Comparison of 18F-FDG PET/CT and DW-MRI in assessment of neoadjuvant radiochemotherapy response in locally advanced rectal cancer patients. / Comparación de la PET/TC 18F-FDG y la DW-MRI en la evaluación de la respuesta a la radioquimioterapia neoadyuvante en pacientes con cáncer rectal localmente avanzado.

OBJECTIVE: Our aim is to evaluate if different metabolic parameters obtained by 18F-FDG PET/CT and diffusion weighted magnetic resonance imaging (DW-MRI) can aid in neoadjuvant radiochemotherapy (RCT) response assessment in locally advanced rectal cancer (LARC) patients. METHODS: Out of 20 LARC patients, who were planned to receive neoadjuvant RCT, 19 were included in this prospective study. Patients had 18F-FDG PET/CT and DW-MRI at initial staging, interim (2 weeks after onset of RCT) and after completion of RCT (post-therapy). Standardized uptake value (SUV) parameters (SUVmax, SUVmean, SUVpeak, SULpeak), metabolic tumor volume (MTV) and tumor lesion glycolysis (TLG) detected on PET images and apparent diffusion coefficient (ADC) values (for b=400 and b=1000s/mm2) obtained from DW-MRI were recorded. Postoperative tumor regression grade (TRG) was used as gold-standard, except for 2 patients who were under complete remission with non-operative management 19 months post-therapy and scored as responders. RESULTS: On interim PET/CT, no significant difference was found among PET parameters between responders and non-responders, whereas post-therapy SUVmax, SUVpeak, MTV, SULpeak, TLG (P=0.02, P=0.014, P=0.025, P=0.007, P=0.02, respectively) and initial MTV (P=0.034) were significantly lower in responders. ADC response index (RI) was higher in responders (interim P=0.026; post-therapy: P=0.018) and ROC analysis revealed that a threshold of ADC RI>41.6% for interim MRI and >44.6% for post-therapy MRI had sensitivity and specificity of 75.0% and 90.9%, respectively. CONCLUSIONS: While interim 18F-FDG PET/CT failed to predict therapy response during RCT, post-therapy PET could accurately differentiate responders. DW-MRI was found to be more promising in interim detection of RCT response.

Is it possible NET-redifferentiation after chemotherapy? 68Ga DOTA-peptide imaging as a game-changer in therapy management. / ¿Es posible la rediferenciación de NET tras la quimioterapia? Captación de imágenes de DOTA-péptidos marcados con 68Ga como cambio de estrategia en el tratamiento terapéutico.

A 64-year-old man with pancreatic grade III neuroendocrine carcinoma underwent 68Ga DOTANOC PET/CT scan for staging. The pancreatic lesion, multiple peripancreatic lymph nodes and multiple gross metastases in both hepatic lobes were revealed with intense uptake. After 3 cycles of chemotherapy containing cisplatin and etoposide the primary and metastatic lesions were decreased in size, however showing higher uptake on follow-up 68Ga DOTANOC PET/CT scan. Another biopsy from liver demonstrated a significant decrease in Ki-67 proliferation index from 35 to 1%. The patient received 2 cycles of peptide receptor-targeted radionuclide therapy with 177Lu DOTANOC.

Diagnostic impact of 18F-FDG PET/CT on the management of rare breast carcinomas: Apocrine and neuroendocrine carcinomas. / Impacto diagnóstico de la PET/TC con 18F-FDG en el tratamiento de carcinomas de mama raros: carcinomas apocrinos y neuroendocrinos.

OBJECTIVE: We aimed to evaluate the diagnostic impact of 18F-FDG PET/CT in staging apocrine breast carcinoma (ABC) and primary breast neuroendocrine carcinoma (PBNEC) and to demonstrate possible alterations of the 18F-FDG uptake in these histopathologic subtypes. In addition, we aimed to compare 18F-FDG PET/CT findings between ABC, PBNEC and invasive ductal carcinoma. MATERIAL AND METHODS: A total of 570 patients and 585 breast lesions were retrospectively included in this study. After patients were classified into molecular subtypes according to the histopathological analysis, 18F-FDG PET/CT imaging was performed. The SUVmax findings of primary tumors obtained from 18F-FDG PET/CT were compared between the groups. RESULTS: Invasive ductal carcinoma was the most prevalent breast carcinoma (77.7%, n=446), with a low proportion of ABC (4.1%, n=24) and PBNEC (2.4%; n=14) diagnosed. The highest mean SUVmax was calculated in HER2 subtype of ABC and 18F-FDG uptake ratio in HER2 and TN subtypes were found statistically higher than Luminal B type of ABC (p=0.038 and p=0.019, respectively). Although 18F-FDG uptake in Luminal B subtype of PBNEC was higher than Luminal A subtype, difference was not statistically significant. Additionally, the axillary metastasis rate was significantly higher in the ABC group (p=0.015). CONCLUSIONS: The histopathological ABC subtype group showed different 18F-FDG uptake than the invasive ductal carcinoma group. Even if 18F-FDG uptake was lower in the PBNEC group than in the other groups, PET/CT showed and adequate performance in detecting primary tumors and metastases. The 18F-FDG PET/CT scan results may contribute to the initial staging and management of ABC and PBNEC patients.

