PSMA PET/CT imaging and its application to prostate cancer treatment.

Recognition of the importance of prostate-specific membrane antigen (PSMA) PET/CT in the diagnosis of prostate cancer has steadily increased following the publication of extensive data on its diagnostic accuracy and impact on patient management over the past decade. Several recent clinical trials and investigations regarding PSMA PET/CT have been ongoing in our country, and this examination is expected to become increasingly widespread in the future. This review explains the characteristics of PSMA PET/CT, its diagnostic capabilities and superiority over other modalities, the three proposed PSMA PET/CT interpretation criteria (the European Association of Nuclear Medicine [EANM], the Prostate Cancer Molecular Imaging Standardized Evaluation [PROMISE], and the PSMA Reporting and Data System [PSMA-RADS]), and the application of PSMA PET/CT to prostate cancer treatment (improvement of local control, irradiation of oligometastases, and salvage radiotherapy), incorporating actual clinical images and the latest findings.

18F-FDG PET/CT Imaging of G-CSF-Producing Inflammatory Myofibroblastic Tumor of the Pleura.

ABSTRACT: We report a case of granulocyte colony-stimulating factor (G-CSF)-producing inflammatory myofibroblastic tumor of the pleura in a 71-year-old man. Contrast-enhanced CT demonstrated multiple pleural masses with pulmonary hilar lymph nodes swelling. 18F-FDG PET/CT demonstrated marked focal FDG uptake in the thoracic masses with diffuse uptake in the bone marrow. Based on the pathological findings and elevated serum G-CSF level, the patient was diagnosed as G-CSF-producing inflammatory myofibroblastic tumor. Because G-CSF-producing tumors demonstrate aggressive clinical course, early and accurate diagnosis is important.

18F-FDG PET/CT Findings of G-CSF-Producing Gallbladder Cancer.

ABSTRACT: We report a case of granulocyte colony-stimulating factor (G-CSF)-producing gallbladder cancer in a 64-year-old man. Contrast-enhanced CT showed an exophytic hypoattenuation mass with peripheral enhancement in the gallbladder. 18F-FDG PET/CT showed avid FDG uptake in the gallbladder mass and diffuse FDG uptake in the bone marrow. The patient was diagnosed with G-CSF-producing gallbladder cancer based on an elevated serum level of G-CSF and histological findings. G-CSF-producing tumors are associated with a poor prognosis because of rapid progression. Early and accurate diagnosis of G-CSF-producing tumors based on characteristic PET/CT findings is important to determine treatment strategies and improve prognosis of patients.

Differentiation of uterine low-grade endometrial stromal sarcoma from rare leiomyoma variants by magnetic resonance imaging.

The purpose of this study is to evaluate utility of MRI in differentiation of uterine low-grade endometrial stromal sarcoma (LGESS) from rare leiomyoma variants. This multi-center retrospective study included consecutive 25 patients with uterine LGESS and 42 patients with rare leiomyoma variants who had pretreatment MRI. Two radiologists (R1/R2) independently evaluated MRI features, which were analyzed statistically using Fisher's exact test or Student's t-test. Subsequently, using a five-point Likert scale, the two radiologists evaluated the diagnostic performance of a pre-defined MRI system using features reported as characteristics of LGESS in previous case series: uterine tumor with high signal intensity (SI) on diffusion-weighted images and with either worm-like nodular extension, intra-tumoral low SI bands, or low SI rim on T2-weighted images. Area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of the two readers' Likert scales were analyzed. Intra-tumoral low SI bands (p < 0.001), cystic/necrotic change (p ≤ 0.02), absence of speckled appearance (p < 0.001) on T2-weighted images, and a low apparent diffusion coefficient value (p ≤ 0.02) were significantly associated with LGESS. The pre-defined MRI system showed very good diagnostic performance: AUC 0.86/0.89, sensitivity 0.95/0.95, and specificity 0.67/0.69 for R1/R2. MRI can be useful to differentiate uterine LGESS from rare leiomyoma variants.

Neuroendocrine carcinoma of uterine cervix findings shown by MRI for staging and survival analysis - Japan multicenter study.

