accepted method for reflecting the pathophysiological significance of lesions detected by coronary angiography. However, it has an inherent drawback in terms of false-positive perfusion defects for the inferior myocardial wall. To overcome this problem, different acquisition techniques have been proposed, including the computed tomographic-based attenuation correction method. In this respect, a new imaging technique, left supine lateral position SPECT myocardial perfusion imaging with technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI), has been proposed to eliminate this problem and its value has been investigated in this report. MATERIALS AND METHODS: Sixty-two patients were prospectively and randomly enrolled in this study. They underwent Tc-99m MIBI SPECT in the supine, prone, left lateral, and sitting positions after an adequate stress test on the same day.The presence and extent of defects on stress images were noted in the supine image data set for the 11 myocardial segments, which were then labeled as 1 or 0 if a defect was present or absent, respectively. This evaluation sequence was repeated in all other image data sets. When defects persisted in other scan positions it was regarded as true positive, and when they were resolved they were regarded as false positive. By this means, the percentages of resolving perfusion defects by that imaging position were calculated for each observer per positional pair under comparison. RESULTS: From six interpretations carried out by the nuclear medicine physicians, 6×11×3=198 four-fold tables in 11 segments were analyzed for discrepancies between position pairs. In 31 of 33 discrepant interpretations, defects observed in any of the other positions were resolved in the lateral position. Only in two evaluations of one observer were the discrepancies against lateral positioning for the anterior wall. If the inferior wall was considered alone, it was clearly obvious that lateral positioning was more accurate than the other positions.Intraobserver evaluation showed the methodology to be highly reproducible.The SPECT findings were concordant with coronary angiography results in selected patients. CONCLUSION: Visual and quantitative evaluations of the variation in inferior wall activity lead us to suggest that SPECT imaging with Tc-99m MIBI be performed in the left lateral position to allow better visualization of the inferior and septal walls in those departments not able to utilize computed tomographic attenuation correction.

Regional ventilation/perfusion mismatch pattern in patient with Swyer James (MacLeod's) syndrome.

Swyer James (McLeod's) syndrome (SJMS) is an uncommon disease, which occurs as a result of childhood bronchiolitis obliterans. Patients may not be diagnosed until later in their life. A 46-year-old man underwent ventilation/perfusion scintigraphy for acute onset of dyspnea. The scan showed markedly diminished ventilation and perfusion unilaterally on the right middle and inferior lobes. However, mismatched ventilation-perfusion pattern was shown on the upper right lobe, which was consistent with pulmonary embolism. Unilaterally matched ventilation/perfusion defect can see in SJMS in lung scintigraphy; however, when pulmoner embolism may accompany, scintigraphy should be carefully examined.

A rare case of solitary subcutaneous scalp metastasis from follicular thyroid carcinoma revealed with positron emission tomography/computed tomography: a case report and review.

Differentiated thyroid cancer frequently metastasizes to regional cervical lymph nodes and in advanced cases metastases can be seen in the lungs and skeleton. Metastases to the skin or subcutaneous tissue are rare. Here we present a 49-year-old female patient with solitary scalp metastasis from follicular thyroid carcinoma FTC which was revealed with positron emission tomography (PET)/computed tomography (CT) imaging. PET showed flourodeoxiglucose avid lesion in the left vertex scalp. Scalp lesion was removed totally and histopathological examination revealed well-differentiated thyroid cancer metastasis.

FDG and FDG-labelled leucocyte PET/CT in the imaging of prosthetic joint infection.

