Ultrafast sequence-based prediction model and nomogram to differentiate additional suspicious lesions on preoperative breast MRI.

OBJECTIVES: To investigate whether ultrafast sequence improves the diagnostic performance of conventional dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in differentiating additional suspicious lesions (ASLs) on preoperative breast MRI. MATERIALS AND METHODS: A retrospective database search identified 668 consecutive patients who underwent preoperative breast DCE-MRI with ultrafast sequence between June 2020 and July 2021. Among these, 107 ASLs from 98 patients with breast cancer (36 multifocal, 42 multicentric, and 29 contralateral) were identified. Clinical, pathological, conventional MRI findings, and ultrafast sequence-derived parameters were collected. A prediction model that adds ultrafast sequence-derived parameters to clinical, pathological, and conventional MRI findings was developed and validated internally. Decision curve analysis and net reclassification index statistics were performed. A nomogram was constructed. RESULTS: The ultrafast model adding time to peak enhancement, time to enhancement, and maximum slope showed a significantly increased area under the receiver operating characteristic curve compared with the conventional model which includes age, human epidermal growth factor receptor 2 expression of index cancer, size of index cancer, lesion type of index cancer, location of ASL, and size of ASL (0.92 vs. 0.82; p = 0.002). The decision curve analysis showed that the ultrafast model had a higher overall net benefit than the conventional model. The net reclassification index of ultrafast model was 23.3% (p = 0.001). CONCLUSION: A combination of ultrafast sequence-derived parameters with clinical, pathological, and conventional MRI findings can aid in the differentiation of ASL on preoperative breast MRI. CLINICAL RELEVANCE STATEMENT: Our prediction model and nomogram that was based on ultrafast sequence-derived parameters could help radiologists differentiate ASLs on preoperative breast MRI. KEY POINTS: Ultrafast MRI can diminish background parenchymal enhancement and possibly improve diagnostic accuracy for additional suspicious lesions (ASLs). Location of ASL, larger size of ASL, and higher maximum slope were associated with malignant ASL. The ultrafast model and nomogram can help preoperatively differentiate additional malignancies.

Association of Ultrasonography Features of Follicular Thyroid Carcinoma With Tumor Invasiveness and Prognosis Based on WHO Classification and TERT Promoter Mutation.

OBJECTIVE: To investigate the association of ultrasound (US) features of follicular thyroid carcinoma (FTC) with tumor invasiveness and prognosis based on the World Health Organization (WHO) classification and telomerase reverse transcriptase (TERT) promoter mutations. MATERIALS AND METHODS: This retrospective study included 54 surgically confirmed FTC patients with US images and TERT promoter mutations (41 females and 13 males; median age [interquartile range], 40 years [30-51 years]). The WHO classification consisted of minimally invasive (MI), encapsulated angioinvasive (EA), and widely invasive (WI) FTCs. Alternative classifications included Group 1 (MI-FTC and EA-FTC with wild type TERT), Group 2 (WI-FTC with wild type TERT), and Group 3 (EA-FTC and WI-FTC with mutant TERT). Each nodule was categorized according to the US patterns of the Korean Thyroid Imaging Reporting and Data System (K-TIRADS) and American College of Radiology-TIRADS (ACR-TIRADS). The Jonckheere-Terpstra and Cochran-Armitage tests were used for statistical analysis. RESULTS: Among 54 patients, 29 (53.7%) had MI-FTC, 16 (29.6%) had EA-FTC, and nine (16.7%) had WI-FTC. In both the classifications, lobulation, irregular margins, and final assessment categories showed significant differences (all Ps ≤ 0.04). Furthermore, the incidences of lobulation, irregular margin, and high suspicion category tended to increase with increasing tumor invasiveness and worse prognosis (all Ps for trend ≤ 0.006). In the WHO groups, hypoechogenicity differed significantly among the groups (P = 0.01) and tended to increase in proportion as tumor invasiveness increased (P for trend = 0.02). In the alternative group, punctate echogenic foci were associated with prognosis (P = 0.03, P for trend = 0.03). CONCLUSION: Increasing tumor invasiveness and worsening prognosis in FTC based on the WHO classification and TERT promoter mutation results were positively correlated with US features that indicate malignant probability according to both K-TIRADS and ACR-TIRADS.

The Parathyroid Gland: An Overall Review of the Hidden Organ for Radiologists.

