Perinephric myxoid pseudotumor of fat: a multimodality imaging case series.

Perinephric myxoid pseudotumor of fat (PMPF) is an unusual clinical entity with few prior imaging case reports. We report a multimodality imaging case series of PMPF, consisting of four cases seen in our department with both imaging studies and histopathologic confirmation. Three of the four patients had a history of advanced non-neoplastic renal disease. The perirenal masses in these cases varied in size and appearance. Some lesions resembled cysts or contained macroscopic fat. Enhancement was equivocal on CT, but prominent in one case on MRI and in another on contrast-enhanced ultrasound. Although not known to be malignant, PMPF may be confused for a cyst, liposarcoma, or hypovascular solid neoplasm on imaging. The dominant mass was resected in two cases because of concern for malignancy, while percutaneous CT-guided biopsy was performed in the other two. Mouse double minute 2 (MDM2) gene amplification by fluorescence in situ hybridization (FISH) was negative in all four cases, excluding well-differentiated liposarcoma. Radiologists should be familiar with PMPF to provide appropriate guidance on clinical management.

PD-1 inhibition therapy for advanced cutaneous squamous cell carcinoma: a retrospective analysis from the University of Southern California.

PURPOSE: Approximately 5% of patients with cutaneous squamous cell carcinoma (CSCC) may develop recurrent or metastatic disease. The management of such cases is challenging and requires multi-disciplinary care. Immunotherapy using PD-1 inhibition was approved to treat unresectable or metastatic CSCC in 2018. Given limited data regarding clinical outcomes outside of published trials, we describe our experience using this therapy. METHODS: We retrospectively reviewed all patients treated with PD-1 inhibition as therapy for locally advanced, regionally metastatic or distant metastatic CSCC at the University of Southern California. Clinicopathological characteristics, treatment data using PD-1 inhibitors, and outcomes were assessed. RESULTS: Among 26 patients treated with PD-1 inhibition, the objective response rate was 42.3%, with 19.2% of patients having partial response and 23.1% having complete response to therapy. The median progression-free survival was 5.4 months. Median tumor mutational burden (TMB) was higher among responders compared to non-responders (60 vs. 9 Mut/Mb, p = 0.04). Primary CSCC tumor location on the head/neck was also associated with response to PD-1 inhibition (p = 0.04). Two patients with mutations affecting mismatch repair deficiency were noted to have complete response to treatment. No other variables were associated with treatment outcomes. CONCLUSION: PD-1 inhibition produces durable responses among patients with advanced or metastatic CSCC. PD-1 inhibition therapy is well tolerated, but patients should be monitored closely for immune-related adverse events, particularly frail or immune-suppressed patients. Further investigation of potential biomarkers to help identify patients who will derive the most benefit from this therapeutic option is needed.

Use of Contrast Ultrasound for Renal Mass Evaluation.

An introduction to the expanding modality of contrast-enhanced ultrasound is provided, along with basics on contrast agents and technique. The contrast ultrasound findings of multiple renal tumors are reviewed with examples, including clear cell renal cell carcinoma, papillary renal cell carcinoma, chromophobe renal cell carcinoma, other rare renal cell carcinoma subtypes, oncocytoma, upper tract urothelial carcinoma, lymphoma, and angiomyolipoma, followed also by brief discussions of renal infections and pseudolesions.

Contrast-Enhanced Ultrasound With Perflubutane for Sentinel Lymph Node Mapping in Cutaneous Melanoma: A Pilot Study.

OBJECTIVE: To study the feasibility of contrast-enhanced ultrasound (CEUS) for identification of SLN associated with cutaneous melanoma. STUDY DESIGN: Single arm pilot study in a swine animal model. METHODS: One milliliter of perflubutane (Sonazoid, GE Healthcare, Milwaukee, WI) was injected into the peritumoral dermis in five swine with cutaneous melanoma. Ultrasonography was used to follow enhancing lymphatic channels to lymph nodes (LN). Intradermal injection of vital blue (VB) dye was used as a positive control. LN identified by either method were excised and examined histologically. RESULTS: There were five primary cutaneous melanomas with mean area of 4.36 ± 4.75 cm2 and Breslow depth of 3.6 ± 1.5 mm. Six possible sentinel lymph node (SLN)s were identified with CEUS, and nine were identified with VB. SLN averaged 12.44 ± 6.15 cm from the primary tumor. Four of six (67%) SLNs identified by CEUS and four of nine (44%) candidate SLNs identified by VB contained histologically confirmed metastatic melanoma. All six CEUS-identified SLNs were also identified with VB. Two LNs not containing melanoma were identified by CEUS; three were identified with VB. In all SLN with metastases, metastatic cells were scattered throughout the LN and not clustered in a discrete mass. CONCLUSION: CEUS with perflubutane feasibly identifies SLN associated with cutaneous melanoma and may be a useful adjunct technology in facilitating precise SLN dissection. Our work supports a clinical trial investigating the use of CEUS for this application. LEVEL OF EVIDENCE: NA Laryngoscope, 129:1117-1122, 2019.