OBJECTIVES: To investigate neuroendocrine carcinoma (NEC) of the uterine cervix cases for MRI features and staging, as well as pathological correlations and survival. RESULTS: FIGO was I in 42, II in 14, III in 1, and IV in 5 patients. T2-weighted MRI showed homogeneous slightly high signal intensity and obvious restricted diffusion (ADC map, low intensity; DWI, high intensity) throughout the tumor in most cases, and mild enhancement in two-thirds. In 50 patients who underwent a radical hysterectomy and lymphadenectomy without neoadjuvant chemotherapy (NAC), intrapelvic T staging by MRI overall accuracy was 88.0% with reference to pathology staging, while patient-based sensitivity, specificity, and accuracy for metastatic pelvic lymph node detection was 38.5%, 100%, and 83.3%, respectively. During a mean follow-up period of 45.6 months (range 4.3-151.0 months), 28 patients (45.2%) experienced recurrence and 24 (38.7%) died. Three-year progression-free and overall survival rates for FIGO I, II, III, and IV were 64.3% and 80.9%, 50% and 64.3%, 0% and 0%, and 0% and 0%, respectively. MATERIALS AND METHODS: Sixty-two patients with histologically surgery-proven uterine cervical NEC were enrolled. Twelve received NAC. Clinical data, pathological findings, and pretreatment pelvic MRI findings were retrospectively reviewed. Thirty-two tumors were pure NEC and 30 mixed with other histotypes. The NECs were small cell type (41), large cell type (18), or a mixture of both (3). CONCLUSIONS: Homogeneous lesion texture with obvious restricted diffusion throughout the tumor are features suggestive of cervical NEC. Our findings show that MRI is reliable for T staging of cervical NEC.

Invasive solid papillary carcinoma with neuroendocrine differentiation of the breast: a case report and literature review.

BACKGROUND: Solid papillary carcinoma (SPC) of the breast is a rare breast cancer that accounts for less than 1% of all breast cancers. The optimal clinical management of SPC remains controversial. Here, we report a case of invasive SPC with neuroendocrine differentiation in addition to review of the current literature. CASE PRESENTATION: A premenopausal 46-year-old female presented with a mass in her left breast that tended to increase in size over a 10-month period. Mammography and ultrasonography revealed a mass in the left upper-inner quadrant. The resulting images suggested a category 3 breast tumor according to the Breast Imaging Reporting and Data System (BI-RADS). A core needle biopsy (CNB) was performed, and the pathological findings showed a solid papillary pattern and atypical cells suggestive of noninvasive SPC. After a left partial mastectomy and sentinel lymph node biopsy (SLNB), the specimens were sent for histopathological analysis for further investigation. Postoperative pathological findings suggested invasive SPC. Whole-breast radiation therapy and adjuvant hormonal therapy were performed as postoperative treatments. Three years after surgery, multiple lung metastases were detected, and the patient was treated with a gonadotropin-releasing hormone agonist and an aromatase inhibitor. Five months later, multiple liver metastases and bone metastases appeared, and oral 5-fluorouracil was chosen for the subsequent treatment. The patient has been treated for 5 years to date, and she is continuing to take oral 5-fluorouracil and is alive without any further disease progression. CONCLUSIONS: We report a rare case of premenopausal invasive SPC with multiple metastases. Further study is needed to clarify the molecular characteristics and clinical behaviors of SPC and to explore the optimal treatment strategy.

Diagnostic performance of chest CT to differentiate COVID-19 pneumonia in non-high-epidemic area in Japan.