Parathyroid glands are small endocrine glands that regulate calcium metabolism by producing parathyroid hormone (PTH). These are located at the back of the thyroid gland. Typically, four glands comprise the parathyroid glands, although their numbers may vary among individuals. Parathyroid diseases are related to parathyroid gland dysfunction and can be caused by problems with the parathyroid gland itself or abnormal serum calcium levels arising from renal disease. In recent years, as comprehensive health checkups have become more common, abnormal serum calcium levels are often found incidentally in blood tests, after which several additional tests, including a PTH test, ultrasonography (US), technetium-99m sestamibi parathyroid scan, single-photon-emission CT (SPECT)/CT, four-dimensional CT (4D-CT), and PET/CT, are performed for further evaluation. However, the parathyroid gland remains an organ less familiar to radiologists. Therefore, the normal anatomy, pathophysiology, imaging, and clinical findings of the parathyroid gland and its associated diseases are discussed here.

Role of ultrasound in predicting telomerase reverse transcriptase (TERT) promoter mutation in follicular thyroid carcinoma.

Telomerase reverse transcriptase (TERT) promoter mutations are associated with tumor aggressiveness. This study aimed to demonstrate the ultrasonographic (US) features of TERT promoter-mutated follicular thyroid cancer (FTC) and evaluate their predictive performance. A total of 63 patients with surgically confirmed FTC between August 1995 and April 2021 were included. All data were available for analysis of preoperative US findings and TERT promoter mutation results. Genomic DNA was extracted from the archived surgical specimens to identify TERT promoter mutations. Logistic regression analysis was performed to compare US findings between TERT promoter-mutated and wild-type FTCs. Of the 63 patients with FTC, 10 (15.9%) had TERT promoter mutations. TERT promoter-mutated FTCs demonstrated significantly different US suspicion categories compared to wild-type FTCs (Ps = 0.0054 for K-TIRADS and 0.0208 for ACR-TIRADS), with a trend toward an increasing prevalence of the high suspicion category (40.0% for both K-TIRADS and ACR-TIRADS; Ps for trend = 0.0030 for K-TIRADS and 0.0032 for ACR-TIRADS). Microlobulated margins and punctate echogenic foci were independent risk factors associated with TERT promoter mutation in FTC (odds ratio = 9.693, 95% confidence interval = 1.666-56.401, p = 0.0115 for margins; odds ratio = 8.033, 95% confidence interval = 1.424-45.309, p = 0.0182 for punctate echogenic foci). There were no significant differences in the composition and echogenicity of the TERT promoter-mutated and wild-type FTCs. TERT promoter-mutated FTCs were categorized more frequently as high suspicion by the K-TIRADS and ACR-TIRADS. Based on US findings, the independent risk factors for TERT promoter mutations in FTC are microlobulated margins and punctate echogenic foci.

Determination of axillary lymph node status by fine-needle aspiration: preoperative axillary staging vs. postoperative surveillance for breast cancers.

Background: Despite the common use of ultrasound (US)-guided fine-needle aspiration (FNA) for axillary node (AN) in breast cancer patients, only a limited number of studies are available regarding the diagnostic performance of AN-FNA according to the suspicion level based on US findings. This study compares the outcomes of US-guided AN-FNA in breast cancer patients, differentiating between those undergoing staging and surveillance. Methods: A cross-sectional retrospective study with retrospective analysis was conducted on 767 consecutive AN-FNA procedures performed in 2017 at Samsung Medical Center in Seoul, with 654 for staging and 113 for surveillance in breast cancer patients. The radiologists performed axillary US and the specific finding was prospectively classified into the AN-reporting and data system (AN-RADS) category 3-5 before FNA. The malignancy rate of each category was evaluated. The chi-square test, with or without Bonferroni correction, or Fisher's exact test was used to compare the malignancy rates between the staging and surveillance groups for each category. Results: Among the 767 AN-FNAs, 424 (55.3%) were malignant. The malignancy rate was significantly higher in the staging group (59.5%) than in the surveillance group (31.0%, P<0.0001). The distribution of AN-RADS categories differed between the groups (P=0.015), with 4A being the most common. The malignancy rates in categories 3, 4A, 4B, 4C, and 5 were as follows: 5.6%, 36.0%, 77.4%, 87.7%, and 98.4% in the staging group, and 0.0%, 9.7%, 53.3%, 88.9%, and 100% in the surveillance group. The malignancy rate was significantly different between the two groups only in category 4A (P=0.0001). Conclusions: AN-FNA according to AN-RADS category appears to be an appropriate method for determination of axillary nodal status. Overall malignancy rate of AN-FNA in breast cancer patients was higher in the staging group than in the surveillance group. According to the suspicion level, the difference between two groups was significant only in category 4A.