PURPOSE: The demand for arthroplasty is rapidly growing as a result of the ageing of the population. Although complications such as heterotrophic ossification, fracture and dislocation are relatively rare, differentiating aseptic loosening, the most common complication of arthroplasty from infection, is a major challenge for clinicians. Radionuclide imaging is currently the imaging modality of choice since it is not affected by orthopaedic hardware. Whereas FDG PET/CT imaging has been widely used in periprosthetic infection, it cannot discriminate aseptic from septic inflammation. In this study we aimed to evaluate the role of FDG PET/CT and FDG-labelled leucocyte PET/CT in the diagnosis of periprosthetic infection. METHODS: Of 54 patients with painful joint arthroplasty who were imaged by FDG PET/CT for diagnosis of periprosthetic infection examined, 46 (36 women, 10 men; mean age 61.04 ± 12.2 years, range 32-89 years) with 54 painful joint prostheses (19 hip, 35 knee) with grade 2 (above liver uptake) FDG accumulation on FDG PET/CT were included in the study and these 46 patients also underwent FDG-labelled leucocyte PET/CT. Final diagnoses were made by histopathological-microbiological culture or clinical follow-up. RESULTS: The final diagnosis showed infection in 15 (28%) and aseptic loosening in 39 (72%) of the 54 prostheses. FDG PET/CT was found to have a positive predictive value of 28% (15/54). Since patients with no FDG uptake on FDG PET/CT were excluded from the study, the sensitivity, specificity, negative predictive value and accuracy could not be calculated. The sensitivity, specificity, and positive and negative predictive values of FDG-labelled leucocyte PET/CT were 93.3% (14/15), 97.4% (38/39), 93.3% and 97.4%, respectively. CONCLUSION: Since FDG is not specific to infection, the specificity of FDG PET/CT was very low. FDG-labelled leucocyte PET/CT with its high specificity may be a useful method and better than labelled leucocyte scintigraphy in periprosthetic infection imaging.

Prognostic significance and predictive performance of volume-based parameters of F-18 FDG PET/CT in squamous cell head and neck cancers.

AIM: It has been previously reported that metabolic tumor volume on positron emission tomography-computed tomography predicts disease recurrence and death in head-and-neck cancer. In this study, we assessed the prognostic value of metabolic tumor volume measured using F18-Fluorodeoxyglucose PET/CT in patients with head and neck squamous cell carcinoma. MATERIALS AND METHODS: We analyzed the imaging findings of 74 patients (age 57±16) retrospectively, with head and neck cancer who underwent PET/CT scan for staging and after treatment. Forty-tree patients had nasopharynx, 15 patients had hypopharynx, 9 patients had larynx, and 7 patients had oropharynx cancer. The MTVs of primary sites with or without lymph nodes were measured, and outcomes were assessed using the treatment response evaluation by the Response Evaluation Criteria in Solid Tumors and recurrence events during follow-up. RESULTS: A total of 48 patients had complete response or no recurrence was detected as of in the last follow-up. Of the first PET/CT scan, the median primary tumor SUVmax was 18.8 and the median nodal SUVmax was 13.4. The median primary tumor MTV% 50s ranged from 11.12 cm3 to 16.28 cm3, and the MTV after the therapy ranged from 1.18 cm3 to 3.51 cm3. CONCLUSION: Metabolic tumor volume (MTV) represents tumor burden, which shows F18-Fluorodeoxyglucose uptake and has a potential value in predicting short-term outcome and disease-free survival in patients with head and neck cancer.

Clinical value of technetium-99m-labeled octreotide scintigraphy in local recurrent or metastatic medullary thyroid cancers: a comparison of lesions with 18F-FDG-PET and MIBI images.

AIM: Various studies have been conducted for determining the most optimal method for the early diagnosis of local recurrent or distant metastatic thyroid cancers. The aim of this study was to evaluate the clinical utility of technetium-99m (Tc-99m)-labeled octreotide derivatives in the detection of recurrence or distant metastases in medullary thyroid cancer patients and to compare the lesions with those detected using 18F-fluorodeoxyglucose (18F-FDG)-PET and Tc-99m MIBI studies in the same patient group. PATIENTS AND METHODS: Sixteen medullary thyroid cancer patients [two male and 14 female; mean age 52.0 ± 14.1 years (range 13-72 years)] were included in this study. All patients underwent a whole-body scan 1 and 4 h after injection with octreotide derivatives and single photon emission computed tomography images were taken of the sites suspicious for metastasis. The lesions seen in Tc-99m HYNIC octreotide studies were compared with those seen in 18F-FDG-PET and Tc-99m MIBI studies. RESULTS: Among the Tc-99m-labeled octreotide scintigraphy studies, nine were evaluated as true positive (56.2%) and one was evaluated as false positive (6.2%); six were false negative (37.5%). In 16 patients, the total number of lesions seen on octreotide scintigraphy was 21. Thirteen of the 16 patients underwent 18F-FDG-PET imaging. Of the 13 patients studied, 10 showed true-positive (76.9%) and three showed false-negative (23.1%) results. The total number of lesions seen on 18F-FDG-PET was 23. The Tc-99m MIBI study yielded positive results in seven of 16 patients (43.7%) and negative results in nine patients (56.3%). The total number of lesions on Tc-99m MIBI was 12. CONCLUSION: The Tc-99m-labeled somatostatin receptor scintigraphy analogs HYNIC-tyrosine octreotide and HYNIC-TATE are useful imaging alternatives in somatostatin receptor-expressing thyroid cancers. Radiolabeling using these analogs is easy and they are readily available for routine use.