Assessment of alterations in regional cerebral blood flow in patients with hypothyroidism due to Hashimoto's thyroiditis.

AIM: The aim of this study was to assess regional cerebral blood flow (rCBF) using detailed semiquantitative analysis of Technetium-99m hexamethylpropyleneamine (HMPAO) brain single-photon emission computerized tomography (SPECT) in patients with hypothyroidism due to autoimmune thyroiditis. PATIENTS, MATERIAL AND METHODS: Twenty patients (mean age: 42+/-9 yr) and 12 control subjects (mean age: 35.4+/-8.5 yr) were included in this study. The corticocerebellar rCBF ratios were obtained from 52 cerebral areas on 6 transaxial slices. By using control group rCBF ratios, lower reference values (RLV) (average ratio -2 SD) were calculated and the regions below RLV having an rCBF ratio were considered as abnormal decrease (hypoperfused) areas. RESULTS: Significant reduced rCBF rates were measured for 15 (29%) cortical regions for the patient group. The areas in which significant reduced rCBF were demonstrated in the patient group were as follows: a) in the right hemisphere: superior frontal (slice 1 and 2), inferior frontal (slice 1), anterior temporal (slice 1 and 2), precentral gyrus (slice 1 and 2), postcentral gyrus (slice 1 and 2), and parietal cortex; b) in the left hemisphere: superior frontal (slice 1 and 2), inferior frontal (slice 1), caudate nucleus, and parietal cortex. The hypoperfusion was calculated in 154 (14%, 94 right and 60 left) cortical regions out of 1040 regions in the patient group. CONCLUSION: These findings indicate that the alteration of rCBF in patients with hypothyroidism due to Hashimoto's thyroiditis before T4 therapy can be demonstrated with brain SPECT. Additionally, the degree of rCBF abnormalities could be determined with brain SPECT in patients with hypothyroidism due to Hashimoto's thyroiditis with or without neurologic or psychiatric symptoms.

Evaluation of skeletal muscle metabolism and response to erythropoietin treatment in patients with chronic renal failure using 99Tcm-sestamibi leg scintigraphy.

It is well known that uraemia affects skeletal muscle metabolism. This has been attributed to a variety of causes, including anaemia, vitamin D, carnitine deficiency and hyperparathyroidism. The aim of this study was to ascertain whether 99Tcm-sestamibi leg scintigraphy is useful in the evaluation of skeletal muscle metabolism and the monitoring of treatment response in uraemic myopathy. Forty patients with chronic renal failure and 24 normal controls underwent examination. Fifteen patients with chronic renal failure received erythropoietin treatment. 99Tcm-sestamibi leg scintigraphy was performed in all subjects and in 15 patients after therapy. The calf-to-ankle uptake ratio was calculated by semi-quantitative analysis and normalized to lean body mass. The normalized uptake ratios were significantly different between patients and controls. After erythropoietin therapy, there was a significant increase in the normalized uptake ratios compared with pre-therapy. Our results suggest that 99Tcm-sestamibi leg scintigraphy is useful in the assessment of muscle metabolic abnormalities and the effect of treatment in uraemic myopathy.

The relationship between 99Tc(m)-sestamibi uptake and ultrastructural cell types of thyroid tumours.