PURPOSE: To evaluate the diagnostic performance of chest CT to differentiate coronavirus disease 2019 (COVID-19) pneumonia in non-high-epidemic area in Japan. MATERIALS AND METHODS: This retrospective study included 21 patients clinically suspected COVID-19 pneumonia and underwent chest CT more than 3 days after the symptom onset: six patients confirmed COVID-19 pneumonia by real-time reverse-transcription polymerase chain reaction (RT-PCR) and 15 patients proved uninfected. Using a Likert scale and its receiver operating characteristic curve analysis, two radiologists (R1/R2) evaluated the diagnostic performance of the five CT criteria: (1) ground glass opacity (GGO)-predominant lesions, (2) GGO- and peripheral-predominant lesions, (3) bilateral GGO-predominant lesions; (4) bilateral GGO- and peripheral-predominant lesions, and (5) bilateral GGO- and peripheral-predominant lesions without nodules, airway abnormalities, pleural effusion, and mediastinal lymphadenopathy. RESULTS: All patients confirmed COVID-19 pneumonia had bilateral GGO- and peripheral-predominant lesions without airway abnormalities, mediastinal lymphadenopathy, and pleural effusion. The five CT criteria showed moderate to excellent diagnostic performance with area under the curves (AUCs) ranging 0.77-0.88 for R1 and 0.78-0.92 for R2. The criterion (e) showed the highest AUC. CONCLUSION: Chest CT would play a supplemental role to differentiate COVID-19 pneumonia from other respiratory diseases presenting with similar symptoms in a clinical setting.

Assessment of treatment response after lung stereotactic body radiotherapy using diffusion weighted magnetic resonance imaging and positron emission tomography: A pilot study.

BACKGROUND AND PURPOSE: There is no early predictor of treatment response after lung stereotactic body radiotherapy (SBRT). We conducted this pilot study to evaluate whether serial diffusion weighted magnetic resonance imaging (DW-MRI) or positron emission tomography (PET) could predict response after SBRT. MATERIAL AND METHODS: Early stage non-small cell lung cancer patients who received SBRT were eligible. DW-MRI and PET were undertaken pretreatment and every 3 months after SBRT in the first year. Patients with <1year of follow-up were excluded from the analysis. The apparent diffusion coefficient (ADC) value and maximum standardized uptake value (SUVmax) of tumors were measured and compared between groups with or without local recurrence (LR). RESULTS: Fifteen patients were enrolled and the data of 14 patients were analyzed. The median ADC value was significantly lower in patients with LR (n=3) than in those without LR (n=11) at 3 and 6 months (1.11 vs. 1.54 and 0.98 vs. 1.69 [×10-3mm2/s]; p=0.039 and 0.012, respectively) while there was no significant difference pretreatment and at 9 and 12 months after treatment. No significant difference was observed in the SUVmax at any time point. CONCLUSIONS: DW-MRI could be an early predictor of treatment response after lung SBRT.

Predictive value of radiological response rate for pathological response to neoadjuvant chemotherapy and post-cystectomy survival of bladder urothelial cancer.

OBJECTIVE: To determine the predictive value of the radiological response rate assessed by serial pelvic computed tomography scans for pathological response to neoadjuvant chemotherapy and clinical outcomes after radical cystectomy in bladder urothelial cancer patients. METHODS: We retrospectively reviewed 59 patients with muscle-invasive bladder cancer who underwent radical cystectomy following neoadjuvant chemotherapy. Pretreatment and post-neoadjuvant chemotherapy computed tomography scans were evaluated by a single radiologist to determine the radiological response rate based on the largest diameter of the primary tumor. Association of the radiological response rate with pathological findings of the radical cystectomy specimen and post-radical cystectomy clinical outcomes were assessed. RESULTS: The pathological complete response rate was 25% (n = 15) and the median (range) radiological response rate was 0.58 (0.00-1.00). The radiological response rate was significantly associated with ≤pT1. Patients with pathological downstaging to ≤pTa/is or pT1, compared with those with pT2≤ tumor, had significantly better post-radical cystectomy recurrence-free survival (2-year survival 92.0, 88.9, 36.8%, respectively, P < 0.0001), disease-specific survival (2-year survival 95.8, 88.9, 47.3%, respectively, P < 0.0001) and overall survival (2-year survival 91.7, 88.9, 40.1%, respectively, P < 0.0001). Patients with a higher radiological response rate (≥0.57) had significantly better post-radical cystectomy recurrence-free survival (2-year survival 89.7 vs. 48.1%, P = 0.0011), disease-specific survival (2-year survival 93.2 vs. 48.2%, P < 0.0001) and overall survival (2-year survival 90.0 vs. 39.0%, P < 0.0001). Multivariate analyses using the Cox proportional hazard model revealed that the radiological response rate was an independent predictor for favorable pT stage and recurrence-free survival. CONCLUSION: The radiological response rate determined by pretreatment and post-chemotherapy computed tomography scans predicts the pathological outcome and post-radical cystectomy prognosis, which is clinically relevant and useful for patient counselling and decision-making.