Evaluation and comparison of Ga-68 DOTA-TATE and Ga-68 DOTA-NOC PET/CT imaging in well-differentiated thyroid cancer.

BACKGROUND: Somatostatin receptor (Sstr) scintigraphy with radiolabelled somatostatin analogues has been used extensively for the diagnosis and therapy of Sstr-expressing tumours. It has been shown that well-differentiated thyroid cancer (WDTC) cells have a high expression of Sstr2, Sstr3 and Sstr5. Hence, WDTC cells could be an ideal target for the evaluation of lesion uptake of Ga-68 DOTA-1-NaI3-octreotide (DOTA-NOC), which has a high affinity not only to Sstr2 but also to Sstr3 and Sstr5. The aim of the present study was to evaluate the value of Ga-68 DOTA-NOC as a target for Sstr2-expressing, Sstr3-expressing and Sstr5-expressing tumours in WDTC patients and to compare the results with those of Ga-68 DOTA-TATE in the same patient population. METHOD: Thirteen patients with WDTC were included in our study: nine with papillary thyroid cancer, three with Hurthle cell carcinoma and one with follicular thyroid carcinoma. All patients had elevated serum thyroglobulin levels and negative post-therapeutic I-131 whole-body scans, which were obtained after the last radioiodine treatment. All patients had undergone two consecutive PET imaging studies with Ga-68 DOTA-D-Phe1-Tyr3-octreotate (DOTA-TATE) and Ga-68 DOTA-NOC, respectively. All images were evaluated visually, and maximum standardized uptake values were calculated. RESULTS: Both Ga-68 DOTA-TATE and Ga-68 DOTA-NOC PET images gave comparable results. Among the 13 patients, imaging with both Ga-68 DOTA-TATE and Ga-68 DOTA-NOC gave negative results in five (38%) patients and positive results in eight (62%) patients. A total of 45 lesions were identified on Ga-68 DOTA-TATE images and 42 on Ga-68 DOTA-NOC images; three lesions were missed. Lesion uptake was significantly higher on Ga-68 DOTA-TATE images. Maximum standardized uptake values of Ga-68 DOTA-TATE and Ga-68 DOTA-NOC were 12.9±9.1 and 6.3±4.1 (n=54, P<0.001), respectively. CONCLUSION: Our study suggested that Ga-68 DOTA-TATE has a higher lesion uptake even in WDTC patients and may have potential advantage over Ga-68 DOTA-NOC.

Comparison of Ga-68 DOTA-TATE and Ga-68 DOTA-LAN PET/CT imaging in the same patient group with neuroendocrine tumours: preliminary results.