Quantitative assessment of solid renal masses by contrast-enhanced ultrasound with time-intensity curves: how we do it.

PURPOSE: To discuss the evaluation of the enhancement curve over time of the major renal cell carcinoma (RCC) subtypes, oncocytoma, and lipid-poor angiomyolipoma, to aid in the preoperative differentiation of these entities. Differentiation of these lesions is important, given the different prognoses of the subtypes, as well as the desire to avoid resecting benign lesions. METHODS: We discuss findings from CT, MR, and US, but with a special emphasis on contrast-enhanced ultrasound (CEUS). CEUS technique is described, as well as time-intensity curve analysis. RESULTS: Examples of each of the major RCC subtypes (clear cell, papillary, and chromophobe) are shown, as well as examples of oncocytoma and lipid-poor angiomyolipoma. For each lesion, the time-intensity curve of enhancement on CEUS is reviewed, and correlated with the enhancement curve over time reported for multiphase CT and MR. CONCLUSIONS: Preoperative differentiation of the most common solid renal masses is important, and the time-intensity curves of these lesions show some distinguishing features that can aid in this differentiation. The use of CEUS is increasing, and as a modality it is especially well suited to the evaluation of the time-intensity curve.

Characteristics of Detected and Missed Prostate Cancer Foci on 3-T Multiparametric MRI Using an Endorectal Coil Correlated With Whole-Mount Thin-Section Histopathology.

OBJECTIVE: The objective of this study was to determine the characteristics of prostate cancer foci missed on 3-T multiparametric MRI performed with an endorectal coil. MATERIALS AND METHODS: The MRI examinations of 122 patients who underwent 3-T multiparametric MRI of the prostate with an endorectal coil were compared with whole-mount histopathology obtained after radical prostatectomy. The mean age of the patients was 60.6 years (SD, 7.6 years), and the mean prostate-specific antigen value was 7.2 ng/mL (SD, 5.9 ng/mL). The clinical, multiparametric MRI (i.e., T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging), and histopathologic features were obtained. After an independent review, two blinded genitourinary radiologists matched each case with a genitourinary pathologist. A structured reporting system was used to classify the multiparametric MRI features of each MRI-detected lesion. A chi-square analysis was performed for categoric variables, and the t test was performed for continuous variables. RESULTS: On whole-mount histopathology, 285 prostate cancer foci were detected in 122 patients. Of the 285 cancer foci detected at histopathology, 153 (53.3%) were missed on MRI and 132 (46.7%) were detected on MRI. Of the missed lesions, 75.2% were low-grade prostate cancer. Multiparametric MRI had a significantly higher sensitivity for prostate cancer foci 1 cm or larger than for subcentimeter foci (81.1% vs 18.9%, respectively; p < 0.001), for lesions with a Gleason score of 7 or greater than for lesions with a Gleason score of 6 (72.7% vs 27.3%; p < 0.01), and for index lesions than for satellite lesions (80.3% vs 20.8%; p < 0.01). The 3-T multiparametric MRI examinations showed a higher detection rate for lesions in the midgland or base of the gland compared with lesions in the apex (52.3% vs 22.0%, respectively; p < 0.01). CONCLUSION: Compared with the prostate cancer lesions that were detected on multiparametric MRI, the prostate cancer lesions that were missed were significantly smaller, were more likely to be low-grade lesions (i.e., Gleason score of 6), were more commonly satellite lesions, and were more likely to be located in the prostatic apex.

Contrast-enhanced ultrasound (CEUS) of cystic and solid renal lesions: a review.

Incidentally detected renal lesions have traditionally undergone imaging characterization by contrast-enhanced computer tomography (CECT) or magnetic resonance imaging. Contrast-enhanced ultrasound (CEUS) of renal lesions is a relatively novel, but increasingly utilized, diagnostic modality. CEUS has advantages over CECT and MRI including unmatched temporal resolution due to continuous real-time imaging, lack of nephrotoxicity, and potential cost savings. CEUS has been most thoroughly evaluated in workup of complex cystic renal lesions, where it has been proposed as a replacement for CECT. Using CEUS to differentiate benign from malignant solid renal lesions has also been studied, but has proven difficult due to overlapping imaging features. Monitoring minimally invasive treatments of renal masses is an emerging application of CEUS. An additional promising area is quantitative analysis of renal masses using CEUS. This review discusses the scientific literature on renal CEUS, with an emphasis on imaging features differentiating various cystic and solid renal lesions.

Cancers of the oral cavity and oropharynx: FDG PET with contrast-enhanced CT in the posttreatment setting.