Prediction model for individualized precision surgery in breast cancer patients with complete response on MRI and residual calcifications on mammography after neoadjuvant chemotherapy.

BACKGROUND: Identifying whether there is residual carcinoma in remaining suspicious calcifications after neoadjuvant chemotherapy (NAC) in breast cancer patients can provide crucial information for surgeons in determining the most appropriate surgical approach. Therefore, we investigated factors predicting calcifications without residual carcinoma (ypCalc_0) or with residual carcinoma (ypCalc_ca) and aimed to develop a prediction model for patients exhibiting residual suspicious calcifications on mammography but complete response on MRI after NAC. METHODS: This retrospective study included breast cancer patients undergoing NAC, showing residual suspicious mammographic calcifications but complete response on MRI between January 2019 and December 2020 (development set) and between January 2021 and December 2022 (validation set). Multivariable logistic regression analysis identified significant factors associated with ypCalc_0. The prediction model, developed using a decision tree and factors from logistic regression analysis, was validated in the validation set. RESULTS: The development set included 134 women (mean age, 50.6 years; 91 with ypCalc_0 and 43 with ypCalc_ca) and validation set included 146 women (mean age, 51.0 years; 108 with ypCalc_0 and 38 with ypCalc_ca). Molecular subtype (P = .0002) and high Ki-67 (P = .02) emerged as significant independent factors associated with ypCalc_0 in the development set. The prediction model, incorporating hormone receptor (HR)-/human epidermal growth factor receptor 2 (HER2)+ with high Ki-67 as ypCalc_0 predictors, and HR+/HER2- cancers or HR+/HER2+ or triple-negative (TN) cancers with low Ki-67, as ypCalc_ca predictors, achieved an area under receiver operating characteristic curve of 0.844 (95% CI 0.774-0.914) in the validation set. CONCLUSION: Minimized surgery may be considered for managing residual calcifications in HR-/HER2+ with high Ki-67 cancers, while complete excision is recommended for HR+/HER2- breast cancers or for HR+/HER2+or TN breast cancers with low Ki-67.

Delayed Cancer Diagnosis in Thyroid Nodules Initially Treated as Benign With Radiofrequency Ablation: Ultrasound Characteristics and Predictors for Cancer.

OBJECTIVE: Regrowth after radiofrequency ablation (RFA) of symptomatic large thyroid nodules, initially treated as benign, sometimes turns out to be malignancies. This study aimed to assess the ultrasound (US) characteristics of thyroid nodules initially treated as benign with RFA and later diagnosed as cancers, predictive factors for cancers masquerading as benign, and methods to avoid RFA in these cancers. MATERIALS AND METHODS: We reviewed the medical records of 134 consecutive patients with 148 nodules who underwent RFA between February 2008 and November 2016 for the debulking of symptomatic thyroid nodules diagnosed as benign using US-guided biopsy. We investigated the pre-RFA characteristics of the thyroid nodules, changes at follow-up after RFA, and the final surgical pathology. RESULTS: Nodule regrowth after RFA was observed in 36 (24.3%) of the 148 benign nodules. Twenty-two of the 36 nodules were surgically removed, and malignancies were confirmed in seven (19.4% of 36). Of the 22 nodules removed surgically, pre-RFA median volume (range) was significantly larger for malignant nodules than for benign nodules: 22.4 (13.9-84.5) vs. 13.4 (7.3-16.8) mL (P = 0.04). There was no significant difference in the regrowth interval between benign and malignant nodules (P = 0.49). The median volume reduction rate (range) at 12 months was significantly lower for malignant nodules than for benign nodules (51.4% [0-57.8] vs. 83.8% [47.9-89.6]) (P = 0.01). The pre-RFA benignity of all seven malignant nodules was confirmed using two US-guided fine-needle aspirations (FNAs), except for one nodule, which was confirmed using US-guided core-needle biopsy (CNB). Regrown malignant nodules were diagnosed as suspicious follicular neoplasms by CNB. Histological examination of the malignant nodules revealed follicular thyroid carcinomas, except for one follicular variant, a papillary thyroid carcinoma. CONCLUSION: Symptomatic large benign thyroid nodules showing regrowth or suboptimal reduction after RFA may have malignant potential. The confirmation of these nodules is better with CNB than with FNA.