INTRODUCTION: Recent studies have suggested that PET imaging with Ga-68-labelled DOTA-somatostatin analogues such as octreotide and octreotate is useful in diagnosing neuroendocrine tumours (NETs) and has superior value over both computed tomography and planar and SPECT somatostatin receptor scintigraphy. PURPOSE: The aim of the present study was to evaluate the role of Ga-68 DOTA-lanreotide (Ga-68-DOTA-LAN) in patients with somatostatin receptor (sst)-expressing tumours and to compare the results of Ga-68 DOTA-D-Phe1-Tyr3-octreotate (Ga-68-DOTA-TATE) in the same patient population. MATERIALS AND METHODS: Twelve patients with NETs who were referred to our department for somatostatin receptor scintigraphy were included in the study. There were four patients with well-differentiated neuroendocrine tumour (WDNET) grade 1, two patients with WDNET grade 2, and three patients with poorly differentiated neuroendocrine carcinoma (PDNEC) grade 3. There was also one patient with medullary thyroid cancer, one patient with meningioma and one patient with MEN-1. All patients underwent two consecutive PET imaging studies with Ga-68-DOTA-TATE and Ga-68 DOTA-LAN. All images were evaluated visually, and maximum standardized uptake value was calculated for quantitative evaluation. RESULTS: On visual examination of maximum intensity projection images, GA-68 DOTA-LAN was seen to have high background activity and high bone marrow uptake. Both tracers defined 67 lesions. Ga-68 DOTA-TATE images revealed 63 (94%) clearly defined lesions, missing four lesions. In contrast, Ga-68 DOTA-LAN images defined only 23 (44%) lesions, missing 44 (56%) lesions. Thirty-two bone lesions were detected on Ga-68-DOTA-TATE images. Among them, only 11 (34%) were positive on Ga-68 DOTA-LAN images, whereas 21 (66%) were negative. When we evaluated liver, mediastinum and gastrointestinal tract lesions, Ga-68 DOTA-LAN was seen to be positive for 12 (34%) lesions and negative for 23 (66%) lesions. CONCLUSION: Although the results are preliminary, the image quality obtained by Ga-68-DOTA-TATE seems to be superior to that obtained by Ga-68 DOTA-LAN. With its significantly higher lesion uptake and higher ability to detect lesions, Ga-68-DOTA-TATE seems to be a better radioligand compared with Ga-68-DOTA-LAN for the diagnosis of NETs.

Comparison of 99mTc-HYNIC-TOC and HYNIC-TATE octreotide scintigraphy with FDG PET and 99mTc-MIBI in local recurrent or distant metastatic thyroid cancers.

AIM: There have been various studies for early diagnosis of local recurrent or distant metastatic thyroid cancers. The aim of this study is to evaluate the clinical utility of 99mTc-HYNIC-TOC and 99mTc-HYNIC-TATE, octreotide derivatives, to detect recurrences or distant metastases in 131I-negative thyroglobulin positive thyroid cancer patients and to compare the lesions with FDG PET and 99mTc-MIBI studies in the same patient group. PATIENTS AND METHODS: Twenty differentiated thyroid cancer patients, 7 male and 13 female, mean age 54.6 ± 15.3 (range 13-78 years), were included in this study. Eighteen patients had papillary thyroid cancer and 2 had follicular thyroid cancer. Fifteen patients received HYNIC-TOC and 5 patients received HYNIC-TATE as a radiopharmaceutical. All patients underwent whole-body scan 1 and 4 hours after injection of octreotide derivatives and SPECT imagings were performed from the suspicious sites. The lesions that were seen in 99mTc-HYNIC-TOC and 99mTc-HYNIC-TATE studies were compared with 99mTc-MIBI and FDG-PET studies. RESULTS: Among 99mTc-HYNIC-TOC and 99mTc-HYNIC-TATE scintigraphies, 15 patient studies were evaluated as true positive (75%) and 5 were false negative (25%). The total number of lesions in octreotide scintigraphy was 48 in 20 patients. Of 20 patients, 19 had FDG-PET study, 15 of them were evaluated as true positive (78.9%), and 4 them were evaluated as false negative (21.1%). Total number of lesions in FDG PET was 74. 99mTc-MIBI study was positive in 11 patients (55%) and negative in 9 patients (45%). Total number of lesions in 99mTc-MIBI was 25. CONCLUSION: Technetium-labeled somatostatin receptor scintigraphy analogues HYNIC-TOC and HYNIC-TATE are useful imaging alternatives in somatostatin receptor expressing thyroid cancer patients. Radiolabeling is easy and they are readily available for routine use.

Comparison of 68Ga-DOTATATE and 68Ga-DOTANOC PET/CT imaging in the same patient group with neuroendocrine tumours.