A multicenter, randomized, controlled, single-blind comparison phase III study to determine the efficacy and safety of gadobutrol 1.0 M versus gadopentetate dimeglumine following single injection in patients referred for contrast-enhanced MRI of the body regions or extremities.

PURPOSE: To demonstrate the noninferiority of gadobutrol-enhanced magnetic resonance imaging (MRI) compared with gadopentetate dimeglumine-enhanced MRI in Asian patients referred for contrast-enhanced imaging of the body or extremities. MATERIALS AND METHODS: A multicenter, parallel-group comparison study of Asian adults referred for contrast-enhanced MRI were randomized (1:1) to either gadobutrol or gadopentetate dimeglumine. Lesions were assessed for three primary visualization variables: degree of contrast enhancement, border delineation, and internal morphology. Secondary efficacy variables included number of lesions detected, match of MRI diagnosis with final clinical diagnosis, and sensitivity and specificity for malignant lesion detection. Safety was monitored for 24 ± 4 hours after contrast agent administration. RESULTS: A total of 363 patients received either gadobutrol (n = 168) or gadopentetate dimeglumine (n = 178). Mean total scores for three primary visualization variables were 9.39 and 9.34 for gadobutrol and gadopentetate dimeglumine, respectively. The proportion of patients with matched MRI and final diagnosis and sensitivity for malignant lesion detection was greater for unenhanced versus combined images (gadobutrol: 72.2% vs. 81.7%; gadopentetate dimeglumine: 76.2% vs. 82.2%, respectively). Both contrast agents were well tolerated. CONCLUSION: Gadobutrol (0.1 mmol/kg BW) was well tolerated and effective in Asian patients referred for contrast-enhanced MRI of the body or extremities.

Prediction of clinical outcome after stereotactic body radiotherapy for non-small cell lung cancer using diffusion-weighted MRI and (18)F-FDG PET.

PURPOSE/OBJECTIVES: To evaluate the use of diffusion-weighted magnetic resonance imaging (DW-MRI) and (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for predicting disease progression (DP) among patients with non-small cell lung carcinoma (NSCLC) treated with stereotactic body radiotherapy (SBRT). MATERIALS/METHODS: Fifteen patients with histologically confirmed stage I NSCLC who underwent pre-treatment DW-MRI and PET and were treated with SBRT were enrolled. The mean apparent diffusion coefficient (ADC) value and maximum standardised uptake value (SUVmax) were measured at the target lesion and evaluated for correlations with DP. RESULTS: The median pre-treatment ADC value was 1.04×10(-3) (range 0.83-1.29×10(-3))mm(2)/s, and the median pre-treatment SUVmax was 9.9 (range 1.6-30). There was no correlation between the ADC value and SUVmax. The group with the lower ADC value (≤1.05×10(-3)mm(2)/s) and that with a higher SUVmax (≥7.9) tended to have poor DP, but neither trend was statistically significant (p=0.09 and 0.32, respectively). The combination of the ADC value and SUVmax was a statistically significant predictor of DP (p=0.036). CONCLUSION: A low ADC value on pre-treatment DW-MRI and a high SUVmax may be associated with poor DP in NSCLC patients treated with SBRT. Using both values in combination was a better predictor.

The clinical utility of reduced-distortion readout-segmented echo-planar imaging in the head and neck region: initial experience.