Subcategorization of intermediate suspicion thyroid nodules based on suspicious ultrasonographic findings.

PURPOSE: This study compared the malignancy risk of intermediate suspicion thyroid nodules according to the presence of suspicious ultrasonographic (US) findings. METHODS: From January 2014 to December 2014, 299 consecutive intermediate suspicion thyroid nodules in 281 patients (mean age, 50.6±12.5 years) with final diagnoses were included in this study. Two radiologists retrospectively reviewed the US findings and subcategorized the intermediate suspicion category into nodules without suspicious findings and nodules with suspicious findings, including punctate echogenic foci, nonparallel orientation, or irregular margins. The malignancy rates were compared between the two subcategory groups. RESULTS: Of the 299 intermediate suspicion thyroid nodules, 230 (76.9%) were subcategorized as nodules without suspicious findings and 69 (23.1%) as nodules with suspicious findings. The total malignancy rate was 33.4% (100/299) and the malignancy rate of nodules with suspicious findings was significantly higher than that of nodules without suspicious findings (47.8% vs. 29.1%, P=0.004). In nodules with suspicious findings, the most common suspicious finding was punctate echogenic foci (48/82, 58.5%) followed by nonparallel orientation (22/82, 26.8%) and irregular margins (12/82, 14.6%). Thirteen nodules had two suspicious findings simultaneously. A linearly increasing trend in the malignancy rate was observed according to the number of suspicious US findings (P for trend=0.001). CONCLUSION: Intermediate suspicion thyroid nodules with suspicious findings showed a higher malignancy rate than those without suspicious findings. Further management guidelines for nodules with suspicious findings should differ from guidelines for nodules without suspicious findings, even in the same US category.

Characteristics of Breast Charcoal Granuloma: A Delayed Complication Following Tattoo Localization.

Rationale and Objective: To evaluate the characteristic clinical and imaging findings of charcoal granuloma and suggest features that may differentiate charcoal granuloma from breast cancer. Materials and Methods: This retrospective study included 18 patients with a histologically confirmed breast charcoal granuloma between 2005 and 2021 at a single institution. All patients had a history of breast surgery after ultrasound (US)-guided charcoal marking. Two radiologists analyzed the radiologic findings of charcoal granulomas, including the presence of a mass or calcification; the shape, margin and density of the masses on mammography; and the location, size, shape, margin, orientation, echogenicity, vascularity, presence of an echogenic halo, and posterior acoustic shadowing on US. In cases with available follow-up images, we also investigated whether the size and shape had changed. Results: The median interval between breast surgery and the diagnosis of charcoal granuloma was 2.3 years (range, 0.7-18.3 years). Thirteen lesions (72.2%) were detected on screening images. In 11 (61.1%) cases, the surgical incision was not made in the tattooed skin area. Mammography showed positive findings in 10/15 patients, and most lesions were isodense masses (70%). There were no cases with calcification. On US, all lesions were masses and showed a taller-than-wide orientation (61.1%), round or oval shape (55.6%), and iso- or hyperechogenicity (83.3%). Echogenic halo (27.8%) and posterior acoustic shadowing (16.7%) were uncommon. On Doppler US, only four cases (22.2%) showed increased vascularity. Most were classified as BI-RADS 3 (38.9%) or 4A (50.0%). After biopsy, 12 patients had follow-up mammography and US. The size of the lesion decreased in nine cases and remained unchanged in three cases. A decrease in the lesion size after biopsy showed a negative correlation with the interval between detection on imaging and biopsy (p = 0.04). Conclusion: Charcoal granuloma is most commonly found 2-3 years after surgery and occurs more frequently when the incision site is different from the tattooed skin area. US findings of tall and round or oval masses with iso- or hyperechogenicity without increased vascularity could help to differentiate them from malignancies.

