The value of PET/CT for the diagnosis and evaluation of immunotherapy in occult primary renal cell carcinoma: a case report.

Skin and soft tissue diffusion metastasis (also known as occult cancer) is rare in renal cell carcinoma (RCC). Here, we report an extremely rare case of a 67-year-old male patient with occult primary RCC who developed metastases to the gums, skin, and diffuse soft tissue. The primary renal lesion was missed by computed tomography (CT), ultrasound, and 18F-fluorodeoxyglucose positron emission tomography (PET)/CT, and the diagnosis was confirmed by biopsy of gums and subcutaneous nodules. Subsequent enhanced CT revealed a lesion in the left kidney. The patient had progression-free survival of 16 months after treatment with axitinib and pembrolizumab. Pseudoprogression and tumor heterogeneity pose major challenges in the evaluation of immunotherapy. PET/CT is indispensable especially for cases with multiple metastases, widespread distribution of lesions, and major heterogeneity. In this case, the total lesion glycolysis was calculated by PET/CT and was used to evaluate systemic tumor load before and after immunotherapy, which was calculated as the product of the metabolic tumor volume and the mean standardized uptake value of the target lesion, which increased the accuracy of assessing diffuse lesions. Total lesion glycolysis can be used as a new method to quantitatively evaluate the efficacy of immunotherapy.

Impact of misregistration between SPECT and CT on attenuation correction of myocardial perfusion imaging / 中华核医学与分子影像杂志

Objective To evaluate the effects of misregistration with different directions and magnitudes between SPECT and CT on image quality and semi-quantification of MPI.Methods The data of 19 healthy volunteers (11 males,8 females ; mean age:(65.3 ± 9.6) years) were retrospectively analyzed.They all had a low pretest likelihood of coronary artery disease according to exercise and rest 99Tcm-MIBI MPI.The CT attenuation correction (CTAC) was performed on a SPECT/CT system.The CT images were manually shifted by 0.5,1.0,1.5,2.0,2.5,3.0,3.5,4.0,4.5 cm distance along the up/down,left/ right,and anterior/posterior axes respectively by using the system built-in software.The counts of the left ventricle were measured using myocardial Bull's eye generated from the reconstructed CTAC images.The image quality and semi-quantification of the CTAC images reconstructed from the raw data with and without shifting were compared and analyzed.Paired t test was used to analyze the data.Results There was no visible artifact with 0.5 cm shifting.The image quality was deteriorated significantly and the counting difference was significant with shifting distance greater than or equal to 1.0 cm.The image artifact of apex wall was mainly due to the upward shift,anterior and apex wall due to the downward shift,septal wall due to the leftward shift,anterior,apex and lateral wall due to the rightward shift,lateral and infero-posterior wall due to the forward shift,anterior,apex and septal wall due to backward shift.The counting difference caused by the downward shift was significantly more severe than that caused by the upward shift ((-9.68±8.06) ％ and (-2.04±1.83)％,t=6.573,P＜0.01) ; and the rightward shift was more severe than the leftward shift ((-9.02± 8.47) ％ and (-4.38±3.67) ％ ; t =1.987,P＜0.05).The image artifacts in anterior,apex and lateral walls were more severe than those in the infero-posterior and septal walls.Conclusions CTAC image artifacts in myocardial perfusion SPECT/CT studies could be caused by misregistration ≥ 1.0 cm.Different directions and magnitudes of shift could result in different degrees of attenuation artifacts at different locations on the original images.

The value of right lateral decubitus position to decrease artificial defect of cardiac anterior wall in 99Tcm-MIBI SPECT myocardial perfusion imaging for women / 中华核医学与分子影像杂志