Although several hypotheses have been suggested regarding the accumulation of 99Tc(m)-sestamibi in tumours, the exact uptake mechanism is still a matter of discussion. We investigated ultrastructural cell type of thyroid tumours by electron microscopy (EM) and compared them with uptake of 99Tc(m)-sestamibi. Thyroid scintigraphy with 99Tc(m)-sestamibi was performed on 25 patients who displayed a cold nodule on previous pertechnetate scintigraphy. Tumour-to-thyroid (T/N) uptake ratio was measured semiquantitatively. Surgery was performed in all patients and cytological evaluations were done by EM. Histopathology revealed six papillary carcinomas, 16 follicular adenomas and three Hurthle cell tumours. Thyroid cells were classified as A and B cells using EM. The cytoplasm of an A cell has the normal amount of mitochondria, whereas cytoplasm of a B cell (mitochondria-rich oxyphilic cell) contains abundant mitochondria. The median T/N ratio on the early scan for an A-cell tumour was 1.21 (range, 0.74-3.2), late T/N ratio was 1.25 (range, 0.72-3.85). The T/N ratio for the B-cell tumours was 1.42 (range, 0.6-3.6) on the early scan and 1.18 (range, 0.64-5.58) on the late scan. There was no statistically significant difference between T/N ratios of A- and B-cell tumour groups. A significant difference was also not seen between early and late T/N ratios. According to our findings, 99Tc(m)-sestamibi accumulates in thyroid tumours with both A and B cells, therefore these results suggest that the mitochondrial content of tumours is not only responsible for sestamibi uptake and retention.

Role of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography in diagnosis and management of pancreatic cancer; comparison with multidetector row computed tomography, magnetic resonance imaging and endoscopic ultrasonography.

OBJECTIVES: We aimed to analyze the contribution of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging to the diagnosis and management of pancreatic cancer compared with multidetector row computed tomography (MDCT), magnetic resonance imaging (MRI) and endoscopic ultrasonography (EUS). MATERIAL AND METHODS: We retrospectively scanned the data of 52 patients who were referred for FDG PET/CT imaging for evaluation of pancreatic lesions greater than 10mm. The diagnostic performances of 4 imaging methods and the impact of PET/CT on the management of pancreatic cancer were defined. RESULTS: Pancreatic adenocarcinoma was diagnosed in 33 of 52 patients (63%), 15 patients had benign diseases of pancreas (29%), and 4 patients were normal (8%). Sensitivity and NPV of EUS and PET/CT were equal (100%) and higher than MDCT and MRI. Specificity, PPV and NPV of PET/CT were significantly higher than MDCT. However, sensitivities of two imaging methods were not significantly different. There was no significant difference between PET/CT and MRI and EUS for these values. When the cut-off value of SUVmax was 3.2, the most effective sensitivity and specificity values were obtained. PET/CT contributed to the management of pancreatic cancer in 30% of patients. CONCLUSION: FDG PET/CT is a valuable imaging method for the diagnosis and management of pancreatic cancer, especially when applied along with EUS as first line diagnostic tools.

99mTc-HMPAO labelled white blood cell scintigraphy in the diagnosis and monitoring of response of the therapy in patients with active bronchiectasis.

AIM: The aim of this study was to assess the role of labelled leukocyte scintigraphy in the diagnosis and monitorization of response to therapy of patients with active bronchiectasis. MATERIAL AND METHODS: Twenty patients underwent (99m)Technetium hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) labelled white blood cell (WBC) scintigraphy. A second scintigraphy was performed in 13 patients at 10 day of the treatment. Regional (99m)Tc-HMPAO WBC uptake and radiologic imaging findings (high resolution computed tomography or Chest X-Ray) in the lungs were classified into 3 categories in 6 lung areas. scintigraphic, radiological and clinical disease scores were calculated for all patients. RESULTS: An abnormal accumulation was visually observed in 19 of 20 patients on the pre-treatment scans, the scintigraphy showing 95% sensitivity. A significant difference was found between early and late ratios (P=0.001) in the pre-treatment scans. The infected areas revealed a significant decrease in uptake ratios on the post-treatment scans compared to the pre-treatment scans (P=0.001). However, no significant correlation was determined between clinical and radiological scores, clinical and scintigraphic scores and also between scintigraphic and radiological scores (P ≥ 0.05). CONCLUSIONS: (99m)Tc-HMPAO WBC scintigraphy may be a useful tool to evaluate response to therapy in patients with active bronchiectasis.

Monitoring of renal function using 99mTc-DMSA and 99mTc-DTPA scintigraphy in patients with spinal cord injury.