Correction: Kim et al. Assessment of Enhancement Kinetics Improves the Specificity of Abbreviated Breast MRI: Performance in an Enriched Cohort. Diagnostics 2023, 13, 136.

There were errors in the original publication [...].

Analysis of Prognoses according to Breast MRI Results in Patients with Axillary Lymph Node Metastases from an Unknown Primary Origin.

PURPOSE: To compare the prognosis of patients with axillary adenocarcinoma from an unknown primary (ACUPax) origin with negative MRI results and those with MRI-detected primary breast cancers. MATERIALS AND METHODS: The breast MRI images of 32 patients with ACUPax without signs of primary breast cancer on mammography and ultrasound (US) were analyzed. Spot compression-magnification mammography and second-look US were performed for the area of MRI abnormality in patients with positive results; any positive findings corresponding to the MRI abnormality were confirmed by biopsy. If suspicious MRI lesions could not be localized on mammography or US, MR-guided biopsy or excision biopsy after MR-guided localization was performed. We compared the prognosis of patients with negative breast MRI with that for patients with MRI-detected primary breast cancers. RESULTS: Primary breast cancers were confirmed in 8 (25%) patients after breast MRI. Primary breast cancers were not detected on MRI in 24 (75%) patients, including five cases of false-positive MRI results. Twenty-three patients underwent axillary lymph node dissection (ALND) followed by whole breast radiation therapy (WBRT) and chemotherapy (n=17) or subsequent chemotherapy only (n=2). Recurrence or distant metastasis did not occur during follow up in 7/8 patients with MRI-detected primary breast cancers and 22/24 patients with negative MRI results. Regional recurrence or distant metastasis did not occur in any MR-negative patient who received adjuvant chemotherapy after ALND and WBRT. CONCLUSION: The prognoses of MR-negative patients with ACUPax who received ALND and WBRT followed by chemotherapy were as good as those of patients with MRI-detected primary breast cancers.

Clinical Outcome of Ultrasound-Detected Perforated Necrotizing Enterocolitis without Radiographic Pneumoperitoneum in Very Preterm Infants.

OBJECTIVES: To investigate the clinical outcomes of ultrasound (US)-detected perforated necrotizing enterocolitis (NEC) without radiographic pneumoperitoneum in very preterm infants. METHODS: In this single-center retrospective study, very preterm infants who underwent a laparotomy for perforated NEC during their neonatal intensive care unit stay were classified into two groups according to the absence or presence of pneumoperitoneum on radiographs (the case versus the control groups). The primary outcome was death before discharge, and the secondary outcomes included major morbidities and body weight at 36 weeks postmenstrual age (PMA). RESULTS: Of the 57 infants with perforated NEC, 12 (21%) had no pneumoperitoneum on the radiographs and were diagnosed with perforated NEC on the US. In the multivariable analyses, the primary outcome of death before discharge was significantly lower in infants with perforated NEC without radiographic pneumoperitoneum than in those with perforated NEC and radiographic pneumoperitoneum (8% [1/12] vs. 44% [20/45]; adjusted odds ratio [OR], 0.02; 95% confidence interval [CI], 0.00-0.61; p = 0.025). The secondary outcomes (short bowel syndrome, total parenteral nutrition dependence for 3 months or more, the length of their hospital stay, a bowel stricture requiring surgery, sepsis after the laparotomy, acute kidney injury after the laparotomy, and body weight at 36 weeks PMA) did not differ significantly between the two groups. CONCLUSIONS: Very preterm infants with US-detected perforated NEC without radiographic pneumoperitoneum had a lower risk of death before discharge than those with perforated NEC and radiographic pneumoperitoneum. Bowel USs may have a potential role in surgical decision-making in infants with advanced NEC.

Clinical significance of a 10-mm cutoff size for adrenal lesions: a retrospective study with 547 non-oncologic patients undergoing adrenal computed tomography.