Objective To explore the value of right lateral decubitus position MPI for differentiating myocardial perfusion defect from cardiac anterior wall attenuation artificial defect,caused by breast of woman.Methods Forty-nine patients(average age (61.5±8.4) years) who had low likelihood of coronary artery disease and had perfusion defect in the anterior wall after exercise stress 99Tcm-MIBI MPI were included.All underwent supine and right lateral decubitus position during resting SPECT images.The myocardial perfusion SPECT images at left ventricle were reconstructed and were measured by Bull's-eye,based on the counts.Results from both supine position imaging and right lateral decubitus position imaging were compared.Paired t test was used to statistically analyse the data by SPSS 13.0.Results Compared with supine position,the counts of the anterior,inferior,apex and lateral wall in right lateral decubitus position were significantly higher:(71.30±3.53) ％ vs (66.50±3.85) ％,(70.06±4.45) ％ vs (65.44±4.16) ％,(77.90±3.00)％ vs (75.81±4.08)％,(79.30±2.26)％ vs (72.60±3.87)％ (t=6.731,5.286,3.555,10.885,all P＜0.01).The counts of septal wall were significantly lower ((66.60±3.98)％ vs (70.06±4.51)％,t=-4.625,P＜0.01) in right lateral decubitus position than that in supine position.Among the different regions of anterior wall,the counts of the anterior-middle ((76.40 ± 3.80) ％ vs (68.60 ± 4.76) ％) and anterior-apex region ((77.10±3.24) ％ vs (69.00±3.54) ％) were significantly higher (t =9.916,8.870,both P＜0.01) in right lateral decubitus position than those in supine position,but there was insignificance ((56.94±6.06)％ vs (58.50±4.98) ％,t =-1.493,P＞0.05) at anterior-basal region.The artificial defect of different degrees in anterior wall was observed in all patients in supine position,23 cases (46.9％,23/49) showed artificial defect in the anterior-middle region and 16 cases (32.7％,16/49) in the anterior-apex region.All artificial defect showed radioactive filling in right lateral position imaging,12 cases(24.5％,12/49) filled markedly and 32 cases(65.3％,32/49) filled completely.Conclusions The artificial defects caused by breast of woman mainly present in anterior-middle region and in anterior-apex region of the anterior wall in supine position imaging.The right lateral decubitus position imaging can markedly improve these artificial defects.

Comparison of the different reconstruction algorithms for Philips GEMINI PET/CT / 中国医学影像技术

Objective To evaluate the effects of different reconstruction algorithms on image quality for Philips GEMINI PET/CT. Methods Jaszczak phantom were scanned on the GEMINI PET/CT system, and the raw data were reconstructed using filtered-back projection with Hanning filter (FBP-Hanning), filtered-back projection with Butterworth filter (FBP-Butterworth), ordered subset expectation maximization (OSEM), row-action maximum likelihood algorithm (RAMLA) and three-dimensional row-action maximum likelihood algorithm (3D-RAMLA), respectively. The resolution, uniformity, contrast of images and the time of different reconstruction algorithms were compared. Results The reconstruction time was 180 s, 130 s, 120 s, 85 s and 80 s for 3D-RAMLA, RAMLA, OSEM, FBP-Hanning and FBP-Butterworth respectively in phantom studies. The smallest rods with diameter of 4.8 mm of the phantom could be observed for FBP- Butterworth and 6.4 mm for other algorithms in case of high counts. The image contrast of 3D-RAMLA were better than that other algorithms, and the image uniformity of 3D-RAMLA and RAMLA were better than those of other algorithms. The resolution, uniformity and contrast of images with all algorithms decreasd in case of low counts, and the image quality of FBP-Butterworth was not good enough for clinical studies. Conclusion Image quality is variable with different reconstruction algorithms. For clinical PET imaging, it is necessary to choose proper algorithms.

Applications of 18F-Fluorodexyglucose Positron Emission Tomography on the Diagnosis and Treatment of Carcinoma of Large Intestine / 中国普外基础与临床杂志

Objective To introduce the current study on 18F-fluorodexyglucose positron emission tomography (18F-FDG PET) scanning in diagnosis and treatment of carcinoma of large intestine.Methods The literatures about 18F-FDG PET scanning in diagnosis and treatment of carcinoma of large intestine in recent years were reviewed.Results 18F-FDG PET scanning is superior to CT and MRI in identificating carcinoma of large intestine recurrence, metastasis in the early stage after operation and staging carcinoma of large intestine.Conclusion 18F-FDG PET scanning may be one of the accessory examinations in carcinoma of large intestine and may be helpful for the choice of treatment.