AIM: The aim of this study was to assess the degree of alterations of renal function by using 99m-technetium dimercaptosuccinic acid ((99m)Tc-DMSA) and 99m-technetium diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) scintigraphy in spinal cord injury (SCI) patients. MATERIAL AND METHODS: Twenty-two consecutive SCI (15 paraplegic and 7 tetraplegic) patients (mean age: 49.1±13.4 years) who had no urinary symptoms participated in this prospective study. The mean duration of injury was 45.6±48.8 months before. Sixteen patients had at least one urinary tract infection history. Renal cortical scintigraphy with (99m)Tc-DMSA, radionuclide renography with (99m)Tc-DTPA and renal ultrasound were performed within 2-week period. RESULTS: Four (18%) patients had serious pathology on their kidneys such as unilateral or bilateral parenchymal scarring and increased background uptake in their renal cortical scintigraphy with (99m)Tc-DMSA. Two of them had grade 3-4 pelvicaliceal ectasia on ultrasound. Additionally, 2 of 18 remaining patients had grade 2 pelvicaliceal ectasia on ultrasound. Sixteen (73%) patients had markedly delayed or delayed and decreased functions of one or both of kidneys on radionuclide renography. However, only four patients had grade 2-4 pelvicaliceal ectasia and none of them had a finding of loosening of renal parenchyma. CONCLUSION: Combined use of renal cortical scintigraphy and radionuclide renography appears to be contributive to renal ultrasound in the long-term follow-up of patients with SCI. Patients with abnormal findings should be closely followed, and early therapeutic interventions may enable lower morbidity and mortality rates in these patients.

Evaluation of dysthymic disorder with technetium-99 m hexamethylpropylene amine oxime brain single-photon emission tomography.

Dysthymic disorder is a chronic disorder characterised by the presence of a depressed mood and is classified as a distinct category in DSM-IV, separately from major depression. Although brain imaging studies have been performed in major depressive disease, there have to date been no reports of such studies in dysthymic disorder. In this study 36 patients with dysthymic disorder were compared with 16 normal subjects using technetium-99m hexamethylpropylene amine oxime brain single-photon emission tomography. A relative blood flow ratio was calculated for each region of interest using the average tissue activity in the region divided by activity in the cerebellum. There were significant differences in the bilateral inferior frontal, bilateral parietal, right superior frontal and left posterior temporal regions in the patients with dysthymic disorder compared with the healthy controls. These findings support the hypothesis that the biological bases for dysthymic disorder and major depression are similar. Recognition of these regional abnormalities may have clinical utility in both the diagnosis and the treatment of dysthymic disorder. Further studies are needed to confirm our results and to assess the influence of treatment in patients with dysthymic disorder.

Monitoring the chemotherapeutic response in primary lung cancer using 99mTc-MIBI SPET.

Prediction and evaluation of the response to chemotherapy (CTx) are important for the correct and cost-effective treatment of patients with primary lung cancer. Although fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is accepted as the most useful and accurate nuclear medicine technique for this purpose, its expense and limited availability restrict its use. Compared with PET agents, technetium-99m methoxyisobutylisonitrile (MIBI), which is used in nuclear oncology, is cheaper and available in any nuclear medicine clinic. With this in mind, in this study we aimed to evaluate the role of 99mTc-MIBI in monitoring the chemotherapeutic response in primary lung cancer. Twenty patients with primary lung cancer underwent 99mTc-MIBI single-photon emission tomography (SPET) at 15 min (early) and 3-4 h (delayed) after injection of the tracer. All patients underwent 99mTc-MIBI SPET study twice: before and after the 3rd cycle of CTx. Patients were divided into two groups, responders [R(+), n=10] and nonresponders [R(-), n=10], according to the change in tumour size on CT scan taken 2 weeks after the last cycle of the CTx. From the SPET images early and delayed tumour/lung ratios (ER and DR) were obtained before and after CTx. In the R(+) group, ER and DR decreased significantly after CTx, from 3.28+/-1.55 to 1.78+/-0.72 (P<0.04) and from 3.23+/-1.55 to 2.0+/-0.88 (P<0.05), respectively. However, in the R(-) group, while ER showed a slight and statistically insignificant increase after CTx (from 2.51+/-1.23 to 2.65+/-1.86), DR increased significantly, from 2.74+/-1.37 to 3.27+/-2.31 (P<0.03). The percentage decreases in ER and DR in the R(+) group after CTx was significantly higher than that in the R(-) group: 34.36%+/-26.7% vs -13.78%+/-27.58% (P<0.0002) and 29.45%+/-25.23% vs -18.58%+/-20.51% (P<0.0005), respectively. Using a decrease of > or =10% as a threshold for monitoring the chemotherapeutic response, 99mTc-MIBI had a sensitivity of 90% and a specificity of 100%. We found a positive correlation in 14 patients between ER and DR and survival: r=0.6754 and P=0.008, and r=0.5755 and P=0.031, respectively. Our results suggest that 99mTc-MIBI might be used in routine practice to monitor the chemotherapeutic response in patients with primary lung cancer, especially when PET is not available.