OBJECTIVES: To evaluate whether readout-segmented echo-planar imaging (RS-EPI) diffusion weighted image (DWI) can diminish image distortion in the head and neck area, compared with single-shot (SS)-EPI DWI. METHODS: We conducted phantom and patient studies using 3 T magnetic resonance imaging (MRI) with a 16-channel coil. For the phantom study, we evaluated distortion and signal homogeneity in gel phantoms. For the patient study, 29 consecutive patients with clinically suspicious parotid lesions were prospectively enrolled. RS-EPI and SS-EPI DWI were evaluated by two independent readers for identification of organ/lesion and distortion, using semiquantitative scales and quantitative scores. Apparent diffusion coefficient (ADC) values and contrast-noise ratios of parotid tumours (if present; n = 15) were also compared. RESULTS: The phantom experiments showed that RS-EPI provided less distorted and more homogeneous ADC maps than SS-EPI. In the patient study, RS-EPI was found to provide significantly less distortion in almost all organs/lesions (p < 0.05), according to both semiquantitative scales and quantitative scores. There was no significant difference in ADC values and contrast-noise ratios between the two DWI techniques. CONCLUSIONS: The distortion in DWI was significantly reduced with RS-EPI in both phantom and patient studies. The RS-EPI technique provided more homogenous images than SS-EPI, and can potentially offer higher image quality in the head and neck area. KEY POINTS: The distortion in DWI is significantly reduced with RS-EPI compared with SS-EPI. Structures in the head and neck were identified more clearly using RS-EPI. No significant difference in ADC values was found between the techniques.

Decidualized adenomyosis during pregnancy and post delivery: three cases of magnetic resonance imaging findings.

Adenomyosis is a common gynecologic disease. Pregnancy with adenomyosis is on the increase due to a tendency of delay with first pregnancies and various infertility treatments involved in the process. We encountered decidualized adenomyosis in three patients during pregnancy, who were suspected by magnetic resonance (MR) imaging and were followed monitored post delivery. The MR imaging findings of adenomyosis during pregnancy showed low signal intensity areas with embedded bright foci that expanded to a few mm in diameter on half Fourier single-shot turbo spin-echo images. This finding may reflect decidual change of the stroma within the ectopic endometrium caused during pregnancy. The MR imaging findings of adenomyosis after childbirth showed hemorrhage inside the lesion, which were assumed to be led by rapid decrease in a blood flow to adenomyosis post childbirth.

"Early esophageal rim enhancement": a new sign of esophageal cancer on dynamic CT.

OBJECTIVE: To retrospectively assess a new CT finding of esophageal cancer, "early esophageal rim enhancement". MATERIALS AND METHODS: Sixty-two patients with pathological proven esophageal squamous cell carcinoma who underwent dual phase CT imaging (arterial and venous phases) were enrolled. Two blinded observes independently evaluated presence of partial or circumferential enhancement of the esophageal periphery on arterial (early esophageal rim enhancement) and venous phase CT images. The radiological assessment was compared with the pathological T-stages. Agreement between the observers was also evaluated with a Cohen' kappa value. RESULTS: Pathologic results found 19, 12, 30 and 1 lesions, respectively for T1, T2, T3 and T4 stages. Agreement between two readers was substantial (κ=0.71). Esophageal rim enhancement was observed in 0, 4, 24 and 1 lesions respectively for T1, T2, T3 and T4 stages at the arterial phase, whereas no esophageal rim enhancement could be detected at the venous phase. Early esophageal rim enhancement was more frequently observed in T3/T4 lesions than T1/T2 lesions with statistical significance (p<0.0001). The sensitivity, specificity and accuracy for the diagnosis of T3 or T4 lesion were 80.6%, 87.1% and 83.9%, respectively. CONCLUSION: Early esophageal rim enhancement may be helpful for assessing invasion into the adventitia.

Non-contrast-enhanced MR venography of the upper limb: a comparative study of acquisitions with fresh blood imaging vs. time-of-flight methods.

Non-contrast-enhanced magnetic resonance venography (MRV) of the upper limb acquired by fresh blood imaging (FBI) was compared with time-of-flight (TOF)-MRV. Visualization of three veins (basilic, brachial, and cephalic veins), small branches, and fat suppression was evaluated with a four-point scale (0-3). FBI-MRV was significantly superior for the basilic veins and small venous branches and equivalent for the brachial and cephalic veins to TOF-MRV, with no difference in fat suppression. FBI-MRV would be useful in venous mapping and detection of thrombus.

Changes of the normal ovary during menstrual cycle in reproductive age on the diffusion-weighted image.