The combined use of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and contrast material-enhanced computed tomography (CT) for posttreatment monitoring of cancers of the oral cavity and oropharynx has steadily increased in recent years. FDG PET/CT offers many advantages for evaluating the effects of therapy, determining whether residual or recurrent disease is present, and assessing the extent of nodal disease. Because of the high negative predictive value of this imaging test, some have advocated the deferral of neck dissection in patients with negative findings at FDG PET/CT after chemotherapy and radiation therapy; positive findings may have a similarly heavy influence on the future course of treatment. Thus, the accuracy of image interpretation is crucial. However, the interpretation of posttreatment FDG PET images is challenging, with multiple potential pitfalls and limitations that could lead to an incorrect analysis. Accuracy depends on a detailed knowledge of the patient's treatment history and a thorough understanding of the kinds of changes that might result from treatment. Awareness of the principles underlying the selection of the optimal interval between the completion of treatment and the first follow-up FDG PET/CT examination is especially important, since an interval that is too short could lead to false-positive or false-negative findings. A period of 12 weeks or more is generally recommended, but the optimal waiting period depends on the extent of therapy and other factors. If recurrence or progression is suspected during the waiting period, contrast-enhanced CT or magnetic resonance imaging should be performed without FDG PET.

Anteroposterior hippocampal metabolic heterogeneity: three-dimensional multivoxel proton 1H MR spectroscopic imaging--initial findings.

PURPOSE: To quantify proton magnetic resonance (MR) spectroscopy-detectable metabolite concentrations along anteroposterior axis of hippocampus in healthy young and elderly subjects. MATERIALS AND METHODS: Young (three women, three men; age range, 25-35 years) and elderly (four women, two men; age range, 68-72 years) groups underwent MR imaging and proton MR spectroscopic imaging at 3 T in this HIPAA-compliant prospective study and gave institutional review board-approved written consent. Volume of interest was centered on and tilted parallel to hippocampal anteroposterior plane. Absolute N-acetylaspartate (NAA), choline, and creatine levels were obtained in each voxel, with phantom replacement. RESULTS: Mean NAA, creatine, and choline concentrations in the young group were higher in posterior hippocampus (12.9 mmol/L +/- 2.0 [standard deviation], 7.8 mmol/L +/- 1.2, 2.3 mmol/L +/- 0.4, respectively) than anterior hippocampus (8.0 mmol/L +/- 1.1, 6.0 mmol/L +/- 1.4, 1.5 mmol/L +/- 0.2; P = .005, .02, and .0002, respectively). In the elderly group, mean concentrations were higher in posterior hippocampus (8.6 mmol/L +/- 0.9, 5.6 mmol/L +/- 0.6, 1.5 mmol/L +/- 0.2, respectively) than anterior hippocampus (7.2 mmol/L +/- 1.0, 2.4 mmol/L +/- 0.3, 1.0 mmol/L +/- 0.2; P = .006, .0001, .04, respectively). Mean concentrations were significantly higher in the young group (13.2 mmol/L +/- 1.0, 7.4 mmol/L +/- 0.8, 2.1 mmol/L +/- 0.3, respectively) than in the elderly group (9.0 mmol/L +/- 1.0, 5.8 mmol/L +/- 0.8, 1.8 mmol/L +/- 0.3; P = .0001, .01, .05, respectively). Posteroanterior metabolic gradients differed: NAA decreased faster in the young group (-1.0 mmol/L x cm(-1)) than the elderly group (-0.7 mmol/L x cm(-1)); creatine and choline concentrations decreased faster in the elderly group (-0.8 and -0.058 mmol/L x cm(-1), respectively) than the young group (-0.16 and -0.008 mmol/L x cm(-1), respectively). No left-right metabolic differences were found. CONCLUSION: Significant metabolic heterogeneity was observed between groups and along anteroposterior axis of healthy hippocampus in both groups. Age matching and consistent voxel placement are important for correct comparisons of both absolute metabolic levels and metabolite ratios in longitudinal intra- and intersubject cross-sectional studies.

Memantine decreases hippocampal glutamate levels: a magnetic resonance spectroscopy study.

Glutamate (Glu) is associated with excitotoxic cell damage. Memantine modulates the glutamate induced excitotoxicity in Alzheimer's disease (AD). No information is available as to the influence of memantine on in vivo brain glutamate levels. Hippocampal Glu levels were measured in cognitively impaired and normal individuals (n=10) before and after 6 months of memantine treatment, using three dimensional high spatial resolution (0.5 cm(3) voxels) proton magnetic resonance spectroscopy at 3 T. These measurements were also repeated in a non-treated cognitively normal group (n=6). Treatment with memantine decreased Glu/Cr (creatine) ratio in the left hippocampal region. Memantine reduced hippocampal glutamate levels, which may be consistent with its anti-excitotoxic property.