PURPOSE: Recent studies have suggested that positron emission tomography (PET) imaging with (68)Ga-labelled DOTA-somatostatin analogues (SST) like octreotide and octreotate is useful in diagnosing neuroendocrine tumours (NETs) and has superior value over both CT and planar and single photon emission computed tomography (SPECT) somatostatin receptor scintigraphy (SRS). The aim of the present study was to evaluate the role of (68)Ga-DOTA-1-NaI(3)-octreotide ((68)Ga-DOTANOC) in patients with SST receptor-expressing tumours and to compare the results of (68)Ga-DOTA-D-Phe(1)-Tyr(3)-octreotate ((68)Ga-DOTATATE) in the same patient population. METHODS: Twenty SRS were included in the study. Patients' age (n = 20) ranged from 25 to 75 years (mean 55.4 ± 12.7 years). There were eight patients with well-differentiated neuroendocrine tumour (WDNET) grade1, eight patients with WDNET grade 2, one patient with poorly differentiated neuroendocrine carcinoma (PDNEC) grade 3 and one patient with mixed adenoneuroendocrine tumour (MANEC). All patients had two consecutive PET studies with (68)Ga-DOTATATE and (68)Ga-DOTANOC. All images were evaluated visually and maximum standardized uptake values (SUV(max)) were also calculated for quantitative evaluation. RESULTS: On visual evaluation both tracers produced equally excellent image quality and similar body distribution. The physiological uptake sites of pituitary and salivary glands showed higher uptake in (68)Ga-DOTATATE images. Liver and spleen uptake values were evaluated as equal. Both (68)Ga-DOTATATE and (68)Ga-DOTANOC were negative in 6 (30 %) patients and positive in 14 (70 %) patients. In (68)Ga-DOTANOC images only 116 of 130 (89 %) lesions could be defined and 14 lesions were missed because of lack of any uptake. SUV(max) values of lesions were significantly higher on (68)Ga-DOTATATE images. CONCLUSION: Our study demonstrated that the images obtained by (68)Ga-DOTATATE and (68)Ga-DOTANOC have comparable diagnostic accuracy. However, (68)Ga-DOTATATE seems to have a higher lesion uptake and may have a potential advantage.

Significance of increased scrotal Tc-99m MDP uptake in patients with prostate cancer.

OBJECTIVE: We observed an unusually increased scrotal uptake as an interesting finding in some patients with prostate cancer who were scanned for any possible metastatic disease. This study was designed to investigate the significance of this incidental finding in the technetium-99m methylene diphosphonate scintigraphies. METHODS: The study population consisted of 104 patients with biopsy-proven prostate cancer (group I), 55 male patients with other cancers (group II), 30 male patients with nonmalignant diseases (group III) and finally 15 patients with benign prostate hypertrophy (group IV). The square-shaped regions of interest are placed centrally on the scrotum and then on the lateral femoral soft tissue. Then the simple ratios of the scrotal and femoral soft tissue mean counts (S/Bg) were calculated. The statistical significance of differences among the groups in terms of scrotal uptake was determined. RESULTS: Group I showed increased scrotal uptake relative to the other groups. The mean uptake ratios (S/Bg±standard deviation) were 3.49±1.42 in group I, 2.89±0.70 in group II, 2.87±0.75 in group III, and 2.91±0.60 in group IV. This ratio was significantly higher in patients with prostate cancer than the normal group (P=0.024), the group with benign prostate hypertrophy (P=0.004), and the patients with other cancers (P=0.004). CONCLUSION: Our results showed that technetium-99m methylene diphosphonate bone scintigraphy, as a routine for detecting metastatic disease or performed for other purposes, could give clues for a hidden prostate cancer. Then, in elderly male patients, we strongly recommend that it is wise to keep one's eye on scrotal activity when bone scans are read and where there is any doubt, take appropriate regions of interest to make quantitative evaluations.

The value of different washout parameters in the evaluation of renal transplants by technetium-99m-ethylene- l-l-dicysteine.