PURPOSE: To investigate the proportion of clinically significant adrenal lesions in patients with a subcentimeter adrenal lesion, and the sensitivity of a cutoff size of 10 mm on computed tomography (CT). METHODS: This retrospective study included consecutive 547 non-oncologic patients who underwent adrenal CT. Clinically significant adrenal lesions were defined as those that were biochemically abnormal (n = 99) or surgically resected according to the clinician's decision (n = 23). Long-axis diameters (LDs) and short-axis diameters (SDs) of the lesions were measured on CT by two independent readers. Likelihood of the focal lesion was analyzed using a five-point scale (1 = very low; 5 = very high). 66 Sensitivities for clinically significant lesions were analyzed according to cutoff size. Proportions of the clinically significant lesions for subcentimeter lesions were analyzed according to the visual score. RESULTS: Sensitivities for clinically significant lesions for cutoffs of 10, 15, and 20 mm were 93%, 79%, and 63% for LD and 85%, 61%, and 49% for SD for Reader 1 and 89%, 78%, and 65% for LD and 80%, 65%, and 48% for SD for Reader 2, respectively (p < 0.001 for 10 mm versus the other cutoffs). In subcentimeter lesions with visual scores of 1-3, the proportions of clinically significant lesions were 5.4% for LD or SD for Reader 1 and 6.6% for LD and 7.7% for SD for Reader 2, respectively. CONCLUSION: A lesion LD of ≥ 10 mm was a reasonable cutoff for determining adrenal abnormality. Subcentimeter lesions without visually high suspicion had a low risk of clinical significant lesions in our study cohort. Higher cutoffs significantly decreased sensitivity.

A Primary Neuroendocrine Tumor Mimicking a Thrombus in the Left Atrial Appendage.

Most cardiac tumors are metastases, and primary cardiac tumors are rare; even among primary cardiac tumors, primary cardiac neuroendocrine tumors (NETs) are extremely rare. Herein, we report a case of a patient presenting a left atrial mass without past medical history. Because of the location and movement of the mass, as well as the patient's cerebral infarction episode, the mass was initially suspected to be a thrombus. However, the mass was surgically diagnosed as NET.

Assessment of Enhancement Kinetics Improves the Specificity of Abbreviated Breast MRI: Performance in an Enriched Cohort.

Objective: To investigate the added value of kinetic information for breast lesion evaluation on abbreviated breast MRI (AB-MRI). Methods: This retrospective study analyzed 207 breast lesions with Breast Imaging Reporting and Data System categories 3, 4, or 5 on AB-MRI in 198 consecutive patients who had breast MRI for screening after breast cancer surgery between January 2017 and December 2019. All lesions were pathologically confirmed or stable on follow-up images for 2 years or more. Kinetic information of the lesions regarding the degree and rate of enhancement on the first post-contrast-enhanced image and the enhancement curve type from two post-contrast-enhanced images were analyzed on a commercially available computer-assisted diagnosis system. The diagnostic performances of AB-MRI with morphological analysis alone and with the addition of kinetic information were compared using the McNemar test. Results: Of 207 lesions, 59 (28.5%) were malignant and 148 (71.5%) were benign. The addition of an enhancement degree of ≥90% to the morphological analysis significantly increased the specificity of AB-MRI (29.7% vs. 52.7%, p < 0.001) without significantly reducing the sensitivity (94.9% vs. 89.8%, p = 0.083) compared to morphological analysis alone. Unnecessary biopsy could have been avoided in 34 benign lesions, although three malignant lesions could have been missed. For detecting invasive cancer, adding an enhancement degree ≥107% to the morphological analysis significantly increased the specificity (26.5% vs. 57.6%, p < 0.001) without significantly decreasing the sensitivity (94.6% vs. 86.5%, p = 0.083). Conclusion: Adding the degree of enhancement on the first post-contrast-enhanced image to the morphological analysis resulted in higher AB-MRI specificity without compromising its sensitivity.

Three-Dimensional Printed Model of Partial Anomalous Pulmonary Venous Return with Biatrial Connection.

Partial anomalous pulmonary venous return (PAPVR) is a rare congenital cardiac anomaly that can be difficult to detect and often remains undiagnosed. PAPVR is diagnosed using non-invasive imaging techniques such as echocardiography, CT, and MRI. Image data are reviewed on a 2-dimensional (D) monitor, which may not facilitate a good understanding of the complex 3D heart structure. In recent years, 3D printing technology, which allows the creation of physical cardiac models using source image datasets obtained from cardiac CT or MRI, has been increasingly used in the medical field. We report a case involving a 3D-printed model of PAPVR with a biatrial connection. This model demonstrated separate drainages of the right upper and middle pulmonary veins into the lower superior vena cava (SVC) and the junction between the SVC and the right atrium, respectively, with biatrial communication through the right middle pulmonary vein.