OBJECTIVE: The objective of this study was to investigate changes in magnetic resonance findings of the normal ovary during menstrual cycle on diffusion-weighted image (DWI). METHODS: Magnetic resonance imaging was performed in 9 healthy females at the menstrual, periovulatory, and luteal phases using a 1.5-T unit. Signal intensity (SI) of the ovary on DWI with a b value of 1000 s/mm was visually scored. The ovary-to-muscle contrast ratios on DWI and apparent diffusion coefficient (ADC) values were also evaluated. RESULTS: All the ovaries were identified, and higher SI than the nerve root was identified in 70% (38/54) of the ovaries, although visual scores did not show significant difference among menstrual phases. The mean ADC values (10 mm/s) were 1.71 (SD, 0.27), 1.71 (SD, 0.22), and 1.67 (SD, 0.19) in menstrual, periovulatory, and luteal phases, respectively. No phase-dependent change was observed in contrast ratios and ADC values. CONCLUSION: The normal ovary in fertile period shows high SI enough to be identified on DWI, and observed values are independent of the menstrual cycle.

Advanced extragonadal yolk sac tumor serially followed up with (18)F-fluorodexyglucose-positoron emission tomography and computerized tomography and serum alpha-fetoprotein.

Although yolk sac tumors (YSTs) are the second most common malignant germ cell tumor of the ovary, those arising from the omentum or pelvic peritoneum are extremely rare and have no established treatment guidelines. We report a case of a primary YST disseminated throughout the abdomen and associated with a high serum alpha-fetoprotein (AFP) elevation (441 611 ng/ml). Optimal cytoreduction was not achieved in order to preserve the patient's fertility and avoid adjacent organ injury. Residual tumor responded to adjuvant chemotherapy with a sharp decline in AFP levels, and confirmed remission was documented by serial (18)F-fluorodexyglucose-positoron emission tomography and computerized tomography (FDG-PET/CT). In cases of advanced YST with unresectable residual disease, AFP levels combined with FDG-PET/CT scans may be a helpful way to monitor treatment response and assist in treatment planning for a disease that primarily affects young women who may desire to preserve fertility.

Diffusion tensor MRI of the kidney at 3.0 and 1.5 Tesla.

BACKGROUND: Diffusion tensor imaging (DTI) at 3 T provides information on the microstructure and pathophysiology of tissues that is not available from conventional imaging with an advantage of high signal to noise ratio (SNR). PURPOSE: To evaluate the feasibility of DTI of the normal kidney at 3.0 T compared to results obtained at 1.5 T. MATERIAL AND METHODS: DTI of the normal kidney of 15 healthy volunteers obtained with 3.0 and 1.5 T scanners using respiration-triggered acquisition was examined. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of both the renal cortex and the medulla and SNRs were measured (b-values 0 and 400 s/mm², diffusion direction of 6). The image quality of FA and ADC maps was also compared subjectively. RESULTS: The FA values of the renal cortex were 0.15 ± 0.03 at 3.0 T and 0.14± 0.03 at 1.5 T on average. This difference was not significant. The FA values of the renal medulla were 0.49 ±0.04 at 3.0 T and 0.42 ± 0.05 at 1.5 T. ADC values of the renal cortex were 2.46 x 10⁻³± 0.09 mm<²/s at 3.0 T and 2.20 x 10⁻³±0.11 mm²/s at 1.5 T. The ADC values of the renal medulla were 2.08 x 10⁻³ ± 0.08 mm²/s at 3.0 T and 1.90 x 10⁻³± 0.11 mm²/s at 1.5 T. These FA and ADC values were consistent with previous publications. The difference was significant for the FA value of the medulla (P< 0.01) and ADC values in both cortex and medulla (P < 0.01). The subjective image quality of the FA map with the 3.0 T scanner was significantly superior to that with the 1.5 T scanner (P< 0.01), but not significant for the ADC map (P = 0.18). There was a significant difference in SNR between 3.0 T (48.8 ± 6.6) and 1.5 T images (32.8 ± 5.0). CONCLUSION: The feasibility of renal DTI with a 3.0 T magnet resulting in improved SNR was demonstrated.