Technetium-99m-ethylene-l-l-dicysteine ((99m)Tc-EC) is an agent with a potential for renal imaging. It is reported that EC uses the same tubular transporter system as ortho-hippurate (OIH) and mercaptoacetyltriglycine (MAG3) and that this agent has good imaging properties and higher renal clearance than MAG3. In this study we used (99m)Tc-EC to compare different washout parameters in renal transplanted patients. Sixty nine scans in 55 patients (38 males, 17 females) were performed with (99m)Tc-EC during the follow-up period after kidney transplantation. After bolus injection of 280MBq (99m)Tc-EC, 60x1sec and 29x1min images were taken in anterior position. Perfusions of transplanted kidneys were examined visually and perfusion indices (PI) were calculated according to Hilson's method. The semiquantitative washout parameters such as 20 and 30min to peak activity ratios and 20 and 30min to 3min activity ratios were calculated. The patients were clinically evaluated by nephrologists experienced in renal transplantation cases and followed-up by serum creatinine and blood urea nitrogen determinants which were checked every postoperative day until stabilized to a optimal level for each patient. Two standard deviations above the mean values derived from all cases with normal functioning transplanted kidneys were calculated for each method. Then, these values served as the threshold to differentiate the pathological cases respectively. Of the 69 total studies performed, we found 34 normal kidneys, 14 rejections, 19 acute tubular necrosis (ATN) and 2 cyclosporin A toxicity cases. The number of abnormal cases detected with 30/3min, 30/max, 20/3min and 20/max indices were 27, 26, 24, and 18, respectively. In conclusion, we strongly recommend in studying renal transplants to consider the activity at the 3(rd) min post injection as a reference point instead of the time to maximum activity for washout index calculation. If, for any reason the time to maximum counts using (99m)Tc-(peak activity) is prefered, then the period of study should not be performed for less than 30min to achieve reliable results.

Female breast surface radiation exposure during FDG PET/CT examinations.

BACKGROUND: The combined positron emission tomography (PET) and computed tomography (CT) scanners have been developed in which CT data can be used for both anatomical landmarks and attenuation correction of PET images. However, this modality potentially introduces more radiation burden to patients compared to conventional PET scanning as a result of the added radiation exposure received from CT examination. The purpose of our study was to determine the breast radiation doses of combined PET/CT examination. MATERIAL AND METHODS: Patients' superficial breast doses were calculated using thermoluminescence dosimeters (TLDs) placed onto the surface of the breasts. TLDs were positioned before FDG injection and removed after 24 h. We also determined the average superficial and glandular breast radiation doses from the anthropomorphic dosimetric phantom imaged using similar CT protocol (low dose) to the patients' study. RESULTS: The mean superficial breast dose of the breast skin measured from the PET/CT studies was 14.42+/-2.41 mGy. The average superficial and glandular breast doses of the anthropomorphic phantom measured from the low-dose CT was 9.50 mGy and 5.94 mGy, respectively. CONCLUSION: This study showed that radiation exposure to the breasts during PET/CT was higher than the recommended doses. Therefore, combined PET/CT scanning must be used for essential indications, particularly in women of reproductive age and preferentially a low-dose CT protocol should be implemented to avoid overexposure in such patients.

The relationship between pulmonary function tests, thorax HRCT, and quantitative ventilation-perfusion scintigraphy in chronic obstructive pulmonary disease.

We have evaluated the relationship between pulmonary function tests (PFT), thorax high resolution computed tomography (HRCT) images and quantitative ventilation-perfusion (V/Q) scintigraphic studies in 16 male patients (mean age 65.6 +/- 5.5 years) with chronic obstructive pulmonary disease (COPD). The mean forced vital capacity (FVC) value of the patient group was 2352 +/- 642 mL (65.4 +/- 15.8%), whereas mean forced expiratory volume in one second (FEV(1)) was found to be 1150 +/- 442 mL (40.8 +/- 14.9%). The ratio of carbon monoxide diffusion capacity to alveolar ventilation (DLCO/VA) was 3.17 +/- 0.88 mL/min/mmHg/L, and the mean partial oxygen (PaO(2)) and carbon dioxide (PaCO(2)) pressures were 68.5 +/- 11.04 mmHg and 38.9 +/- 5.8 mmHg respectively. For each patient, thorax HRCT and V/Q scintigraphic images of both lungs were divided into upper, mid and lower zones during examination. Visual scoring for the assessment of emphysema on thorax HRCT were used and images were graded from mild to severe (< or = 25% - > or = 76%). Emphysema scores were found to be higher on upper zones with accompanying lowest V/Q ratios. DLCO/VA, DLCO, total emphysema scores, and individual emphysema scores of the upper, mid and lower zones were found to be correlated. As a conclusion, it can be stated that emphysematous changes in COPD patients are more apparent in the upper lung zones, which also have the lowest V/Q ratios.